Floral Biology 2.0

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Plant Development and Morphogenesis".

Deadline for manuscript submissions: closed (31 August 2023) | Viewed by 46843

Special Issue Editor


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Guest Editor
Department of Pharmacognosy, Faculty of Pharmacy, University of Pécs, Rókus utca 2, H-7624 Pécs, Hungary
Interests: floral and pollination biology of medicinal plants and fruit trees; chemical composition of floral nectar and honey; bioactivity of honey
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Special Issue Information

Dear Colleagues,

Floral biology covers a wide array of topics, including the morphology and anatomy of floral parts, pollination by different pollen vectors, the floral rewards pollen and nectar, as well as the reproductive strategies of a plant species.

This field raises important issues such as the close relationship between flower structure and function, the adaptation of plants to pollinators with their floral traits, the background and consequences of floral polymorphisms, including the issue of incompatibility, as well as the balance between fitness and resource allocation. In addition, floral biology has numerous practical implications: flower traits affect the fruit yield and quality, which is essential in horticulture and crop production; the survival of bee colonies and honey production are determined by the quantity and quality of floral nectar and pollen; flowers can be important sources of medicinally significant chemical substances; floriculture requires breeding new varieties, and there is a growing interest in edible flowers, which in turn raises safety issues.

The study of floral biology requires a multidisciplinary approach, involving anatomy, biochemistry, botany, ethology, entomology, molecular biology, and analytical chemistry. In accordance, this Special Issue will cover a wide variety of areas connected to any aspect of floral biology, aiming to contribute to our overall knowledge of plant diversity and the importance of adaptation to changing circumstances.

In this Special Issue, original research papers, reviews, methodological papers, and perspectives focusing on various aspects of floral biology are most welcome.

Dr. Agnes Farkas
Guest Editor

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Keywords

  • bee
  • incompatibility
  • insect, nectar
  • nectary
  • pollen
  • pollination
  • reproductive
  • resource
  • reward

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Published Papers (27 papers)

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Research

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15 pages, 1864 KiB  
Article
Effect of Crown Layers on Reproductive Effort and Success in Andromonoecious Aesculus indica (Wall. ex Camb.) Hook (Sapindaceae) in a Temperate Forest of Garhwal Himalaya
by Priya Pradhan, Arun Sukumaran, Vinod Prasad Khanduri, Bhupendra Singh, Deepa Rawat, Manoj Kumar Riyal, Munesh Kumar and Marina M. S. Cabral Pinto
Plants 2024, 13(2), 183; https://doi.org/10.3390/plants13020183 - 10 Jan 2024
Viewed by 589
Abstract
The andromonoecy is an unusual sex expression in trees in which an individual plant bears both functionally staminate and hermaphrodite flowers on the inflorescences. This study aims to investigate the effect of crown layers on the floral biology and reproductive effort of Aesculus [...] Read more.
The andromonoecy is an unusual sex expression in trees in which an individual plant bears both functionally staminate and hermaphrodite flowers on the inflorescences. This study aims to investigate the effect of crown layers on the floral biology and reproductive effort of Aesculus indica (Wall. ex Camb.) Hook. The results revealed that the peak period of anthesis was between 06:00 and 08:00 h of the day. Male flower production was predominantly higher as compared to the perfect flowers on the inflorescences. There was no significant variation between total pollen production in staminate and perfect flowers. Features like protogyny and inter-level asynchrony promote xenogamy; however, intra-level asynchrony results in geitonogamy. Controlled pollination treatments revealed the existence of self-incompatibility in flowers. Pollination syndromes in flowers support ambophily. A trend of consistent improvement in reproductive success from lower canopy layers to upper crown layers in the analyzed trees was recorded. The crown layers have a significant impact on flower production, fruit, and seed set. An increase in male flower production due to the increment in the crown is a mechanism of reproductive assurance as a pollen donor and pollinator recipient and also due to the differential cost of expenditure of reproduction in crown layers. Andromonoecy in A. indica promotes self-incompatibility, and there was a tapering trend of reproductive success in the crown layers. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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18 pages, 9154 KiB  
Article
The Exploration of Flowering Mechanisms in Cherry Plants
by Yanxia Xu, Jingjing Li, Pengyi Wang, Wenhui Wang, Yuning Guo, Xueying Hao, Liyan Du and Chunling Zhou
Plants 2023, 12(23), 3980; https://doi.org/10.3390/plants12233980 - 27 Nov 2023
Viewed by 740
Abstract
Flowering cherry (Cerasus sp.) are significant spring-blooming trees. However, the short blooming period and the rarity of early and late-flowering varieties limit their use in gardens in northern China. The experiment incorporated annually early-flowering species such as Cerasus discoidea, Cerasus pseudocerasus [...] Read more.
Flowering cherry (Cerasus sp.) are significant spring-blooming trees. However, the short blooming period and the rarity of early and late-flowering varieties limit their use in gardens in northern China. The experiment incorporated annually early-flowering species such as Cerasus discoidea, Cerasus pseudocerasus ‘Introtsa’, Cerasus dielsiana, Cerasus campanulata ‘Youkou’, Cerasus yedoensis ‘Somei-Yoshino’, and Cerasus spachiana f. ascendens, as well as twice-a-year flowering species like Cerasus subhirtella ‘Autumnalis’ and Cerasus subhirtella ‘Accolade’. We observed the timing of natural events and growth measurements for specific plants over a span of two years. This research involved a thorough examination of their ability to withstand cold temperatures, considering their physiological aspects. We examined the levels of nutrients and hormones in the flower buds at various stages of development in plants that bloom yearly and every two years. The findings indicated that C. subhirtella ‘Autumnalis’ is adaptable, offering the lengthiest autumn blooming phase lasting 54 days. The hierarchy of cold tolerance was as follows: C. pseudocerasus ‘Introtsa’ > C. discoidea > Cerasus × subhirtella ‘Autumnalis’ > C. dielsiana > C. ‘Youkou’. Furthermore, the soluble protein content in leaves increased before autumn flower buds’ sprout of twice-a-year flowering varieties but declined in C. yedoensis ‘Somei-Yoshino’ within the same time. We determined that changes in nutrient content significantly contribute to the autumn opening of C. subhirtella ‘Autumnalis’ robust short branch flower buds. During the final phase of flower bud development, the rise in trans-Zeatin-riboside (ZR) and indolacetic acid (IAA) promotes the initiation of the first flowering period in C. subhirtella ‘Autumnalis’ prior to its mandatory hibernation. The occurrence of secondary flowering involves a multifaceted regulatory process. These findings serve as valuable references for delving deeper into the mechanisms governing cherry blossom formation and secondary flowering. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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15 pages, 3994 KiB  
Article
Quantification and Qualification of Floral Patterns of Coffea arabica L. in Colombia
by Carlos Andres Unigarro, Luis Carlos Imbachi, Aquiles Enrique Darghan and Claudia Patricia Flórez-Ramos
Plants 2023, 12(18), 3332; https://doi.org/10.3390/plants12183332 - 21 Sep 2023
Viewed by 1007
Abstract
The phenological patterns of coffee flowering in Colombia have typically been studied in a descriptive way, with knowledge from an inferential perspective being scarce. The present study evaluated the effect of geographic location and accession on the floral patterns and phenological descriptors of [...] Read more.
The phenological patterns of coffee flowering in Colombia have typically been studied in a descriptive way, with knowledge from an inferential perspective being scarce. The present study evaluated the effect of geographic location and accession on the floral patterns and phenological descriptors of Coffea arabica L. Fifteen accessions from the Colombian coffee collection (four tall and eleven short) were planted in the departments of Cesar, Caldas, Quindío and Cauca (Colombia). The number of flower buds per branch per plant per evaluated accession was recorded weekly during four flowering semesters. Subsequently, the phenological flowering descriptors, namely synchrony among individuals, intraindividual temporal variability and number of events were calculated. The data were analyzed descriptively, and then the inferential component was conducted using analysis of variance for a two-factor additive model and randomization restriction. The results showed that there are two flowering patterns according to the expression of flowering in the floral cycles, the “annual” class in the department of Cesar and the “continual” class in the departments of Caldas, Quindío and Cauca. The phenological descriptors show differences between the departments according to the coffee zone to which it belongs (northern, central or southern). In turn, the floral pattern of each area can be linked to the latitudinal change in daily sunshine, as well as to the distribution of rainfall and temperature, in a very broad sense and based on the literature. The data did not provide statistical evidence to suggest differences among the accessions or between the tree sizes evaluated. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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20 pages, 6402 KiB  
Article
Floral Development on Vitis vinifera Is Associated with MADS-Box Transcription Factors through the Transcriptional Regulation of VviZIP3
by Germán Saavedra Núñez, Enrique González-Villanueva and Patricio Ramos
Plants 2023, 12(18), 3322; https://doi.org/10.3390/plants12183322 - 20 Sep 2023
Viewed by 806
Abstract
Several grapevine (Vitis vinifera L.) cultivars show a tendency to develop parthenocarpic seedless grapes, affecting fruit yield and quality. This reproductive disorder originates in defective ovule fertilization due to a failure in pollen tube growth. Zinc (Zn) is a crucial trace element, [...] Read more.
Several grapevine (Vitis vinifera L.) cultivars show a tendency to develop parthenocarpic seedless grapes, affecting fruit yield and quality. This reproductive disorder originates in defective ovule fertilization due to a failure in pollen tube growth. Zinc (Zn) is a crucial trace element, playing a vital role in various physiological and metabolic processes. It is particularly essential for the healthy growth of flowers and fruits. Insufficient zinc has been suggested as a potential reason for issues in this development process. This microelement is taken up through a mechanism that involves transporters, including the ZRT-IRT-like protein (ZIP) gene family, associated with the influx of Zn into the cell. In grapevines, 20 genes for ZIP-type transporters have been described. In this study, we analyzed the expression pattern of VviZIP3 during flower development and employ transgenic methods to assess its transcriptional regulation. Furthermore, through computational examination of the promoter region, we identified two CArG boxes, recognized as responsive elements to MADS transcription factors. These factors play a key role in shaping various components of a flower, such as pollen. Our investigation of the VviZIP3 promoter confirms the functionality of these CArG boxes. Overall, our results suggest that the increased expression of VviZIP3 during flowering is likely under the influence of MADS transcription factors. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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14 pages, 1653 KiB  
Article
Callus Derived from Petals of the Rosa hybrida Breeding Line 15R-12-2 as New Material Useful for Fragrance Production
by Ka Youn Lee, Ju Young Shin, Myung Suk Ahn, Se Jin Kim, Hye Ryun An, Yae Jin Kim, O Hyeon Kwon and Su Young Lee
Plants 2023, 12(16), 2986; https://doi.org/10.3390/plants12162986 - 18 Aug 2023
Cited by 1 | Viewed by 1400
Abstract
Rose (Rosa hybrida) is a major flower crop worldwide and has long been loved for its variety of colors and scents. Roses are mainly used for gardening or cutting flowers and are also used as raw materials for perfumes, cosmetics, and [...] Read more.
Rose (Rosa hybrida) is a major flower crop worldwide and has long been loved for its variety of colors and scents. Roses are mainly used for gardening or cutting flowers and are also used as raw materials for perfumes, cosmetics, and food. Essential oils, which are extracted from the flowers of plants, including roses, have various scents, and the essential oil market has been growing steadily owing to the growing awareness of the benefits of natural and organic products. Therefore, it is necessary to develop a system that stably supplies raw materials with uniform ingredients in line with the continuous increase in demand. In this study, conditions for the efficient induction of callus were established from the petals of the rose breeding line 15R-12-2, which has a strong scent developed by the National Institute of Horticultural and Herbal Science, Rural Development Administration. The highest callus induction rate (65%) was observed when the petals of the fully open flower (FOF) were placed on the SH11DP medium so that the abaxial surface was in contact with the medium. In addition, the VOCs contained in the petals of 15R-12-2 and the petal-derived callus were analyzed by HS-SPME-GC-MS. Thirty components, including esters and alcohols, were detected in the petal-derived callus. Among them, 2-ethylhexan-1-ol, which showed 59.01% relative content when extracted with hexane as a solvent, was the same component as detected in petals. Therefore, petal-derived callus is expected to be of high industrial value and can be suggested as an alternative pathway to obtaining VOCs. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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12 pages, 2786 KiB  
Article
Cytogenetic Study and Pollen Viability of Phalaenopsis Queen Beer ‘Mantefon’
by Samantha Serafin Sevilleno, Hye Ryun An, Raisa Aone M. Cabahug-Braza, Yun-Jae Ahn and Yoon-Jung Hwang
Plants 2023, 12(15), 2828; https://doi.org/10.3390/plants12152828 - 31 Jul 2023
Viewed by 1012
Abstract
Intergeneric and interspecific hybridization has been employed for the breeding of Phalaenopsis to transfer desirable traits between species, producing novel phenotypes with improved size, color, form, and flower-bearing ability. These characteristics are often enhanced; however, many of these hybrids are triploids and have [...] Read more.
Intergeneric and interspecific hybridization has been employed for the breeding of Phalaenopsis to transfer desirable traits between species, producing novel phenotypes with improved size, color, form, and flower-bearing ability. These characteristics are often enhanced; however, many of these hybrids are triploids and have reduced or complete sterility, for example, Phalaenopsis Queen Beer ‘Mantefon’, an important novelty-type cultivar in Asia, particularly in China, Japan, and Republic of Korea. Despite the increasing demand for the crop for ornamental purposes, little is known about its cytogenetics, which is essential for breeding and, consequently, crop improvement. In this study, karyotyping using fluorescence in situ hybridization, meiotic chromosome behavior analysis, pollen staining, and in vitro viability germination tests were performed to understand the cause of hybrid sterility and pollen abnormality in Phalaenopsis Queen Beer ‘Mantefon’ from a cytogenetic perspective. Viability tests revealed pollen infertility at all flower developmental stages, confirmed by the absence of pollen tube growth. Aberrant chromosomal behavior was observed in pollen mother cells (PMCs), frequently forming univalents, chromosomal bridges, and laggards during the entire meiotic process. PMCs were also divided irregularly into sporads with varying numbers of micronuclei, which may be responsible for pollen sterility in this cultivar. Altogether, the cytogenetic analyses provided insights into the pollen development of Phalaenopsis Queen Beer ‘Mantefon’ and the conceivable causes of its infertility. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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14 pages, 1530 KiB  
Article
Optimization of In Vitro Germination, Viability Tests and Storage of Paeonia ostii Pollen
by Mengchen Li, Fengfei Jiang, Linbo Huang, Hui Wang, Wenqing Song, Xiaoxiao Zhang, Yanlong Zhang and Lixin Niu
Plants 2023, 12(13), 2460; https://doi.org/10.3390/plants12132460 - 27 Jun 2023
Cited by 2 | Viewed by 1650
Abstract
Paeonia ostii is an important woody oil crop mainly cross-pollinated. However, the low yield has become an important factor restricting the industrial development of P. ostii. Cross-pollination has become one of the important measures to increase the seed yield. Therefore, conservation of pollen [...] Read more.
Paeonia ostii is an important woody oil crop mainly cross-pollinated. However, the low yield has become an important factor restricting the industrial development of P. ostii. Cross-pollination has become one of the important measures to increase the seed yield. Therefore, conservation of pollen with high vitality is crucial to ensure successful pollination of P. ostii. In this study, we found an effective methodological system to assess the viability, ability to germinate, and optimal storage conditions of P. ostii pollen grains. The optimal medium in vitro was 50 g/L sucrose, 100 mg/L boric acid, 50 g/L PEG6000, 100 mg/L potassium nitrate, 300 mg/L calcium nitrate, and 200 mg/L magnesium sulfate at pH 5.4. Optimal germination condition in vitro was achieved at 25 °C for 120 min, allowing easy observation of the germination percentage and length of the pollen tubes. In addition, the viability of pollen grains was assessed by comparing nine staining methods. Among them, MTT, TTC, benzidine-H2O2, and FDA were effective to distinguish between viable and non-viable pollen, and the results of the FDA staining method were similar to the pollen germination percentage in vitro. After evaluation of pollen storage, thawing and rehydration experiments showed that thawing at 4 °C for 30 min and rehydration at 25 °C for 30 min increased the germination percentage of pollen grains stored at low temperatures. The low-temperature storage experiments showed that 4 °C was suitable for short-term storage of P. ostii pollen grains, while −80 °C was suitable for long-term storage. This is the first report on the in vitro germination, viability tests, and storage of P. ostii pollen grains, which will provide useful information for P. ostii germplasm conservation and artificial pollination. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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17 pages, 6715 KiB  
Article
Pollen Morphology of Convolvulaceae from Southeastern Amazonian Cangas and Its Relevance for Interaction Networks and Paleoenvironmental Studies
by Luiza de Araújo Romeiro, Edilson Freitas da Silva, Liziane Vilela Vasconcelos, Karen da Silva Lopes, Léa Maria Medeiros Carreira and José Tasso Felix Guimarães
Plants 2023, 12(12), 2256; https://doi.org/10.3390/plants12122256 - 09 Jun 2023
Cited by 2 | Viewed by 1632
Abstract
Serra dos Carajás harbors a unique open plant community in Amazonia, known as canga vegetation, with several endemic species coexisting with the potential threat of large-scale iron ore mining. In this sense, Convolvulaceae occur in a wide variety of canga geoenvironments with multiple [...] Read more.
Serra dos Carajás harbors a unique open plant community in Amazonia, known as canga vegetation, with several endemic species coexisting with the potential threat of large-scale iron ore mining. In this sense, Convolvulaceae occur in a wide variety of canga geoenvironments with multiple flower visitors, but the scarcity of data on its pollen morphology prevents the correct association between Convolvulaceae species with floral visitors, as well as the precise identification of their habitats throughout the Quaternary. Therefore, this study aims to contribute to the taxonomic knowledge and refinement of the identification of insect-plant networks of endangered plants, including Ipomoea cavalcantei. Pollen grains were examined by light and scanning electron microscopy (LM and SEM, respectively), and the morphological parameters obtained were statistically analyzed using principal component analysis. Therefore, all species were differentiated based on aperture types and exine ornamentation. The set of morphological characters indicated that echinae morphology, easily identified under LM, was effective for the identification of Ipomoea species. This work represents the first robust pollen database for a precise identification at the species level of Convolvulaceae from southeastern Amazonian cangas. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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13 pages, 2874 KiB  
Article
Metabolomic and Transcriptomic Analysis Reveal the Role of Metabolites and Genes in Modulating Flower Color of Paphiopedilum micranthum
by Xinyan Deng, Chao Hu, Chengzhi Xie, Aixian Lu, Yibo Luo, Tao Peng and Weichang Huang
Plants 2023, 12(10), 2058; https://doi.org/10.3390/plants12102058 - 22 May 2023
Cited by 1 | Viewed by 1361
Abstract
Food-deceptive flowers primarily use visual signals (such as color) to mimic model plants and deceive insects into achieving pollination. Paphiopedilum micranthum is a food-deceptive orchid that has a pink labellum and two purple petals with a yellow base and has been proven to [...] Read more.
Food-deceptive flowers primarily use visual signals (such as color) to mimic model plants and deceive insects into achieving pollination. Paphiopedilum micranthum is a food-deceptive orchid that has a pink labellum and two purple petals with a yellow base and has been proven to be pollinated by bumblebees. However, the chemical and molecular bases of the floral color are not well understood. We conducted targeted metabolite profiling and transcriptomic analysis to determine the color signal and its genetic basis in P. micranthum. We found that both anthocyanins and carotenoids contribute significantly to the formation of floral color that determines the color signal. Higher concentrations of anthocyanins (cyanidin and peonidin) and carotenoids (primarily lutein and zeaxanthin) were detected in the petal compared to the labellum. The upregulation of structural genes of CHS, F3H, DFR and ANS on the anthocyanin biosynthesis pathway in petals was identified, as well as three genes of LCYE, BCH, and CCD4 on the carotenoid biosynthesis pathway. Furthermore, we discovered that three R2R3-MYBs and one bHLH transcription factors were co-expressed with the expression of different genes. These genes and transcription factors may be responsible for the spatial color difference of P. micranthum. Our study emphasizes that the color of this food-deceptive orchids is achieved through specific genes and transcription factors associated with the pigment biosynthesis pathway. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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22 pages, 17827 KiB  
Article
Transcriptome Analysis of the Late-Acting Self-Incompatibility Associated with RNase T2 Family in Camellia oleifera
by Chang Li, Mengqi Lu, Junqin Zhou, Sen Wang, Yi Long, Yan Xu and Xiaofeng Tan
Plants 2023, 12(10), 1932; https://doi.org/10.3390/plants12101932 - 09 May 2023
Cited by 1 | Viewed by 1446
Abstract
The Camellia oil tree (Camellia oleifera Abel.) is an important nonwood forest species in China, and the majority of its cultivars are late-acting self-incompatibility (LSI) types. Although several studies have examined the mechanism of LSI, the process is quite complicated and unclear. [...] Read more.
The Camellia oil tree (Camellia oleifera Abel.) is an important nonwood forest species in China, and the majority of its cultivars are late-acting self-incompatibility (LSI) types. Although several studies have examined the mechanism of LSI, the process is quite complicated and unclear. In this study, pollen tube growth and fruit setting of two Camellia oil tree cultivars Huashuo (HS) and Huajin (HJ) were investigated after non and self-pollination, and transcriptomic analysis of the ovaries was performed 48 h after self-pollination to identify the potential genes implicated in the LSI of Camellia oil trees. The results showed that the fruit set of HS was significantly higher than that of HJ after self-pollination. Transcriptomic analysis revealed that plant hormone signal transduction, the phosphatidylinositol signaling system, ATP-binding cassette (ABC) transporters, reactive oxygen species (ROS) metabolism, and Ca2+ signaling were mainly contributed in the LSI of reaction of Camellia oil tree. Moreover, nine RNase T2 genes were identified from the transcriptome analysis, which also showed that CoRNase7 participated in the self-incompatibility reaction in HS. Based on phylogenetic analysis, CoRNase6 was closely related to S-RNase from coffee, and CoRNase7 and CoRNase8 were closely related to S-RNase from Camellia sinensis. The 9 RNase T2 genes successfully produced proteins in prokaryotes. Subcellular localization indicated that CoRNase1 and CoRNase5 were cytoplasmic proteins, while CoRNase7 was a plasma membrane protein. These results screened the main metabolic pathways closely related to LSI in Camellia oil tree, and SI signal transduction might be regulated by a large molecular regulatory network. The discovery of T2 RNases provided evidence that Camellia oil tree might be under RNase-based gametophytic self-incompatibility. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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8 pages, 1558 KiB  
Communication
Unique Morphology of Sarcobatus baileyi Male Inflorescence and Its Botanical Implications
by Wenzhe Liu, Xiuping Xu and Xin Wang
Plants 2023, 12(9), 1917; https://doi.org/10.3390/plants12091917 - 08 May 2023
Viewed by 1189
Abstract
A typical angiosperm flower is usually bisexual, with entomophilous plants having four whorls of organs: the calyx, corolla, stamens, and gynoecium. The flower is usually colorful, and thus, distinct from the dull-colored reproductive organs of gymnosperms; however, this formula is not applicable to [...] Read more.
A typical angiosperm flower is usually bisexual, with entomophilous plants having four whorls of organs: the calyx, corolla, stamens, and gynoecium. The flower is usually colorful, and thus, distinct from the dull-colored reproductive organs of gymnosperms; however, this formula is not applicable to all flowers. For example, the male flower of Sarcobatus baileyi is reduced into only a single stamen. Such unusual flowers are largely poorly documented and underappreciated. To fill such a lacuna in our knowledge of the male reproductive organ of S. baileyi, we collected and studied materials of the male inflorescence of S. baileyi (Sarcobataceae). The outcomes of our Micro-CT (micro computed tomography), SEM (scanning electron microscopy), and paraffin sectioning indicate that a male inflorescence of S. baileyi is more comparable with the cone of conifers; its male flowers lack the perianth, are directly attached to a central axis and sheltered by peltate indusium-like shields. To understand the evolutionary logic underlying such a rarely seen male inflorescence, we also studied and compared it with a female cone of Cupressus sempervirens. Although the genera Sarcobatus and Cupressus belong to two distinct major plant groups (angiosperms and gymnosperms), they apply the same propagule-protecting strategy. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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14 pages, 3121 KiB  
Article
Screening of Early Flowering Lotus (Nelumbo nucifera Gaertn.) Cultivars and Effects of Different Cultivars on Flowering Period
by Huiyan Jiang, Junjie Chen, Guangyang Liu, Ping Zhou, Qijiang Jin, Yanjie Wang, Huan Guo, Ping Qian and Yingchun Xu
Plants 2023, 12(8), 1683; https://doi.org/10.3390/plants12081683 - 17 Apr 2023
Cited by 2 | Viewed by 1083
Abstract
Flowering time is an important trait that determines the breeding process of ornamental plants. The flowering period of lotus (Nelumbo nucifera Gaertn.) is mainly concentrated in June–August. During this period, the weather is hot and there are few tourists, which made many [...] Read more.
Flowering time is an important trait that determines the breeding process of ornamental plants. The flowering period of lotus (Nelumbo nucifera Gaertn.) is mainly concentrated in June–August. During this period, the weather is hot and there are few tourists, which made many lotus scenic spots difficult to operate. People have a strong demand for early flowering lotus cultivars. In this paper, 30 lotus cultivars with high ornamental value were selected as materials and their phenological periods were observed for two consecutive years in 2019 and 2020. A number of cultivars with early flowering potential and stable flowering periods, such as ‘Fenyanzi’, ‘Chengshanqiuyue’, ‘Xianghumingyue’ and ‘Wuzhilian’, were screened by K-Means clustering method. The relationship between accumulated temperature and flowering time of 19 lotus cultivars at different growth stages was analyzed. It was found that lotus cultivars with early flowering traits could adapt well to the changes of early environmental temperature and were not affected by low temperature. On the other hand, by analyzing the relationship between different traits and flowering time of three typical cultivars, such as rhizome weight, phenological period, etc., it shows that the nutrient content of the rhizome and the early morphology of plants will affect the flowering time. These results provide a reference for the formation of a systematic lotus early flowering cultivar breeding mechanism and the establishment of a perfect flowering regulation technology system, which can further improve the ornamental value of lotus and promote industrial development. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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12 pages, 1472 KiB  
Article
Pollinator Proboscis Length Plays a Key Role in Floral Integration of Honeysuckle Flowers (Lonicera spp.)
by Gan-Ju Xiang, Amparo Lázaro, Xiao-Kang Dai, Jing Xia and Chun-Feng Yang
Plants 2023, 12(8), 1629; https://doi.org/10.3390/plants12081629 - 12 Apr 2023
Cited by 1 | Viewed by 1271
Abstract
Pollinator-mediated selection is supposed to influence floral integration. However, the potential pathway through which pollinators drive floral integration needs further investigations. We propose that pollinator proboscis length may play a key role in the evolution of floral integration. We first assessed the divergence [...] Read more.
Pollinator-mediated selection is supposed to influence floral integration. However, the potential pathway through which pollinators drive floral integration needs further investigations. We propose that pollinator proboscis length may play a key role in the evolution of floral integration. We first assessed the divergence of floral traits in 11 Lonicera species. Further, we detected the influence of pollinator proboscis length and eight floral traits on floral integration. We then used phylogenetic structural equation models (PSEMs) to illustrate the pathway through which pollinators drive the divergence of floral integration. Results of PCA indicated that species significantly differed in floral traits. Floral integration increased along with corolla tube length, stigma height, lip length, and the main pollinators’ proboscis length. PSEMs revealed a potential pathway by which pollinator proboscis length directly selected on corolla tube length and stigma height, while lip length co-varied with stigma height. Compared to species with short corolla tubes, long-tube flowers may experience more intense pollinator-mediated selection due to more specialized pollination systems and thus reduce variation in the floral traits. Along elongation of corolla tube and stigma height, the covariation of other relevant traits might help to maintain pollination success. The direct and indirect pollinator-mediation selection collectively enhances floral integration. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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12 pages, 37804 KiB  
Article
Emergence of Corona Is Independent of the Four Whorls of Floral Organs in Narcissus tazetta
by Yanjun Ma, Xiaomeng Hu, Keke Fan, Na Zhang, Lili Shang, Yayun Deng, Tao Hu, Wenbo Zhang, Yan Wang and Zehui Jiang
Plants 2023, 12(7), 1458; https://doi.org/10.3390/plants12071458 - 27 Mar 2023
Viewed by 2094
Abstract
Plants of the genus Narcissus are well-known for their characteristic corona morphology, which structural origins have been a bone of contention among scholars. With “Jinzhanyintai” (JZ) and “Yulinglong” (YLL)—two major close-originated cultivars of Chinese narcissus (Narcissus tazetta L. var. chinensis Roem)—as materials, [...] Read more.
Plants of the genus Narcissus are well-known for their characteristic corona morphology, which structural origins have been a bone of contention among scholars. With “Jinzhanyintai” (JZ) and “Yulinglong” (YLL)—two major close-originated cultivars of Chinese narcissus (Narcissus tazetta L. var. chinensis Roem)—as materials, anatomic observation was made on floral organs during corona morphogenesis by dissection with hands under a stereomicroscope, paraffin section, scanning electron microscopy, and high-resolution X-ray tomography. It was uncovered that corona primordia of both cultivars appeared following the end of the differentiation of other floral organs, with differentiation sites located at the inner wall of the juncture of the base of tepals and the upper margin of the hypanthium. Affected by staminal filaments, the corona primordia of JZ experienced a three-stage differentiation process, namely blockage from the second whorl of stamens, blockage from the first whorl of stamens, and healing of corona primordia. However, the expanded spatial structure of the first whorl of petal-like stamens blocked the path of differentiation of YLL corona primordia, giving rise to slow differentiation of the corona primordia at the base of the first whorl of petal-like stamens and malformed differentiation of the corona primordia in the interval between the two whorls of petal-like stamens. Thus, a fragmented structure consisting of typical and fragmented coronas was formed. Furthermore, petal-like stamens of YLL in the lower part had a corona-like morphology. The spatio-temporal specificity of corona differentiation convincingly demonstrates that the corona is a structure independent of and different from the typical four whorls of floral organs, but also highly correlated with stamen. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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17 pages, 3855 KiB  
Article
Heteroblastic Inflorescence of Lamium amplexicaule L. in Egyptian Flora
by Wafaa M. Amer, Najla A. Al Shaye, Mahmoud O. Hassan and Maha H. Khalaf
Plants 2023, 12(5), 1028; https://doi.org/10.3390/plants12051028 - 24 Feb 2023
Viewed by 1197
Abstract
Lamium amplexicaule L. (Family: Lamiaceae) is a cosmopolitan weed whose eradication is challenging. The phenoplasticity of this species is related to its heteroblastic inflorescence, which has not received adequate research worldwide in its morphological and genetic aspects. This inflorescence hosts two flower types, [...] Read more.
Lamium amplexicaule L. (Family: Lamiaceae) is a cosmopolitan weed whose eradication is challenging. The phenoplasticity of this species is related to its heteroblastic inflorescence, which has not received adequate research worldwide in its morphological and genetic aspects. This inflorescence hosts two flower types, a cleistogamous (CL: closed flower) and a chasmogamous (CH: opened flower). This species subjected to detailed investigation is a model species to clarify: (1) the existence of the CL and CH flowers in relation to the time and individual plants. (2) the predominant flower morphs in Egypt. (3) the morphological and genetic variability between these morphs. Among the novel data retrieved from this work is the Presence of this species in three distinct morphs coexisting during winter. These morphs showed remarkable phenoplasticity, particularly in flower organs. Significant differences were observed between the three morphs in pollen fertility, nutlets productivity and sculpture, flowering time, and seed viability. These differences were extended to the genetic profile of these three morphs assessed by the inter simple sequence repeats (ISSRs) and start codon targeted (SCoT). This work highlights the urgent need to study the heteroblastic inflorescence of crop weeds to facilitate its eradication. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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13 pages, 1970 KiB  
Article
New Insights into the Mechanism of Spatiotemporal Scent Accumulation in Orchid Flowers
by Bao-Qiang Zheng, Xiao-Qing Li and Yan Wang
Plants 2023, 12(2), 304; https://doi.org/10.3390/plants12020304 - 09 Jan 2023
Viewed by 1339
Abstract
Orchid flowers have a unique structure that consists of three sepals and three petals, with one of the petals forming the labellum (lip) that can be differentiated into the hypochile and epichile. In orchids, the emission of floral scent is specific and spatially [...] Read more.
Orchid flowers have a unique structure that consists of three sepals and three petals, with one of the petals forming the labellum (lip) that can be differentiated into the hypochile and epichile. In orchids, the emission of floral scent is specific and spatially complex. Little is understood about the molecular and biochemical mechanisms of the differing scent emissions between the parts of orchid flowers. Here, we investigated this in the Cattleya hybrid KOVA, and our study showed that monoterpenes, including linalool and geraniol, are the main components responsible for the KOVA floral scent. The KOVA flower was scentless to the human nose before it reached full bloom, potentially because the 1-deoxy-d-xylulose 5-phosphate synthases (RcDXSs) and 4-hydroxy-3-methylbut-2-enyl diphosphate synthases (RcHDSs) that biosynthesize monoterpenes were highly expressed in flowers only when it reached full flowering. Additionally, the spatial expression profile of the monoterpene synthases (RcMTPSs), which were highly expressed in the basal region of the lip (hypochile), contributed to the highest monoterpene emissions from this part of the flower. This might have caused the hypochile to be more fragrant than the other parts of the flower. These findings enrich our understanding of the difference in scents between different flower parts in plants and provide information to breed novel orchid cultivars with special floral scents. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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13 pages, 1943 KiB  
Article
Spatio-Temporal Variations in Pollen Limitation and Floral Traits of an Alpine Lousewort (Pedicularis rhinanthoides) in Relation to Pollinator Availability
by Wenkui Dai, Anne Christine Ochola and Yongquan Li
Plants 2023, 12(1), 78; https://doi.org/10.3390/plants12010078 - 23 Dec 2022
Cited by 2 | Viewed by 1158
Abstract
Populations of the same plant species living in different locations but flowering at different times may vary in pollinator availability and floral traits. However, the spatial and temporal links between floral traits and pollination are rarely included in single studies. In this study, [...] Read more.
Populations of the same plant species living in different locations but flowering at different times may vary in pollinator availability and floral traits. However, the spatial and temporal links between floral traits and pollination are rarely included in single studies. In this study, three populations of an alpine lousewort, Pedicularis rhinanthoides Schrenk subsp. tibetica (Bonati) Tsoong, were surveyed to detect the variations in floral traits and pollinator activity. We hypothesized that floral divergence was spatio-temporally correlated with pollen limitation (PL) in relation to pollinators. Sampled plants from each population were divided into three groups, according to flowering stage: early, peak, and late. Pollen-supplementation experiments and investigations into pollinators, reproductive success, and floral traits were conducted on the plants from the different flowering stages and across the populations. Our results showed that the extent of PL varies across populations and among flowering stages. Populations in which more pollinators were recorded displayed a lower extent of PL. Furthermore, the temporal differences in PL showed a similar pattern for the three populations; the plants from the peak flowering stage suffered slighter PL than those from the other two stages. Nevertheless, some of the floral traits displayed similar spatial and temporal patterns to the PL, while the others only varied among the populations spatially. The results indicated that the performance of floral traits in a particular spatial–temporal situation shows they are well adapted to the corresponding pollination environment, which might help plants to optimize their reproductive fitness under different abiotic factors. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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18 pages, 3847 KiB  
Article
Palyno-Morphological Characteristics as a Systematic Approach in the Identification of Halophytic Poaceae Species from a Saline Environment
by Moona Nazish and Ashwaq T. Althobaiti
Plants 2022, 11(19), 2618; https://doi.org/10.3390/plants11192618 - 05 Oct 2022
Cited by 2 | Viewed by 2414
Abstract
Pollen morphology of 12 salt-tolerant grasses (Calamagrostis pseudophragmites, Cenchrus biflorus, Cenchrus ciliaris, Cenchrus pennisetiformis, Cymbopogon jwarancusa, Dactyloctenium aegyptium, Echinochloa colona, Echinochloa crus-galli, Saccharum griffithii, Saccharum ravennae, Saccharum spontaneum, and Urochloa ramosa [...] Read more.
Pollen morphology of 12 salt-tolerant grasses (Calamagrostis pseudophragmites, Cenchrus biflorus, Cenchrus ciliaris, Cenchrus pennisetiformis, Cymbopogon jwarancusa, Dactyloctenium aegyptium, Echinochloa colona, Echinochloa crus-galli, Saccharum griffithii, Saccharum ravennae, Saccharum spontaneum, and Urochloa ramosa) from the Salt Range was studied using scanning electron microscopy (SEM) and light microscopy (LM). The main aim was the elucidation of taxonomic significance of pollen morphology, which might be useful for taxonomists in the identification of halophytic Poaceae taxa. The described pollen morphology is a good source of taxonomic characteristics that can help in species and genera differentiation. The investigated variations in the pollen micromorphological features and exploration of new palynological traits support and strengthen the systematics of Poaceae. The pollen shape of all studied species was sub-spheroidal, and exine ornamentation includes microechinate-areolate (11 spp.) and microechinate (1 spp.). Two types of pollen apertures were reported, i.e., monoporate (11 spp.) and diporate (Cenchrus pennisetiformis). The annulus was found in all species while operculum was observed only in three species. The univariate and multivariate analyses were used to analyze the quantitative data. The highest pollen viability values (%) depicted the adaptability of Poaceae taxa in the salt region. Overall, the pollen characteristics in polar and equatorial view, apertures, annulus, operculum, and surface ornamentation of pollen grains of the family Poaceae are of great taxonomic significance for the species identification. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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17 pages, 5320 KiB  
Article
Pollen Morphology of Some Species from Genus Nitraria
by Maria Tomoshevich, Evgeny Banaev, Sofia Khozyaykina and Anna Erst
Plants 2022, 11(18), 2359; https://doi.org/10.3390/plants11182359 - 09 Sep 2022
Cited by 5 | Viewed by 3554
Abstract
An analysis of pollen grains (in Nitraria sibirica Pall., N. schoberi L., N. komarovii Iljin & Lava ex Bobrov, and N. pamirica L. Vassil.) was performed on natural material collected in Russia, Kazakhstan, and Tajikistan. Herbarium specimens from the collection at Komarov Botanical [...] Read more.
An analysis of pollen grains (in Nitraria sibirica Pall., N. schoberi L., N. komarovii Iljin & Lava ex Bobrov, and N. pamirica L. Vassil.) was performed on natural material collected in Russia, Kazakhstan, and Tajikistan. Herbarium specimens from the collection at Komarov Botanical Institute, Russian Academy of Sciences (N. tangutorum Bobrov and N. praevisa Bobrov) were examined, too. Pollen grains of two species—N. pamirica and N. praevisa—were studied for the first time. N. tangutorum and N. praevisa were found to have the perprolate pollen shape, whereas N. pamirica was found to have the subprolate shape. An intraspecific differentiation of N. sibirica was noted. Populations of N. sibirica (Taskarasu, Karatal, and Basshi) possess pollen grains of the subprolate or prolate shape, striate and perforate exine ornamentation, and a longer equatorial axis and a shorter polar axis than other specimens of N. sibirica. N. schoberi in all populations had anomalous shapes of some pollen grains. Overall, we demonstrated that the length ratio of the polar axis to the equatorial axis, characteristics of pollen in polar view, colpus morphology, and surface ornamentation of pollen grains in the genus Nitraria are of great taxonomic importance for the identification of species. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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13 pages, 5261 KiB  
Article
The Biomechanical Screening Game between Visitor Power and Staminode Operative Strength of Delphinium caeruleum (Ranunculaceae)
by Qin-Zheng Hou, Wen-Juan Shao, Nurbiye Ehmet, Guang Yang, Yu-Qin Zhong, Wen-Rui Min, Yi-Fan Xu and Ruo-Chun Gao
Plants 2022, 11(17), 2319; https://doi.org/10.3390/plants11172319 - 05 Sep 2022
Cited by 2 | Viewed by 1459
Abstract
During the evolution of angiosperm flowers, some floral traits may undergo certain changes in order to participate in screening. The stamens and pistils of Delphinium caeruleum are covered by two “door-like” staminodes, the evolutionary function of which, however, is quite unknown. In this [...] Read more.
During the evolution of angiosperm flowers, some floral traits may undergo certain changes in order to participate in screening. The stamens and pistils of Delphinium caeruleum are covered by two “door-like” staminodes, the evolutionary function of which, however, is quite unknown. In this study, we investigated whether D. caeruleum staminodes acted as visitor filters by assessing the respective strengths of staminodes and visitor insects (six bee species). We measured the operative strength required to open the staminodes and the strength that insects were capable of exerting using a biological tension sensor. Furthermore, we compared the strength required to open staminodes at different phases of the flowering period (male and female phases) and the strength of different visitors (visitors and non-visitors of D. caeruleum). The results showed that the strength needed to open staminodes in the male phase was significantly higher than that in the female phase. There was no significant difference between the strength exerted by visitors and required by staminodes of D. caeruleum in the male phase, but the visitor strength was significantly higher than that required to open staminodes in the female phase flowers. The strength of non-visitors was significantly lower than that required to open staminodes in the male phase. Furthermore, there was a significant positive association between the strength and the body weight of the bees. These results highlighted the observation that only strong visitors could press the two staminodes to access the sex organs and achieve successful pollination. Furthermore, these results revealed the function of pollinator screening by the staminodes of D. caeruleum. The biomechanical approach to the study of flowers allowed us to address relevant ecological and evolutionary questions of the plant–pollinator interaction and explore the functional modules within the flower structure in other plant species. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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27 pages, 8158 KiB  
Article
Functional Ecology of External Secretory Structures in Rivea ornata (Roxb.) Choisy (Convolvulaceae)
by Natthaphong Chitchak, Alyssa B. Stewart and Paweena Traiperm
Plants 2022, 11(15), 2068; https://doi.org/10.3390/plants11152068 - 08 Aug 2022
Cited by 3 | Viewed by 2244
Abstract
Plants have evolved numerous secretory structures that fulfill diverse roles and shape their interactions with other organisms. Rivea ornata (Roxb.) Choisy (Convolvulaceae) is one species that possesses various external secretory organs hypothesized to be ecologically important. This study, therefore, aimed to investigate five [...] Read more.
Plants have evolved numerous secretory structures that fulfill diverse roles and shape their interactions with other organisms. Rivea ornata (Roxb.) Choisy (Convolvulaceae) is one species that possesses various external secretory organs hypothesized to be ecologically important. This study, therefore, aimed to investigate five secretory structures (nectary disc, petiolar nectaries, calycinal glands, staminal hairs, and foliar glands) using micromorphology, anatomy, histochemistry, and field observations of plant–animal interactions in order to assess the functional contributions of these structures. Results show that the nectary disc and petiolar nectaries are complex working units consisting of at least epidermis and ground tissue, while the other structures are glandular trichomes. Various groups of metabolites (lipids, phenolic compounds, polysaccharides, terpenoids, flavonoids, and alkaloids) were detected in all structures, while starch grains were only found in the nectary disc, petiolar nectaries, and their adjacent tissues. Integrating preliminary observation of animal visitors with micromorphological, anatomical, and histochemical results, two hypotheses are proposed: (I) nectary disc and staminal hairs are important for pollination as they potentially attract and reward floral visitors, and (II) petiolar nectaries, calycinal glands, and foliar glands contribute to plant defense. Specifically, petiolar nectaries and calycinal glands provide protection from herbivores via guard ants, while calycinal and foliar glands may use plant metabolites to help prevent tissue damage from dehydration and insolation. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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11 pages, 2828 KiB  
Article
Morphological Variations between Korean and Southwestern Japanese Lilium leichtlinii Hook. f.
by Ji-Young Kim, Jong-Kuk Na and Jong-Hwa Kim
Plants 2022, 11(15), 2016; https://doi.org/10.3390/plants11152016 - 02 Aug 2022
Viewed by 1396
Abstract
This study aimed to examine detailed morphological variations within Lilium leichtlinii Hook. f. For investigation, two groups, Korean L. leichtlinii (KR group) and southwestern Japanese broad-leaved L. leichtlinii (JSW group), were compared. In total, 52 morphological characteristics (45 quantitative and 7 qualitative traits) [...] Read more.
This study aimed to examine detailed morphological variations within Lilium leichtlinii Hook. f. For investigation, two groups, Korean L. leichtlinii (KR group) and southwestern Japanese broad-leaved L. leichtlinii (JSW group), were compared. In total, 52 morphological characteristics (45 quantitative and 7 qualitative traits) were examined in 59 lily accessions (30 KR and 29 JSW). Forty quantitative traits showed significant heterogeneity (p < 0.05) between JSW and KR accessions, and all seven color-related qualitative traits also exhibited differences. Student’s t-tests and principal component analysis (PCA) revealed that major quantitative morphological differences between the two groups included plant height, internode length, upper leaf size, and number of new bulbs. Cluster analysis of 36 morphological traits showed that the KR and JSW accessions belonged to two distinct groups. All together, these results indicate that KR and JSW groups are distal within L. leichtlinii, suggesting that the two groups could be considered different varieties. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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15 pages, 1555 KiB  
Article
Phenotypic Selection in Halenia elliptica D. Don (Gentianaceae), an Alpine Biennial with Mixed Mating System
by Xiaojuan Huang, Minyu Chen, Linlin Wang, Mingliu Yang, Nacai Yang, Zhonghu Li and Yuanwen Duan
Plants 2022, 11(11), 1488; https://doi.org/10.3390/plants11111488 - 31 May 2022
Viewed by 1820
Abstract
The transition from outcrossing to selfing is a common evolutionary trend in flowering plants, and floral traits change significantly with the evolution of selfing. Whether or not plant traits are subjected to selection remains an open question in species with mixed mating systems. [...] Read more.
The transition from outcrossing to selfing is a common evolutionary trend in flowering plants, and floral traits change significantly with the evolution of selfing. Whether or not plant traits are subjected to selection remains an open question in species with mixed mating systems. We examined phenotypic selection in two populations of Halenia elliptica with different selfing rates. We found that the pollen–ovule ratio, seed size, plant height, spur length, and pollinator visitation rate in the population with the higher selfing rate were lower than those in the population with the lower selfing rate. Selfing provides reproductive assurance for populations when pollinator service is low, and the floral traits that are associated with selfing syndrome are evident in populations with a higher selfing rate but are subjected to weak selection in each of the two populations with different selfing rates. Directional selection for an early flowering time indicated that late blooming flowers could experience a risk of seed development in alpine environments, and for large plants, selection indicated that seed production could be limited by the available resources. The floral traits that are associated with pollinator attraction and specialization could be subjected to weak selection at the plant level as selfing evolves, and the selective pressures that are independent of pollinators might not change significantly; highlighting the selective biotic and abiotic pressures that shape the morphological traits of plant species and their independence from the mating system. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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14 pages, 3772 KiB  
Article
Microstructure of Croatian Wild Grapevine (Vitis vinifera subsp. sylvestris Gmel Hegi) Pollen Grains Revealed by Scanning Electron Microscopy
by Katarina Lukšić, Goran Zdunić, Ana Mucalo, Luka Marinov, Zorica Ranković-Vasić, Jelena Ivanović and Dragan Nikolić
Plants 2022, 11(11), 1479; https://doi.org/10.3390/plants11111479 - 31 May 2022
Cited by 5 | Viewed by 2007
Abstract
Wild grapevine (Vitis vinifera subsp. sylvestris Gmel Hegi) is dioecious with male and female plants, whereas domesticated grapevine is mostly hermaphrodite with self-fertile hermaphrodite flowers. The pollen morphology of wild grapevine has been poorly studied. There is no detailed palynological study of [...] Read more.
Wild grapevine (Vitis vinifera subsp. sylvestris Gmel Hegi) is dioecious with male and female plants, whereas domesticated grapevine is mostly hermaphrodite with self-fertile hermaphrodite flowers. The pollen morphology of wild grapevine has been poorly studied. There is no detailed palynological study of V. sylvestris in Croatia and neighboring countries. Here, scanning electron microscopy (SEM) was used to analyze the pollen of V. sylvestris from male and female individuals growing at two natural sites in Croatia. The selective APT3 marker was used to confirm the flower phenotype with the genetic background. SEM analysis showed that the pollen grains of V. sylvestris were isopolar and radially symmetrical, with foveolate perforated ornamentation, regardless of the flower type of the individuals. All male flowers were 3-colporate and prolate in shape, whereas female individuals varied from subprolate to spheroidal and had inaperturate pollen grains. Pollen shape, dimensions and exine ornamentation proved very informative, and here we address the most polymorphic traits in the analyzed V. sylvestris individuals. Principal component analysis (PCA) and clustering based on pollen morphology variables clearly differentiated individuals by their flower type, and no grouping specific to population was observed, pointing to the conserved pollen structure of V. sylvestris. The results indicate the need to continue the palynological study of V. sylvestris and serve as a good phenotypic basis for functional genetic studies on genes involved in pollen morphology and function. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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16 pages, 6119 KiB  
Article
Characterization of PISTILLATA-like Genes and Their Promoters from the Distyly Fagopyrum esculentum
by Wei You, Xiangjian Chen, Lingtian Zeng, Zhiyuan Ma and Zhixiong Liu
Plants 2022, 11(8), 1047; https://doi.org/10.3390/plants11081047 - 12 Apr 2022
Cited by 2 | Viewed by 1594
Abstract
Arabidopsis PISTILLATA (PI) encodes B-class MADS-box transcription factor (TF), and works together with APETALA3 (AP3) to specify petal and stamen identity. However, a small-scale gene duplication event of PI ortholog was observed in common buckwheat and resulted in [...] Read more.
Arabidopsis PISTILLATA (PI) encodes B-class MADS-box transcription factor (TF), and works together with APETALA3 (AP3) to specify petal and stamen identity. However, a small-scale gene duplication event of PI ortholog was observed in common buckwheat and resulted in FaesPI_1 and FaesPI_2. FaesPI_1 and FaesPI_2 were expressed only in the stamen of dimorphic flower (thrum and pin) of Fagopyrum esculentum. Moreover, intense beta-glucuronidase (GUS) staining was found in the entire stamen (filament and anther) in pFaesPI_1::GUS transgenic Arabidopsis, while GUS was expressed only in the filament of pFaesPI_2::GUS transgenic Arabidopsis. In addition, phenotype complementation analysis suggested that pFaesPI_1::FaesPI_1/pFaesPI_2::FaesPI_2 transgenic pi-1 Arabidopsis showed similar a flower structure with stamen-like organs or filament-like organs in the third whorl. This suggested that FaesPI_2 only specified filament development, but FaesPI_1 specified stamen development. Meanwhile, FaesPI_1 and FaesPI_2 were shown to function redundantly in regulating filament development, and both genes work together to require a proper stamen identity. The data also provide a clue to understanding the roles of PI-like genes involved in floral organ development during the early evolution of core eudicots and also suggested that FaesPI_1 and FaesPI_2 hold the potential application in bioengineering to develop a common buckwheat male sterile line. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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15 pages, 8140 KiB  
Article
Brief Pollination Assessment of a Critically Endangered Food-Deceptive Orchid (Cypripedium guttatum) Using a Network Approach
by Hakbong Lee, Heung-Sik Lee and Kee-Hwa Bae
Plants 2022, 11(6), 798; https://doi.org/10.3390/plants11060798 - 17 Mar 2022
Viewed by 2019
Abstract
The translocation of orchids (Orchidaceae) cannot be successful if one is unaware of their effective pollinators and plant–pollinator interactions. Cypripedium guttatum is a generalized food-deceptive orchid, which is highly threatened in the Republic of Korea, thus, requiring immediate translocation actions. Although effective pollinators [...] Read more.
The translocation of orchids (Orchidaceae) cannot be successful if one is unaware of their effective pollinators and plant–pollinator interactions. Cypripedium guttatum is a generalized food-deceptive orchid, which is highly threatened in the Republic of Korea, thus, requiring immediate translocation actions. Although effective pollinators of the orchid are well known in China, little is known about the pollinators in the Republic of Korea and the ecological context in which the orchid can be successfully pollinated. To briefly assess the pollination of C. guttatum prior to translocation, we conducted a one-month survey of general pollination and the community-wide plant–pollinator network properties. Over 21 h of observation, we found that an effective pollinator of the orchid was the sweat bee Lasioglossum virideglaucum. The network was significantly specialized and modular, but not significantly nested. L. virideglaucum (pollinator) and Arabis gemmifera (plant) were determined to be keystone species, based on network metrics. A total of six network modules were identified and the flower colors of the plant species belonging to the C. guttatum module were purple, white, and yellow. After comparing the daily network patterns, we found that pollination of the orchid was accomplished when various flowering plant species bloom, and the nestedness value was high. This study revealed that high plant and pollinator richness could increase the chance that the deceptive orchid would be pollinated. Our study suggests that the network properties of this food-deceptive orchid community could provide useful insight into understanding the ecologically suitable habitat for the translocation of the highly threatened orchid species C. guttatum. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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Review

Jump to: Research

20 pages, 839 KiB  
Review
Secondary Metabolites in Nectar-Mediated Plant-Pollinator Relationships
by Marta Barberis, Daniele Calabrese, Marta Galloni and Massimo Nepi
Plants 2023, 12(3), 550; https://doi.org/10.3390/plants12030550 - 25 Jan 2023
Cited by 8 | Viewed by 3916
Abstract
In recent years, our understanding of the complex chemistry of floral nectar and its ecological implications for plant-pollinator relationships has certainly increased. Nectar is no longer considered merely a reward for pollinators but rather a plant interface for complex interactions with insects and [...] Read more.
In recent years, our understanding of the complex chemistry of floral nectar and its ecological implications for plant-pollinator relationships has certainly increased. Nectar is no longer considered merely a reward for pollinators but rather a plant interface for complex interactions with insects and other organisms. A particular class of compounds, i.e., nectar secondary compounds (NSCs), has contributed to this new perspective, framing nectar in a more comprehensive ecological context. The aim of this review is to draft an overview of our current knowledge of NSCs, including emerging aspects such as non-protein amino acids and biogenic amines, whose presence in nectar was highlighted quite recently. After considering the implications of the different classes of NSCs in the pollination scenario, we discuss hypotheses regarding the evolution of such complex nectar profiles and provide cues for future research on plant-pollinator relationships. Full article
(This article belongs to the Special Issue Floral Biology 2.0)
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