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26 pages, 14731 KiB

Open AccessArticle

Acute NO₂ Stress Shortens the Median Survival Period of Bougainvillea glabra ‘Elizabeth Angus’ by Disrupting Tissue Structure and Photosynthetic Response Centers

by Yuxiang Liang, Xinchen Qian, Shuang Song, Qianqian Sheng and Zunling Zhu

Plants 2023, 12(23), 4028; https://doi.org/10.3390/plants12234028 - 30 Nov 2023

Viewed by 865

Abstract

The air pollutant NO₂ is one of the major constraints on plant growth, and the ecological value of the ornamental plant Bougainvillea glabra can be weakened by NO₂. In this study, an indoor 4 μL·L⁻¹ NO₂ simulated fumigation test [...] Read more.

The air pollutant NO₂ is one of the major constraints on plant growth, and the ecological value of the ornamental plant Bougainvillea glabra can be weakened by NO₂. In this study, an indoor 4 μL·L⁻¹ NO₂ simulated fumigation test was conducted with three treatments, CK (normal growth with clean air), T1 (4 μL·L⁻¹ NO₂ + 8 h/d), and T2 (4 μL·L⁻¹ NO₂ + 24 h/d), which were set up with considerations for time and concentration. The results demonstrated that most of the morphological parameters of B. glabra ‘Elizabeth Angus’, except for the floral organs, were decreased in the root, stem, leaf, and bract. Continuous fumigation significantly attenuated the growth rate and reduced the water and pigment contents of organs. Excessive NO₂ reduced the number and transfer rate of photoelectrons by destroying the photosynthetic reaction center, which in turn weakened photosynthesis, but the plants with intermittent fumigation recovered after fumigation. The Kaplan-Meier (K-M) survival curve displayed median survival periods of 41 and 55.5 h for T1 and T2, respectively, and the morphological structure and most of the indicators of photosynthetic reaction centers changed significantly during stress. Acute injury to B. glabra ‘Elizabeth Angus’ was caused by 4 μL·L⁻¹ NO₂, and B. glabra ‘Elizabeth Angus’ had limited ability to regulate high concentrations of NO₂ acute stress. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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24 pages, 14543 KiB

Open AccessArticle

Comparative Root Transcriptome Profiling and Gene Regulatory Network Analysis between Eastern and Western Carrot (Daucus carota L.) Cultivars Reveals Candidate Genes for Vascular Tissue Patterning

by Chaitra C. Kulkarni, Sarvamangala S. Cholin, Akhilesh K. Bajpai, Gabrijel Ondrasek, R. K. Mesta, Santosha Rathod and H. B. Patil

Plants 2023, 12(19), 3449; https://doi.org/10.3390/plants12193449 - 30 Sep 2023

Cited by 1 | Viewed by 1331

Abstract

Carrot (Daucus carota L.) is a highly consumed vegetable rich in carotenoids, known for their potent antioxidant, anti-inflammatory, and immune-protecting properties. While genetic and molecular studies have largely focused on wild and Western carrot cultivars (cvs), little is known about the evolutionary [...] Read more.

Carrot (Daucus carota L.) is a highly consumed vegetable rich in carotenoids, known for their potent antioxidant, anti-inflammatory, and immune-protecting properties. While genetic and molecular studies have largely focused on wild and Western carrot cultivars (cvs), little is known about the evolutionary interactions between closely related Eastern and Western cvs. In this study, we conducted comparative transcriptome profiling of root tissues from Eastern (UHSBC-23-1) and Western (UHSBC-100) carrot cv. to better understand differentially expressed genes (DEGs) associated with storage root development and vascular cambium (VC) tissue patterning. Through reference-guided TopHat mapping, we achieved an average mapping rate of 73.87% and identified a total of 3544 DEGs (p < 0.05). Functional annotation and gene ontology classification revealed 97 functional categories, including 33 biological processes, 19 cellular components, 45 metabolic processes, and 26 KEGG pathways. Notably, Eastern cv. exhibited enrichment in cell wall, plant-pathogen interaction, and signal transduction terms, while Western cv. showed dominance in photosynthesis, metabolic process, and carbon metabolism terms. Moreover, constructed gene regulatory network (GRN) for both cvs. obtained orthologs with 1222 VC-responsive genes of Arabidopsis thaliana. In Western cv, GRN revealed VC-responsive gene clusters primarily associated with photosynthetic processes and carbon metabolism. In contrast, Eastern cv. exhibited a higher number of stress-responsive genes, and transcription factors (e.g., MYB15, WRKY46, AP2/ERF TF connected via signaling pathways with NAC036) were identified as master regulators of xylem vessel differentiation and secondary cell wall thickening. By elucidating the comparative transcriptome profiles of Eastern and Western cvs. for the first time, our study provides valuable insights into the differentially expressed genes involved in root development and VC tissue patterning. The identification of key regulatory genes and their roles in these processes represents a significant advancement in our understanding of the evolutionary relations and molecular mechanisms underlying secondary growth of carrot and regulation by vascular cambium. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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17 pages, 1173 KiB

Open AccessArticle

Exploring Salinity Tolerance Mechanisms in Diverse Wheat Genotypes Using Physiological, Anatomical, Agronomic and Gene Expression Analyses

by Mohammed A. A. Hussein, Mesfer M. Alqahtani, Khairiah M. Alwutayd, Abeer S. Aloufi, Omnia Osama, Enas S. Azab, Mohamed Abdelsattar, Abdallah A. Hassanin and Salah A. Okasha

Plants 2023, 12(18), 3330; https://doi.org/10.3390/plants12183330 - 20 Sep 2023

Cited by 1 | Viewed by 1110

Abstract

Salinity is a widespread abiotic stress that devastatingly impacts wheat growth and restricts its productivity worldwide. The present study is aimed at elucidating biochemical, physiological, anatomical, gene expression analysis, and agronomic responses of three diverse wheat genotypes to different salinity levels. A salinity [...] Read more.

Salinity is a widespread abiotic stress that devastatingly impacts wheat growth and restricts its productivity worldwide. The present study is aimed at elucidating biochemical, physiological, anatomical, gene expression analysis, and agronomic responses of three diverse wheat genotypes to different salinity levels. A salinity treatment of 5000 and 7000 ppm gradually reduced photosynthetic pigments, anatomical root and leaf measurements and agronomic traits of all evaluated wheat genotypes (Ismailia line, Misr 1, and Misr 3). In addition, increasing salinity levels substantially decreased all anatomical root and leaf measurements except sclerenchyma tissue upper and lower vascular bundle thickness compared with unstressed plants. However, proline content in stressed plants was stimulated by increasing salinity levels in all evaluated wheat genotypes. Moreover, Na+ ions content and antioxidant enzyme activities in stressed leaves increased the high level of salinity in all genotypes. The evaluated wheat genotypes demonstrated substantial variations in all studied characters. The Ismailia line exhibited the uppermost performance in photosynthetic pigments under both salinity levels. Additionally, the Ismailia line was superior in the activity of superoxide dismutase (SOD), catalase activity (CAT), peroxidase (POX), and polyphenol oxidase (PPO) enzymes followed by Misr 1. Moreover, the Ismailia line recorded the maximum anatomical root and leaf measurements under salinity stress, which enhanced its tolerance to salinity stress. The Ismailia line and Misr 3 presented high up-regulation of H+ATPase, NHX2 HAK, and HKT genes in the root and leaf under both salinity levels. The positive physiological, anatomical, and molecular responses of the Ismailia line under salinity stress were reflected on agronomic performance and exhibited superior values of all evaluated agronomic traits. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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20 pages, 11969 KiB

Open AccessArticle

Differential Morpho-Physiological and Biochemical Responses of Duckweed Clones from Saudi Arabia to Salinity

by Mohammed Al-Dakhil, Walid Ben Romdhane, Salem Alghamdi and Ahmed Abdelrahim Mohamed Ali

Plants 2023, 12(18), 3206; https://doi.org/10.3390/plants12183206 - 08 Sep 2023

Cited by 2 | Viewed by 942

Abstract

Salinity affects the morphological, physiological, and biochemical characteristics of several plant species. The current study was conducted to investigate differential salt tolerance potentials among ten duckweed clones under different salt-stress conditions. Morphological and physiological parameters, including fronds length, fronds number, root length, root [...] Read more.

Salinity affects the morphological, physiological, and biochemical characteristics of several plant species. The current study was conducted to investigate differential salt tolerance potentials among ten duckweed clones under different salt-stress conditions. Morphological and physiological parameters, including fronds length, fronds number, root length, root number, Na⁺/K⁺, chlorophyll, proline contents, and fresh harvest weight, were recorded for each of the ten duckweed clones collected from different Saudi Arabia regions. Additionally, the expression patterns of seven salt-related genes were monitored in a salt-tolerant duckweed genotype. The results show that the Madinah-2 (Spirodela polyryiza) and Al-Qassim (Landoltia punctata) clones presented higher performances for all the tested morphological and physiological parameters compared to other genotypes under salt-stress conditions. At concentrations greater than 150 mM NaCl, these aforementioned traits were affected for all the genotypes tested, except Madinah-2 (S. polyryiza) and Al-Qassim (L. punctata) clones, both of which exhibited high tolerance behavior under high salt conditions (200 mM and 250 mM NaCl). The principal component analysis (PCA) showed that the first five principal components accounted for 94.8% of the total variance among the studied traits. Morphological and physiological traits are the major portions of PC1. Moreover, the expression pattern analysis of NHX, BZIP, ST, and KTrans transcript revealed their upregulation in the Al-Qassim clone under salt-stress conditions, suggesting that these genes play a role in this clone’s tolerance to salt-induced stress. Overall, this study indicates that the Al-Qassim clone could be used in a brackish-water duckweed-based treatment program with a simultaneous provision of valuable plant biomass. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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21 pages, 8480 KiB

Open AccessArticle

Integrating Full-Length Transcriptome and RNA Sequencing of Siberian Wildrye (Elymus sibiricus) to Reveal Molecular Mechanisms in Response to Drought Stress

by Qingqing Yu, Yi Xiong, Xiaoli Su, Yanli Xiong, Zhixiao Dong, Junming Zhao, Xin Shu, Shiqie Bai, Xiong Lei, Lijun Yan and Xiao Ma

Plants 2023, 12(14), 2719; https://doi.org/10.3390/plants12142719 - 21 Jul 2023

Viewed by 1083

Abstract

Drought is one of the most significant limiting factors affecting plant growth and development on the Qinghai–Tibet Plateau (QTP). Mining the drought-tolerant genes of the endemic perennial grass of the QTP, Siberian wildrye (Elymus sibiricus), is of great significance to creating [...] Read more.

Drought is one of the most significant limiting factors affecting plant growth and development on the Qinghai–Tibet Plateau (QTP). Mining the drought-tolerant genes of the endemic perennial grass of the QTP, Siberian wildrye (Elymus sibiricus), is of great significance to creating new drought-resistant varieties which can be used in the development of grassland livestock and restoring natural grassland projects in the QTP. To investigate the transcriptomic responsiveness of E. sibiricus to drought stress, PEG-induced short- and long-term drought stress was applied to two Siberian wildrye genotypes (drought-tolerant and drought-sensitive accessions), followed by third- and second-generation transcriptome sequencing analysis. A total of 40,708 isoforms were detected, of which 10,659 differentially expressed genes (DEGs) were common to both genotypes. There were 2107 and 2498 unique DEGs in the drought-tolerant and drought-sensitive genotypes, respectively. Additionally, 2798 and 1850 DEGs were identified in the drought-tolerant genotype only under short- and long-term conditions, respectively. DEGs numbering 1641 and 1330 were identified in the drought-sensitive genotype only under short- and long-term conditions, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that all the DEGs responding to drought stress in E. sibiricus were mainly associated with the mitogen-activated protein kinase (MAKP) signaling pathway, plant hormone signal transduction, the linoleic acid metabolism pathway, the ribosome pathway, and plant circadian rhythms. In addition, Nitrate transporter 1/Peptide transporter family protein 3.1 (NPF3.1) and Auxin/Indole-3-Acetic Acid (Aux/IAA) family protein 31(IAA31) also played an important role in helping E. sibiricus resist drought. This study used transcriptomics to investigate how E. sibiricus responds to drought stress, and may provide genetic resources and references for research into the molecular mechanisms of drought resistance in native perennial grasses and for breeding drought-tolerant varieties. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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13 pages, 1210 KiB

Open AccessArticle

Two Congeneric Shrubs from the Atacama Desert Show Different Physiological Strategies That Improve Water Use Efficiency under a Simulated Heat Wave

by Enrique Ostria-Gallardo, Estrella Zúñiga-Contreras, Danny E. Carvajal, Teodoro Coba de La Peña, Ernesto Gianoli and Luisa Bascuñán-Godoy

Plants 2023, 12(13), 2464; https://doi.org/10.3390/plants12132464 - 28 Jun 2023

Cited by 1 | Viewed by 1006

Abstract

Desert shrubs are keystone species for plant diversity and ecosystem function. Atriplex clivicola and Atriplex deserticola (Amaranthaceae) are native shrubs from the Atacama Desert that show contrasting altitudinal distribution (A. clivicola: 0–700 m.a.s.l.; A. deserticola: 1500–3000 m.a.s.l.). Both species possess [...] Read more.

Desert shrubs are keystone species for plant diversity and ecosystem function. Atriplex clivicola and Atriplex deserticola (Amaranthaceae) are native shrubs from the Atacama Desert that show contrasting altitudinal distribution (A. clivicola: 0–700 m.a.s.l.; A. deserticola: 1500–3000 m.a.s.l.). Both species possess a C4 photosynthetic pathway and Kranz anatomy, traits adaptive to high temperatures. Historical records and projections for the near future show trends in increasing air temperature and frequency of heat wave events in these species’ habitats. Besides sharing a C4 pathway, it is not clear how their leaf-level physiological traits associated with photosynthesis and water relations respond to heat stress. We studied their physiological traits (gas exchange, chlorophyll fluorescence, water status) before and after a simulated heat wave (HW). Both species enhanced their intrinsic water use efficiency after HW but via different mechanisms. A. clivicola, which has a higher LMA than A. deserticola, enhances water saving by closing stomata and maintaining RWC (%) and leaf Ψ_md potential at similar values to those measured before HW. After HW, A. deserticola showed an increase of A_max without concurrent changes in g_s and a significant reduction of RWC and Ψ_md. A. deserticola showed higher values of Chla fluorescence after HW. Thus, under heat stress, A. clivicola maximizes water saving, whilst A. deserticola enhances its photosynthetic performance. These contrasting (eco)physiological strategies are consistent with the adaptation of each species to their local environmental conditions at different altitudes. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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15 pages, 2484 KiB

Open AccessArticle

Effect of Reproductive Stage-Waterlogging on the Growth and Yield of Upland Cotton (Gossypium hirsutum)

by Uzzal Somaddar, Shamim Mia, Md. Ibrahim Khalil, Uttam Kumer Sarker, Md. Romij Uddin, Md. Salahuddin Kaysar, Apurbo Kumar Chaki, Arif Hasan Khan Robin, Abeer Hashem, Elsayed Fathi Abd_Allah, Chien Van Ha, Aarti Gupta, Jong-In Park, Lam-Son Phan Tran and Gopal Saha

Plants 2023, 12(7), 1548; https://doi.org/10.3390/plants12071548 - 03 Apr 2023

Cited by 2 | Viewed by 1918

Abstract

The reproductive stage of cotton (Gossypium sp.) is highly sensitive to waterlogging. The identification of potential elite upland cotton (Gossypium hirsutum) cultivar(s) having higher waterlogging tolerance is crucial to expanding cotton cultivation in the low-lying areas. The present study was [...] Read more.

The reproductive stage of cotton (Gossypium sp.) is highly sensitive to waterlogging. The identification of potential elite upland cotton (Gossypium hirsutum) cultivar(s) having higher waterlogging tolerance is crucial to expanding cotton cultivation in the low-lying areas. The present study was designed to investigate the effect of waterlogging on the reproductive development of four elite upland cotton cultivars, namely, Rupali-1, CB-12, CB-13, and DM-3, against four waterlogging durations (e.g., 0, 3, 6, and 9-day). Waterlogging stress significantly impacted morpho-physiological, biochemical, and yield attributes of cotton. Two cotton cultivars, e.g., CB-12 and Rupali-1, showed the lowest reduction in plant height (6 and 9%, respectively) and boll weight (8 and 5%, respectively) at the highest waterlogging duration of 9 days. Physiological and biochemical data revealed that higher leaf chlorophyll, proline, and relative water contents, and lower malondialdehyde contents, particularly in CB-12 and Rupali-1, were positively correlated with yield. Notably, CB-12 and Rupali-1 had higher seed cotton weight (90.34 and 83.10 g, respectively), lint weight (40.12 and 39.32 g, respectively), and seed weight (49.47 and 43.78 g, respectively) per plant than CB-13 and DM-3 in response to the highest duration of waterlogging of 9 days. Moreover, extensive multivariate analyses like Spearman correlation and the principle component analysis revealed that CB-12 and Rupali-1 had greater coefficients in yield and physiological attributes at 9-day waterlogging, whereas CB-13 and DM-3 were sensitive cultivars in response to the same levels of waterlogging. Thus, CB-12 and Rupali-1 might be well adapted to the low-lying waterlogging-prone areas for high and sustained yield. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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18 pages, 1013 KiB

Open AccessArticle

Exogenous Calcium Reinforces Photosynthetic Pigment Content and Osmolyte, Enzymatic, and Non-Enzymatic Antioxidants Abundance and Alleviates Salt Stress in Bread Wheat

by Mervat Sh Sadak, Rania S. Hanafy, Fatma M. A. M. Elkady, Asmaa M. Mogazy and Magdi T. Abdelhamid

Plants 2023, 12(7), 1532; https://doi.org/10.3390/plants12071532 - 01 Apr 2023

Cited by 15 | Viewed by 1848

Abstract

One of the main environmental stresses that hinder crop development as well as yield is salt stress, while the use of signal molecules such as calcium (Ca) has a substantial impact on reducing the detrimental effects of salt on different crop types. Therefore, [...] Read more.

One of the main environmental stresses that hinder crop development as well as yield is salt stress, while the use of signal molecules such as calcium (Ca) has a substantial impact on reducing the detrimental effects of salt on different crop types. Therefore, a factorial pot experiment in a completely randomized design was conducted to examine the beneficial role of Ca (0, 2.5, and 5 mM) in promoting the physiological, biochemical, and growth traits of the wheat plant under three salt conditions viz. 0, 30, and 60 mM NaCl. Foliar application of Ca increased the growth of salt-stressed wheat plants through increasing photosynthetic pigments, IAA, proline, and total soluble sugars contents and improving antioxidant enzymes in addition to non-enzymatic antioxidants glutathione, phenol and flavonoids, β-carotene, and lycopene contents, thus causing decreases in the over-accumulation of free radicals (ROS). The application of Ca increased the activity of antioxidant enzymes in wheat plants such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), which scavenge reactive oxygen species (ROS) and relieved salt stress. An additional salt tolerance mechanism by Ca increases the non-antioxidant activity of plants by accumulating osmolytes such as free amino acids, proline, and total soluble sugar, which maintain the osmotic adjustment of plants under salinity stress. Exogenous Ca application is a successful method for increasing wheat plants’ ability to withstand salt stress, and it has a considerable impact on the growth of wheat under salt stress. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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12 pages, 1493 KiB

Open AccessArticle

Accumulation of Toxic Arsenic by Cherry Radish Tuber (Raphanus sativus var. sativus Pers.) and Its Physiological, Metabolic and Anatomical Stress Responses

by Daniela Pavlíková, Milan Pavlík, Veronika Zemanová, Milan Novák, Petr Doležal, Petre I. Dobrev, Václav Motyka and Kamil Kraus

Plants 2023, 12(6), 1257; https://doi.org/10.3390/plants12061257 - 10 Mar 2023

Cited by 7 | Viewed by 1334

Abstract

In a pot experiment, cherry radish (Raphanus sativus var. sativus Pers. ‘Viola’) was cultivated under two levels of As soil contamination—20 and 100 mg/kg. The increasing As content in tubers with increasing soil contamination led to changes in free amino acids (AAs) [...] Read more.

In a pot experiment, cherry radish (Raphanus sativus var. sativus Pers. ‘Viola’) was cultivated under two levels of As soil contamination—20 and 100 mg/kg. The increasing As content in tubers with increasing soil contamination led to changes in free amino acids (AAs) and phytohormone metabolism and antioxidative metabolites. Changes were mainly observed under conditions of high As contamination (As100). The content of indole-3-acetic acid in tubers varied under different levels of As stress, but As100 contamination led to an increase in its bacterial precursor indole-3-acetamide. A decrease in cis-zeatin-9-riboside-5′-monophosphate content and an increase in jasmonic acid content were found in this treatment. The free AA content in tubers was also reduced. The main free AAs were determined to be transport AAs (glutamate—Glu, aspartate, glutamine—Gln, asparagine) with the main portion being Gln. The Glu/Gln ratio—a significant indicator of primary N assimilation in plants—decreased under the As100 treatment condition. A decrease in antioxidative metabolite content—namely that of ascorbic acid and anthocyanins—was observed in this experiment. A decline in anthocyanin content is related to a decrease in aromatic AA content which is crucial for secondary metabolite production. The changes in tubers caused by As contamination were reflected in anatomical changes in the radish tubers and roots. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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25 pages, 1907 KiB

Open AccessArticle

Comparative Analysis of the Response to Polyethylene Glycol-Simulated Drought Stress in Roots from Seedlings of “Modern” and “Ancient” Wheat Varieties

by Ilva Licaj, Maria Chiara Di Meo, Anna Fiorillo, Simone Samperna, Mauro Marra and Mariapina Rocco

Plants 2023, 12(3), 428; https://doi.org/10.3390/plants12030428 - 17 Jan 2023

Cited by 3 | Viewed by 1977

Abstract

Durum wheat is widely cultivated in the Mediterranean, where it is the basis for the production of high added-value food derivatives such as pasta. In the next few years, the detrimental effects of global climate change will represent a serious challenge to crop [...] Read more.

Durum wheat is widely cultivated in the Mediterranean, where it is the basis for the production of high added-value food derivatives such as pasta. In the next few years, the detrimental effects of global climate change will represent a serious challenge to crop yields. For durum wheat, the threat of climate change is worsened by the fact that cultivation relies on a few genetically uniform, elite varieties, better suited to intensive cultivation than “traditional” ones but less resistant to environmental stress. Hence, the renewed interest in “ancient” traditional varieties are expected to be more tolerant to environmental stress as a source of genetic resources to be exploited for the selection of useful agronomic traits such as drought tolerance. The aim of this study was to perform a comparative analysis of the effect and response of roots from the seedlings of two durum wheat cultivars: Svevo, a widely cultivated elite variety, and Saragolla, a traditional variety appreciated for its organoleptic characteristics, to Polyethylene glycol-simulated drought stress. The effect of water stress on root growth was analyzed and related to biochemical data such as hydrogen peroxide production, electrolyte leakage, membrane lipid peroxidation, proline synthesis, as well as to molecular data such as qRT-PCR analysis of drought responsive genes and proteomic analysis of changes in the protein repertoire of roots from the two cultivars. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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15 pages, 2458 KiB

Open AccessArticle

Exogenous Proline Improves Salt Tolerance of Alfalfa through Modulation of Antioxidant Capacity, Ion Homeostasis, and Proline Metabolism

by Shuaiqi Guo, Xuxia Ma, Wenqi Cai, Yuan Wang, Xueqin Gao, Bingzhe Fu and Shuxia Li

Plants 2022, 11(21), 2994; https://doi.org/10.3390/plants11212994 - 07 Nov 2022

Cited by 10 | Viewed by 2397

Abstract

Alfalfa (Medicago sativa L.) is an important forage crop, and its productivity is severely affected by salt stress. Although proline is a compatible osmolyte that plays an important role in regulating plant abiotic stress resistance, the basic mechanism of proline requires further [...] Read more.

Alfalfa (Medicago sativa L.) is an important forage crop, and its productivity is severely affected by salt stress. Although proline is a compatible osmolyte that plays an important role in regulating plant abiotic stress resistance, the basic mechanism of proline requires further clarification regarding the effect of proline in mitigating the harmful effects of salinity. Here, we investigate the protective effects and regulatory mechanisms of proline on salt tolerance of alfalfa. The results show that exogenous proline obviously promotes seed germination and seedling growth of salt-stressed alfalfa. Salt stress results in stunted plant growth, while proline application alleviates this phenomenon by increasing photosynthetic capacity and antioxidant enzyme activities and decreasing cell membrane damage and reactive oxygen species (ROS) accumulation. Plants with proline treatment maintain a better K⁺/Na⁺ ratio by reducing Na⁺ accumulation and increasing K⁺ content under salt stress. Additionally, proline induces the expression of genes related to antioxidant biosynthesis (Cu/Zn-SOD and APX) and ion homeostasis (SOS1, HKT1, and NHX1) under salt stress conditions. Proline metabolism is mainly regulated by ornithine-δ-aminotransferase (OAT) and proline dehydrogenase (ProDH) activities and their transcription levels, with the proline-treated plants displaying an increase in proline content under salt stress. In addition, OAT activity in the ornithine (Orn) pathway rather than Δ¹-pyrroline-5-carboxylate synthetase (P5CS) activity in the glutamate (Glu) pathway is strongly increased under salt stress, made evident by the sharp increase in the expression level of the OAT gene compared to P5CS1 and P5CS2. Our study provides new insight into how exogenous proline improves salt tolerance in plants and that it might be used as a significant practical strategy for cultivating salt-tolerant alfalfa. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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14 pages, 2665 KiB

Open AccessArticle

Mitigating the Adverse Effects of Semi-Arid Climate on Capsicum Cultivation by Using the Retractable Roof Production System

by Giao N. Nguyen and Neil Lantzke

Plants 2022, 11(20), 2794; https://doi.org/10.3390/plants11202794 - 21 Oct 2022

Cited by 4 | Viewed by 1622

Abstract

Capsicum (Capsicum annuum L.) belongs to the Solanaceae family and is an economically important vegetable crop. However, the crop is very sensitive to adverse weather conditions such as high temperatures and excessive sunlight, which cause flower and young fruit to drop and [...] Read more.

Capsicum (Capsicum annuum L.) belongs to the Solanaceae family and is an economically important vegetable crop. However, the crop is very sensitive to adverse weather conditions such as high temperatures and excessive sunlight, which cause flower and young fruit to drop and sunscald to mature fruits. Using protected cultivation such as shade covers or net houses is a feasible agronomic approach to protect the crop from high light intensity, which increases plant growth, reduces fruit damage, and increases marketable fruit yield and quality. Low-cost protected cropping options such as fixed-roof net houses have proved cost-effective and suitable for fruiting vegetable production in semi-arid climatic regions. However, this structure type is unable to protect the crops from rainfall, is prone to cyclone damage and is inflexible to accommodate various vegetable crops which have different requirements for healthy and productive growth. This study was conducted in Carnarvon, which has semi-arid climatic conditions and is a key horticultural district of Western Australia, to compare the Retractable Roof Production System (RRPS) and open field (OF) conditions in the production of capsicum. The data showed that the RRPS modified the internal light, temperature and humidity in favour of the capsicum crop. The RRPS-grown capsicum had higher plant height and lower canopy temperature on hot days than those in the OF. The mean marketable fruit yield of capsicum varieties grown in the RRPS was significantly higher than those in the OF with fruit yields of 97 t ha⁻¹ and 39.1 t ha⁻¹, respectively, but the fruit quality remained unchanged. Overall, the data suggest that the RRPS altered the internal microenvironment and enhanced capsicum crop growth, physiology and fruit yield by setting climatic parameters to automatically control the opening and closing of the roof, the insect net and side curtains, and activation of the fogging system. The future perspective of the deployment of RRPS for capsicum production under climatic conditions in Carnarvon was also discussed. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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17 pages, 5457 KiB

Open AccessArticle

Physiological Changes of Arabica Coffee under Different Intensities and Durations of Water Stress in the Brazilian Cerrado

by Patrícia Carvalho da Silva, Walter Quadros Ribeiro Junior, Maria Lucrecia Gerosa Ramos, Omar Cruz Rocha, Adriano Delly Veiga, Nathalia Henriques Silva, Lemerson de Oliveira Brasileiro, Charles Cardoso Santana, Guilherme Filgueiras Soares, Juaci Vitória Malaquias and Christina Cleo Vinson

Plants 2022, 11(17), 2198; https://doi.org/10.3390/plants11172198 - 25 Aug 2022

Cited by 4 | Viewed by 1844

Abstract

Coffee farmers have faced problems due to drought periods, with irrigation being necessary. In this sense, this study aimed to evaluate the responses to different levels and durations of water deficit in arabica coffee genotypes in the Cerrado region. The experiment consisted of [...] Read more.

Coffee farmers have faced problems due to drought periods, with irrigation being necessary. In this sense, this study aimed to evaluate the responses to different levels and durations of water deficit in arabica coffee genotypes in the Cerrado region. The experiment consisted of three Coffea arabica genotypes and five water regimes: full irrigation (FI 100 and FI 50—full irrigation with 100% and 50% replacement of evapotranspiration, respectively), water deficit (WD 100 and WD 50—water deficit from June to September, with 100% and 50% replacement of evapotranspiration, respectively) and rainfed (without irrigation). The variables evaluated were gas exchange, relative water content (RWC) and productivity. The results showed that during stress, plants under the FI water regime showed higher gas exchange and RWC, differently from what occurred in the WD and rainfed treatments; however, after irrigation, coffee plants under WDs regained their photosynthetic potential. Rainfed and WD 50 plants had more than 50% reduction in RWC compared to FIs. The Iapar 59 cultivar was the most productive genotype and the E237 the lowest. Most importantly, under rainfed conditions, the plants showed lower physiological and productive potential, indicating the importance of irrigation in Coffea arabica in the Brazilian Cerrado. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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14 pages, 1952 KiB

Open AccessArticle

Assessing Silicon-Mediated Growth Performances in Contrasting Rice Cultivars under Salt Stress

by Uzzal Somaddar, Hridoy Chandra Dey, Sarah Khanam Mim, Uttam Kumer Sarker, Md. Romij Uddin, Nasar Uddin Ahmed, Mohammad Golam Mostofa and Gopal Saha

Plants 2022, 11(14), 1831; https://doi.org/10.3390/plants11141831 - 13 Jul 2022

Cited by 7 | Viewed by 2147

Abstract

Silicon (Si) application has great potential to improve salt tolerance in a variety of crop plants. However, it is unclear how Si influences the responses of contrasting rice cultivars when exposed to excessive salt. Here, we investigated the functions of Si in alleviating [...] Read more.

Silicon (Si) application has great potential to improve salt tolerance in a variety of crop plants. However, it is unclear how Si influences the responses of contrasting rice cultivars when exposed to excessive salt. Here, we investigated the functions of Si in alleviating the negative effects of salt stress on two contrasting rice cultivars, namely BRRI dhan48 (salt-sensitive) and Binadhan-10 (salt-tolerant). Rice seedlings was pre-treated with three doses of Si (as silicic acid; 0, 1 and 2 mM) for 14 days at one-day interval before being exposed to salt stress (10 dSm⁻¹) in a sustained water bath system. The results demonstrated that the seedlings of BRRI dhan48 and Binadhan-10, respectively exhibited substantial reductions in shoot height (16 and 9%), shoot fresh weight (64 and 43%) and shoot dry weight (50 and 39%) under salinity. Intriguingly, BRRI dhan48 pre-treated with 1 and 2 mM Si, respectively, showed a higher increase in shoot height (SH) (by 25.90 and 26.08%) as compared with Binadhan-10 (by 3 and 8%) under salt stress compared with their respective controls. Data revealed that a comparatively higher improvement in the growth performances of the salt-induced Si pre-treated BRRI dhan48 than that of Binadhan-10. For example, 1 and 2 mM of Si treatments significantly attributed to elevated leaf relative water content (RWC) (13 and 22%), proline (138 and 165%), chlorophyll a (42 and 44%), chlorophyll b (91 and 72%), total chlorophyll (58 and 53%) and carotenoids (33 and 29%), and recovery in the reductions of electrolyte leakage (13 and 21%), malondialdehyde content (23 and 30%) and shoot Na⁺/K⁺ ratio (22 and 52%) in BRRI dhan48 compared with Si-untreated control plants under salt stress. In addition, we found salt-tolerant Binadhan-10 also had enhanced RWC (9 and 19%), proline (12 and 26%) with pre-treatment with 1 and 2 mM of Si, respectively, under salt stress, while no significant differences were noticed in the case of photosynthetic pigments and Na⁺/K⁺ ratio. Our results showed that Si supplementation potentiated higher salt-tolerance ability in the salt-sensitive BRRI dhan48 as compared with salt-tolerant Binadhan-10. Thus, Si application could be highly beneficial in the growth recovery of the salinity-affected salt-sensitive high yielding rice cultivars in the saline-prone areas. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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11 pages, 264 KiB

Open AccessArticle

Direct and Indirect Selection for Grain Yield and Grain Weight in Late Generations of Bread Wheat under Drought Stress and Normal Irrigation Environments

by Rasha E. Mahdy, Dikhnah Ashehri, Hanan Ali Alatawi, Hadba Al-Amrah and Ezzat E. Mahdy

Plants 2022, 11(12), 1604; https://doi.org/10.3390/plants11121604 - 18 Jun 2022

Cited by 3 | Viewed by 1322

Abstract

Two cycles of pedigree selection for grain yield/plant (GY/P) and grain weight (GW) (100-grain weight) were imposed under drought stress and normal irrigation to study the direct and indirect selection of GY/P and GW in bread wheat. The selection started in the F [...] Read more.

Two cycles of pedigree selection for grain yield/plant (GY/P) and grain weight (GW) (100-grain weight) were imposed under drought stress and normal irrigation to study the direct and indirect selection of GY/P and GW in bread wheat. The selection started in the F₆-generation (Cycle₀-C₀) of bread wheat (Triticum aestivum L.) traced back to the cross (Giza 164/Sids 4) of two Egyptian cultivars. The narrow sense heritability was higher under drought than under normal irrigation and increased by selection. Under drought, the observed direct gain after two cycles of selection for GW was 21.51% (p ≤ 0.01), and accompanied with an indirect gain in GY/P of 15.52%. The observed direct gain for GY/P was 17.98% and the indirect gain in GW was 13.81%. Under normal irrigation, the observed direct gain for GW was 12.86% and the indirect gain for GY/P was 16.04%. The direct gain in GY/P was 16.04% and the indirect gain in GW was 11.95%. The genotypic correlations were different in both environments before and after selection. Single trait selection was effective in improving the selection criterion, and selection greatly affected gene associations. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

Review

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17 pages, 1736 KiB

Open AccessReview

Selenium Regulates Antioxidant, Photosynthesis, and Cell Permeability in Plants under Various Abiotic Stresses: A Review

by Haodong Liu, Chunmei Xiao, Tianci Qiu, Jie Deng, Hua Cheng, Xin Cong, Shuiyuan Cheng, Shen Rao and Yue Zhang

Plants 2023, 12(1), 44; https://doi.org/10.3390/plants12010044 - 22 Dec 2022

Cited by 22 | Viewed by 2638

Abstract

Plant growth is affected by various abiotic stresses, including water, temperature, light, salt, and heavy metals. Selenium (Se) is not an essential nutrient for plants but plays important roles in alleviating the abiotic stresses suffered by plants. This article summarizes the Se uptake [...] Read more.

Plant growth is affected by various abiotic stresses, including water, temperature, light, salt, and heavy metals. Selenium (Se) is not an essential nutrient for plants but plays important roles in alleviating the abiotic stresses suffered by plants. This article summarizes the Se uptake and metabolic processes in plants and the functions of Se in response to water, temperature, light, salt, and heavy metal stresses in plants. Se promotes the uptake of beneficial substances, maintains the stability of plasma membranes, and enhances the activity of various antioxidant enzymes, thus alleviating adverse effects in plants under abiotic stresses. Future research directions on the relationship between Se and abiotic stresses in plants are proposed. This article will further deepen our understanding of the relationship between Se and plants. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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22 pages, 6702 KiB

Open AccessReview

Strigolactone: An Emerging Growth Regulator for Developing Resilience in Plants

by Ameena Fatima Alvi, Zebus Sehar, Mehar Fatma, Asim Masood and Nafees A. Khan

Plants 2022, 11(19), 2604; https://doi.org/10.3390/plants11192604 - 03 Oct 2022

Cited by 20 | Viewed by 3553

Abstract

Improving plant resilience to changing environmental conditions is the primary focus of today’s scientific research globally. It is essential to find various strategies for the better survival of plants with higher resistance potential to climate change. Strigolactones (SLs) are multifunctional β-carotene derivative molecules [...] Read more.

Improving plant resilience to changing environmental conditions is the primary focus of today’s scientific research globally. It is essential to find various strategies for the better survival of plants with higher resistance potential to climate change. Strigolactones (SLs) are multifunctional β-carotene derivative molecules that determine a range of plant growth and development aspects, such as root architecture, shoot branching, chlorophyll synthesis, and senescence. SLs facilitate strong defense responses against drought, salinity, heavy metal, nutrient starvation, and heat stress. The SLs trigger other hormonal-responsive pathways and determine plant resilience against stressful environments. This review focuses on the mechanisms regulated by SLs and interaction with other plant hormones to regulate plant developmental processes and SLs’ influence on the mitigation of plant damage under abiotic stresses. A better understanding of the signaling and perception of SLs may lead to the path for the sustainability of plants in the changing environmental scenario. The SLs may be considered as an opening door toward sustainable agriculture. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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25 pages, 1050 KiB

Open AccessReview

Chilling Tolerance in Maize: Insights into Advances—Toward Physio-Biochemical Responses’ and QTL/Genes’ Identification

by Yun Ma, Renxiang Tan and Jiuran Zhao

Plants 2022, 11(16), 2082; https://doi.org/10.3390/plants11162082 - 09 Aug 2022

Cited by 6 | Viewed by 2563

Abstract

Maize, a major staple cereal crop in global food supply, is a thermophilic and short-day C4 plant sensitive to low-temperature stress. A low temperature is among the most severe agro-meteorological hazards in maize-growing areas. This review covers the latest research and progress in [...] Read more.

Maize, a major staple cereal crop in global food supply, is a thermophilic and short-day C4 plant sensitive to low-temperature stress. A low temperature is among the most severe agro-meteorological hazards in maize-growing areas. This review covers the latest research and progress in the field of chilling tolerance in maize in the last 40 years. It mainly focuses on how low-temperature stress affects the maize membrane and antioxidant systems, photosynthetic physiology, osmoregulatory substances and hormone levels. In addition, the research progress in identifying cold-tolerance QTLs (quantitative trait loci) and genes to genetically improve maize chilling toleranceis comprehensively discussed. Based on previous research, this reviewprovides anoutlook on potential future research directions and offers a reference for researchers in the maize cold-tolerance-related field. Full article

(This article belongs to the Special Issue Plant Physiological, Biochemical, and Molecular Responses to Abiotic Stresses 2.0)

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