International Journal of Molecular Sciences

13 pages, 1690 KiB

Open AccessArticle

Effect of Exogenous Plant Growth Regulators and Rejuvenation Measures on the Endogenous Hormone and Enzyme Activity Responses of Acer mono Maxim in Cuttage Rooting

by Xinxin Zhou, Ruyue Li, Hailong Shen and Ling Yang

Int. J. Mol. Sci. 2023, 24(15), 11883; https://doi.org/10.3390/ijms241511883 - 25 Jul 2023

Viewed by 1314

Abstract

The cuttage rooting method for Acer species is difficult to achieve a good efficacy as trees maintain good characteristics at the rejuvenation stage, thus improving the rooting of Acer species. The addition of exogenous hormones and rejuvenation can improve the rooting effect of [...] Read more.

The cuttage rooting method for Acer species is difficult to achieve a good efficacy as trees maintain good characteristics at the rejuvenation stage, thus improving the rooting of Acer species. The addition of exogenous hormones and rejuvenation can improve the rooting effect of cuttings; however, the specific regulatory mechanism is still unclear. Here, Acer mono Maxim rejuvenation and non-rejuvenation cuttings were used as test subjects, to investigate the effects of exogenous hormones on the activities of endogenous hormones and antioxidant enzymes in the rooting process of young cuttings. The results showed that exogenous growth-regulating substances significantly improved the rooting rate of A. mono. Exogenous hormones naphthylacetic acid (NAA) + indolebutyric acid (IBA) increased the initial levels of the endogenous hormones, indoleacetic acid (IAA) and abscisic acid (ABA), and the enzyme activities of peroxidase (POD) and polyphenol oxidase (PPO). Rejuvenation treatment prolonged the time of increase in ABA content and indoleacetic acid oxidase (IAAO) activity at the root primordium induction stage, while increasing trans-zeatin riboside (ZR) content and decreasing POD enzyme activity in cuttings. These results demonstrate that A. mono cuttings can achieve the purpose of improving the rooting rate by adding the exogenous hormone (NAA + IBA), which is closely related to the changes of endogenous hormone content and enzyme activity, and these changes of A. mono rejuvenation cuttings are different from non-rejuvenation cuttings. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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17 pages, 5363 KiB

Open AccessArticle

Genome-Wide Identification and Expression Profiles of C-Repeat Binding Factor Transcription Factors in Betula platyphylla under Abiotic Stress

by Xiang Zhang, Jiajie Yu, Ruiqi Wang, Wenxuan Liu, Song Chen, Yiran Wang, Yue Yu, Guanzheng Qu and Su Chen

Int. J. Mol. Sci. 2023, 24(13), 10573; https://doi.org/10.3390/ijms241310573 - 24 Jun 2023

Cited by 7 | Viewed by 1009

Abstract

CBF (C-repeat binding factor) transcription factor subfamily belongs to AP2/ERF (Apetala 2/ethylene-responsive factor) transcription factor family, known for playing a vital role in plant abiotic stress response. Although some CBF transcription factors have been identified in several species, such as Arabidopsis, tobacco, [...] Read more.

CBF (C-repeat binding factor) transcription factor subfamily belongs to AP2/ERF (Apetala 2/ethylene-responsive factor) transcription factor family, known for playing a vital role in plant abiotic stress response. Although some CBF transcription factors have been identified in several species, such as Arabidopsis, tobacco, tomato and poplar, research of CBF focus mainly on model plant Arabidopsis and have not been reported in Betula platyphylla yet. In this study, a total of 20 BpCBF subfamily members were identified. The conserved domains, physicochemical properties, exon-intron gene structure and the structure of conserved protein motifs of BpCBFs were analyzed via bioinformatic tools. The collinearity analysis of CBF genes was performed between Betula platyphylla and Arabidopsis thaliana, Betula platyphylla, and Populus trichocarpa. The cis-acting elements in the promoter region of BpCBFs were identified, which were mainly environmental stress-related and hormone-related element components. In this case, the expression patterns of the 20 BpCBFs upon ABA or salt treatment were investigated. Most of these transcription factors were responsive to ABA or salt stress in different plant tissues. The up-regulation trend upon cold treatment of the six cold-responsive genes validated by qRT-PCR was consistent with the result of RNA-seq. BpCBF7 showed transcription activating activity. This study sheds light on the responses of BpCBFs to abiotic stress and provides a reference for further study of CBF transcription factors in woody plants. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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19 pages, 981 KiB

Open AccessReview

Microbiome-Mediated Protection against Pathogens in Woody Plants

by Qin Xiong, Jun Yang and Siyi Ni

Int. J. Mol. Sci. 2023, 24(22), 16118; https://doi.org/10.3390/ijms242216118 - 09 Nov 2023

Cited by 1 | Viewed by 1127

Abstract

Pathogens, especially invasive species, have caused significant global ecological, economic, and social losses in forests. Plant disease research has traditionally focused on direct interactions between plants and pathogens in an appropriate environment. However, recent research indicates that the microbiome can interact with the [...] Read more.

Pathogens, especially invasive species, have caused significant global ecological, economic, and social losses in forests. Plant disease research has traditionally focused on direct interactions between plants and pathogens in an appropriate environment. However, recent research indicates that the microbiome can interact with the plant host and pathogens to modulate plant resistance or pathogen pathogenicity, thereby altering the outcome of plant–pathogen interactions. Thus, this presents new opportunities for studying the microbial management of forest diseases. Compared to parallel studies on human and crop microbiomes, research into the forest tree microbiome and its critical role in forest disease progression has lagged. The rapid development of microbiome sequencing and analysis technologies has resulted in the rapid accumulation of a large body of evidence regarding the association between forest microbiomes and diseases. These data will aid the development of innovative, effective, and environmentally sustainable methods for the microbial management of forest diseases. Herein, we summarize the most recent findings on the dynamic structure and composition of forest tree microbiomes in belowground and aboveground plant tissues (i.e., rhizosphere, endosphere, and phyllosphere), as well as their pleiotropic impact on plant immunity and pathogen pathogenicity, highlighting representative examples of biological control agents used to modulate relevant tree microbiomes. Lastly, we discuss the potential application of forest tree microbiomes in disease control as well as their future prospects and challenges. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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16 pages, 972 KiB

Open AccessReview

Interaction of Phytohormones and External Environmental Factors in the Regulation of the Bud Dormancy in Woody Plants

by Zhaoyu Chen, Yadi Chen, Lanxi Shi, Li Wang and Weixing Li

Int. J. Mol. Sci. 2023, 24(24), 17200; https://doi.org/10.3390/ijms242417200 - 06 Dec 2023

Cited by 1 | Viewed by 1020

Abstract

Bud dormancy and release are essential phenomena that greatly assist in adapting to adverse growing conditions and promoting the holistic growth and development of perennial plants. The dormancy and release process of buds in temperate perennial trees involves complex interactions between physiological and [...] Read more.

Bud dormancy and release are essential phenomena that greatly assist in adapting to adverse growing conditions and promoting the holistic growth and development of perennial plants. The dormancy and release process of buds in temperate perennial trees involves complex interactions between physiological and biochemical processes influenced by various environmental factors, representing a meticulously orchestrated life cycle. In this review, we summarize the role of phytohormones and their crosstalk in the establishment and release of bud dormancy. External environmental factors, such as light and temperature, play a crucial role in regulating bud germination. We also highlight the mechanisms of how light and temperature are involved in the regulation of bud dormancy by modulating phytohormones. Moreover, the role of nutrient factors, including sugar, in regulating bud dormancy is also discussed. This review provides a foundation for enhancing our understanding of plant growth and development patterns, fostering agricultural production, and exploring plant adaptive responses to adversity. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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20 pages, 4626 KiB

Open AccessArticle

Genome-Wide Identification, Characterization, and Expression Analysis of the Copper-Containing Amine Oxidase Gene Family in Mangrove Kandelia obovata

by Quaid Hussain, Ting Ye, Chenjing Shang, Sihui Li, Jackson Nkoh Nkoh, Wenyi Li and Zhangli Hu

Int. J. Mol. Sci. 2023, 24(24), 17312; https://doi.org/10.3390/ijms242417312 - 09 Dec 2023

Viewed by 1489

Abstract

Copper-containing amine oxidases (CuAOs) are known to have significant involvement in the process of polyamine catabolism, as well as serving crucial functions in plant development and response to abiotic stress. A genome-wide investigation of the CuAO protein family was previously carried [...] Read more.

Copper-containing amine oxidases (CuAOs) are known to have significant involvement in the process of polyamine catabolism, as well as serving crucial functions in plant development and response to abiotic stress. A genome-wide investigation of the CuAO protein family was previously carried out in sweet orange (Citrus sinensis) and sweet cherry (Prunus avium L.). Six CuAO (KoCuAO1-KoCuAO6) genes were discovered for the first time in the Kandelia obovata (Ko) genome through a genome-wide analysis conducted to better understand the key roles of the CuAO gene family in Kandelia obovata. This study encompassed an investigation into various aspects of gene analysis, including gene characterization and identification, subcellular localization, chromosomal distributions, phylogenetic tree analysis, gene structure analysis, motif analysis, duplication analysis, cis-regulatory element identification, domain and 3D structural variation analysis, as well as expression profiling in leaves under five different treatments of copper (CuCl₂). Phylogenetic analysis suggests that these KoCuAOs, like sweet cherry, may be subdivided into three subgroups. Examining the chromosomal location revealed an unequal distribution of the KoCuAO genes across four out of the 18 chromosomes in Kandelia obovata. Six KoCuAO genes have coding regions with 106 and 159 amino acids and exons with 4 and 12 amino acids. Additionally, we discovered that the 2.5 kb upstream promoter region of the KoCuAOs predicted many cis elements linked to phytohormones and stress responses. According to the expression investigations, CuCl₂ treatments caused up- and downregulation of all six genes. In conclusion, our work provides a comprehensive overview of the expression pattern and functional variety of the Kandelia obovata CuAO gene family, which will facilitate future functional characterization of each KoCuAO gene. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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13 pages, 5577 KiB

Open AccessArticle

PagMYB205 Negatively Affects Poplar Salt Tolerance through Reactive Oxygen Species Scavenging and Root Vitality Modulation

by Lieding Zhou, Xuhui Huan, Kai Zhao, Xia Jin, Jia Hu, Shuhui Du, Youzhi Han and Shengji Wang

Int. J. Mol. Sci. 2023, 24(20), 15437; https://doi.org/10.3390/ijms242015437 - 22 Oct 2023

Cited by 1 | Viewed by 957

Abstract

Salt stress is one of the major abiotic stresses that limits plant growth and development. The MYB transcription factor family plays essential roles in plant growth and development, as well as stress tolerance processes. In this study, the cDNA of the 84K poplar [...] Read more.

Salt stress is one of the major abiotic stresses that limits plant growth and development. The MYB transcription factor family plays essential roles in plant growth and development, as well as stress tolerance processes. In this study, the cDNA of the 84K poplar (Populus abla × Populus glandulosa) was used as a template to clone the full length of the PagMYB205 gene fragment, and transgenic poplar lines with PagMYB205 overexpression (OX) or inhibited expression (RNAi, RNA interference) were cultivated. The role of PagMYB205 in poplar growth and development and salt tolerance was detected using morphological and physiological methods. The full-length CDS sequence of PagMYB205 was 906 bp, encoding 301 amino acids, and the upstream promoter sequence contained abiotic stress-related cis-acting elements. The results of subcellular localization and transactivation assays showed that the protein had no self-activating activity and was localized in the nucleus. Under salt stress, the rooting rate and root vitality of RNAi were higher than OX and wild type (WT). However, the malondialdehyde (MDA) content of the RNAi lines was significantly lower than that of the wild-type (WT) and OX lines, but the reactive oxygen species (ROS) scavenging ability, such as the peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) enzyme activities, was dramatically more powerful. Most significantly of all, the RNAi3 line with the lowest expression level of PagMYB205 had the lowest MDA content, the best enzyme activity and root vitality, and the best salt stress tolerance compared to the other lines. The above results suggest that the transcription factor PagMYB205 could negatively regulate salt stress tolerance by regulating antioxidant enzyme activity and root vitality. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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29 pages, 10508 KiB

Open AccessArticle

Network Analysis of Metabolome and Transcriptome Revealed Regulation of Different Nitrogen Concentrations on Hybrid Poplar Cambium Development

by Shuang Zhang, Lina Cao, Ruhui Chang, Heng Zhang, Jiajie Yu, Chunming Li, Guanjun Liu, Junxin Yan and Zhiru Xu

Int. J. Mol. Sci. 2024, 25(2), 1017; https://doi.org/10.3390/ijms25021017 - 13 Jan 2024

Viewed by 715

Abstract

Secondary development is a key biological characteristic of woody plants and the basis of wood formation. Exogenous nitrogen can affect the secondary growth of poplar, and some regulatory mechanisms have been found in the secondary xylem. However, the effect of nitrogen on cambium [...] Read more.

Secondary development is a key biological characteristic of woody plants and the basis of wood formation. Exogenous nitrogen can affect the secondary growth of poplar, and some regulatory mechanisms have been found in the secondary xylem. However, the effect of nitrogen on cambium has not been reported. Herein, we investigated the effects of different nitrogen concentrations on cambium development using combined transcriptome and metabolome analysis. The results show that, compared with 1 mM NH₄NO₃ (M), the layers of hybrid poplar cambium cells decreased under the 0.15 mM NH₄NO₃ (L) and 0.3 mM NH₄NO₃ (LM) treatments. However, there was no difference in the layers of hybrid poplar cambium cells under the 3 mM NH₄NO₃ (HM) and 5 mM NH₄NO₃ (H) treatments. Totals of 2365, 824, 649 and 398 DEGs were identified in the M versus (vs.) L, M vs. LM, M vs. HM and M vs. H groups, respectively. Expression profile analysis of the DEGs showed that exogenous nitrogen affected the gene expression involved in plant hormone signal transduction, phenylpropanoid biosynthesis, the starch and sucrose metabolism pathway and the ubiquitin-mediated proteolysis pathway. In M vs. L, M vs. LM, M vs. HM and M vs. H, differential metabolites were enriched in flavonoids, lignans, coumarins and saccharides. The combined analysis of the transcriptome and metabolome showed that some genes and metabolites in plant hormone signal transduction, phenylpropanoid biosynthesis and starch and sucrose metabolism pathways may be involved in nitrogen regulation in cambium development, whose functions need to be verified. In this study, from the point of view that nitrogen influences cambium development to regulate wood formation, the network analysis of the transcriptome and metabolomics of cambium under different nitrogen supply levels was studied for the first time, revealing the potential regulatory and metabolic mechanisms involved in this process and providing new insights into the effects of nitrogen on wood development. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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17 pages, 6036 KiB

Open AccessArticle

Effect of T-DNA Integration on Growth of Transgenic Populus × euramericana cv. Neva Underlying Field Stands

by Zijie Zhang, Yali Huang, Yan Dong, Yachao Ren, Kejiu Du, Jinmao Wang and Minsheng Yang

Int. J. Mol. Sci. 2023, 24(16), 12952; https://doi.org/10.3390/ijms241612952 - 19 Aug 2023

Viewed by 1050

Abstract

Multigene cotransformation has been widely used in the study of genetic improvement in crops and trees. However, little is known about the unintended effects and causes of multigene cotransformation in poplars. To gain insight into the unintended effects of T-DNA integration during multigene [...] Read more.

Multigene cotransformation has been widely used in the study of genetic improvement in crops and trees. However, little is known about the unintended effects and causes of multigene cotransformation in poplars. To gain insight into the unintended effects of T-DNA integration during multigene cotransformation in field stands, here, three lines (A1–A3) of Populus × euramericana cv. Neva (PEN) carrying Cry1Ac-Cry3A-BADH genes and three lines (B1–B3) of PEN carrying Cry1Ac-Cry3A-NTHK1 genes were used as research objects, with non-transgenic PEN as the control. Experimental stands were established at three common gardens in three locations and next generation sequencing (NGS) was used to identify the insertion sites of exogenous genes in six transgenic lines. We compared the growth data of the transgenic and control lines for four consecutive years. The results demonstrated that the tree height and diameter at breast height (DBH) of transgenic lines were significantly lower than those of the control, and the adaptability of transgenic lines in different locations varied significantly. The genotype and the experimental environment showed an interaction effect. A total of seven insertion sites were detected in the six transgenic lines, with B3 having a double-site insertion and the other lines having single copies. There are four insertion sites in the gene region and three insertion sites in the intergenic region. Analysis of the bases near the insertion sites showed that AT content was higher than the average chromosome content in four of the seven insertion sites within 1000 bp. Transcriptome analysis suggested that the differential expression of genes related to plant hormone transduction and lignin synthesis might be responsible for the slow development of plant height and DBH in transgenic lines. This study provides an integrated analysis of the unintended effects of transgenic poplar, which will benefit the safety assessment and reasonable application of genetically modified trees. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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14 pages, 4189 KiB

Open AccessArticle

Effects of Zinc Oxide Nanoparticles on Growth, Development, and Flavonoid Synthesis in Ginkgo biloba

by Qingjie Wang, Shiyuan Xu, Lei Zhong, Xiya Zhao and Li Wang

Int. J. Mol. Sci. 2023, 24(21), 15775; https://doi.org/10.3390/ijms242115775 - 30 Oct 2023

Viewed by 1214

Abstract

Ginkgo biloba is a highly valuable medicinal plant known for its rich secondary metabolites, including flavonoids. Zinc oxide nanoparticles (ZnO-NPs) can be used as nanofertilizers and nano-growth regulators to promote plant growth and development. However, little is known about the effects of ZnO-NPs [...] Read more.

Ginkgo biloba is a highly valuable medicinal plant known for its rich secondary metabolites, including flavonoids. Zinc oxide nanoparticles (ZnO-NPs) can be used as nanofertilizers and nano-growth regulators to promote plant growth and development. However, little is known about the effects of ZnO-NPs on flavonoids in G. biloba. In this study, G. biloba was treated with different concentrations of ZnO-NPs (25, 50, 100 mg/L), and it was found that 25 mg/L of ZnO-NPs enhanced G. biloba fresh weight, dry weight, zinc content, and flavonoids, while 50 and 100 mg/L had an inhibitory effect on plant growth. Furthermore, quantitative reverse transcription (qRT)-PCR revealed that the increased total flavonoids and flavonols were mainly due to the promotion of the expression of flavonol structural genes such as GbF3H, GbF3′H, and GbFLS. Additionally, when the GbF3H gene was overexpressed in tobacco and G. biloba calli, an increase in total flavonoid content was observed. These findings indicate that 25 mg/L of ZnO-NPs play a crucial role in G. biloba growth and the accumulation of flavonoids, which can potentially promote the yield and quality of G. biloba in production. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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17 pages, 6697 KiB

Open AccessArticle

An Insight of Betula platyphylla SWEET Gene Family through Genome-Wide Identification, Expression Profiling and Function Analysis of BpSWEET1c under Cold Stress

by Hao Zhang, Yuting Ding, Kaiye Yang, Xinyu Wang, Wenshuo Gao, Qingjun Xie, Zhongyuan Liu and Caiqiu Gao

Int. J. Mol. Sci. 2023, 24(17), 13626; https://doi.org/10.3390/ijms241713626 - 04 Sep 2023

Viewed by 942

Abstract

SWEET proteins play important roles in plant growth and development, sugar loading in phloem and resistance to abiotic stress through sugar transport. In this study, 13 BpSWEET genes were identified from birch genome. Collinearity analysis showed that there were one tandem repeating gene [...] Read more.

SWEET proteins play important roles in plant growth and development, sugar loading in phloem and resistance to abiotic stress through sugar transport. In this study, 13 BpSWEET genes were identified from birch genome. Collinearity analysis showed that there were one tandem repeating gene pair (BpSWEET1b/BpSWEET1c) and two duplicative gene pairs (BpSWEET17a/BpSWEET17b) in the BpSWEET gene family. The BpSWEET gene promoter regions contained several cis-acting elements related to stress resistance, for example: hormone-responsive and low-temperature-responsive cis-elements. Analysis of transcriptome data showed that BpSWEET genes were highly expressed in several sink organs, and the most BpSWEET genes were rapidly up-regulated under cold stress. BpSWEET1c, which was highly expressed in cold stress, was selected for further analysis. It was found that BpSWEET1c was located on the cell membrane. After 6 h of 4 °C stress, sucrose content in the leaves and roots of transient overexpressed BpSWEET1c was significantly higher than that of the control. MDA content in roots was significantly lower than that of the control. These results indicate that BpSWEET1c may play a positive role in the response to cold stress by promoting the metabolism and transport of sucrose. In conclusion, 13 BpSWEET genes were identified from the whole genome level. Most of the SWEET genes of birch were expressed in the sink organs and could respond to cold stress. Transient overexpression of BpSWEET1c changed the soluble sugar content and improved the cold tolerance of birch. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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17 pages, 4718 KiB

Open AccessArticle

Genome-Wide Analysis of Strictosidine Synthase-like Gene Family Revealed Their Response to Biotic/Abiotic Stress in Poplar

by Ruiqi Wang, Wenna Zhao, Wenjing Yao, Yuting Wang, Tingbo Jiang and Huanzhen Liu

Int. J. Mol. Sci. 2023, 24(12), 10117; https://doi.org/10.3390/ijms241210117 - 14 Jun 2023

Cited by 1 | Viewed by 1227

Abstract

The strictosidine synthase-like (SSL) gene family is a small plant immune-regulated gene family that plays a critical role in plant resistance to biotic/abiotic stresses. To date, very little has been reported on the SSL gene in plants. In this study, a [...] Read more.

The strictosidine synthase-like (SSL) gene family is a small plant immune-regulated gene family that plays a critical role in plant resistance to biotic/abiotic stresses. To date, very little has been reported on the SSL gene in plants. In this study, a total of thirteen SSLs genes were identified from poplar, and these were classified into four subgroups based on multiple sequence alignment and phylogenetic tree analysis, and members of the same subgroup were found to have similar gene structures and motifs. The results of the collinearity analysis showed that poplar SSLs had more collinear genes in the woody plants Salix purpurea and Eucalyptus grandis. The promoter analysis revealed that the promoter region of PtrSSLs contains a large number of biotic/abiotic stress response elements. Subsequently, we examined the expression patterns of PtrSSLs following drought, salt, and leaf blight stress, using RT-qPCR to validate the response of PtrSSLs to biotic/abiotic stresses. In addition, the prediction of transcription factor (TF) regulatory networks identified several TFs, such as ATMYB46, ATMYB15, AGL20, STOP1, ATWRKY65, and so on, that may be induced in the expression of PtrSSLs in response to adversity stress. In conclusion, this study provides a solid basis for a functional analysis of the SSL gene family in response to biotic/abiotic stresses in poplar. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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23 pages, 6421 KiB

Open AccessArticle

Comprehensive Time-Course Transcriptome Reveals the Crucial Biological Pathways Involved in the Seasonal Branch Growth in Siberian Elm (Ulmus pumila)

by Luo-Yan Zhang, Cheng Yang, Zhi-Cheng Wu, Xue-Jie Zhang and Shou-Jin Fan

Int. J. Mol. Sci. 2023, 24(19), 14976; https://doi.org/10.3390/ijms241914976 - 07 Oct 2023

Cited by 1 | Viewed by 856

Abstract

Timber, the most prevalent organic material on this planet, is the result of a secondary xylem emerging from vascular cambium. Yet, the intricate processes governing its seasonal generation are largely a mystery. To better understand the cyclic growth of vascular tissues in elm, [...] Read more.

Timber, the most prevalent organic material on this planet, is the result of a secondary xylem emerging from vascular cambium. Yet, the intricate processes governing its seasonal generation are largely a mystery. To better understand the cyclic growth of vascular tissues in elm, we undertook an extensive study examining the anatomy, physiology, and genetic expressions in Ulmus pumila. We chose three robust 15-year-old elm trees for our study. The cultivars used in this study were collected from the Inner Mongolia Autonomous Region in China and nurtured in the tree farm of Shandong Normal University. Monthly samples of 2-year-old elm branches were taken from the tree from February to September. Marked seasonal shifts in elm branch vascular tissues were observed by phenotypic observation: In February, the cambium of the branch emerged from dormancy, spurring growth. By May, elms began generating secondary xylem, or latewood, recognized by its tiny pores and dense cell structure. From June to August, there was a marked increase in the thickness of the secondary xylem. Transcriptome sequencing provides a potential molecular mechanism for the thickening of elm branches and their response to stress. In February, the tree enhanced its genetic responses to cold and drought stress. The amplified expression of CDKB, CYCB, WOX4, and ARF5 in the months of February and March reinforced their essential role in the development of the vascular cambium in elm. Starting in May, the elm deployed carbohydrates as a carbon resource to synthesize the abundant cellulose and lignin necessary for the formation of the secondary wall. Major genes participating in cellulose (SUC and CESA homologs), xylan (UGD, UXS, IRX9, IRX10, and IRX14), and lignin (PAL, C4H, 4CL, HCT, C3H, COMT, and CAD) biosynthetic pathways for secondary wall formation were up-regulated by May or/and June. In conclusion, our findings provided a foundation for an in-depth exploration of the molecular processes dictating the seasonal growth of elm timber. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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18 pages, 10147 KiB

Open AccessArticle

Brassinosteroids Regulate the Water Deficit and Latex Yield of Rubber Trees

by Bingbing Guo, Mingyang Liu, Hong Yang, Longjun Dai and Lifeng Wang

Int. J. Mol. Sci. 2023, 24(16), 12857; https://doi.org/10.3390/ijms241612857 - 16 Aug 2023

Cited by 2 | Viewed by 1021

Abstract

Brassinolide (BR) is an important plant hormone that regulates the growth and development of plants and the formation of yield. The yield and quality of latex from Hevea brasiliensis are regulated by phytohormones. The understanding of gene network regulation mechanism of latex formation [...] Read more.

Brassinolide (BR) is an important plant hormone that regulates the growth and development of plants and the formation of yield. The yield and quality of latex from Hevea brasiliensis are regulated by phytohormones. The understanding of gene network regulation mechanism of latex formation in rubber trees is still very limited. In this research, the rubber tree variety CATAS73397 was selected to analyze the relationship between BR, water deficit resistance, and latex yield. The results showed that BR improves the vitality of rubber trees under water deficit by increasing the rate of photosynthesis, reducing the seepage of osmotic regulatory substances, increasing the synthesis of energy substances, and improving the antioxidant system. Furthermore, BR increased the yield and quality of latex by reducing the plugging index and elevating the lutoid bursting index without decreasing mercaptan, sucrose, and inorganic phosphorus. This was confirmed by an increased expression of genes related to latex flow. RNA-seq analysis further indicated that DEG encoded proteins were enriched in the MAPK signaling pathway, plant hormone signal transduction and sucrose metabolism. Phytohormone content displayed significant differences, in that trans-Zeatin, ethylene, salicylic acid, kinetin, and cytokinin were induced by BR, whereas auxin, abscisic acid, and gibberellin were not. In summary, the current research lays a foundation for comprehending the molecular mechanism of latex formation in rubber trees and explores the potential candidate genes involved in natural rubber biosynthesis to provide useful information for further research in relevant areas. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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15 pages, 2135 KiB

Open AccessArticle

Molecular Characterization of Local Walnut (Juglans regia) Genotypes in the North-East Parnon Mountain Region of Greece

by Ioannis Manthos, Thomas Sotiropoulos, Lefkothea Karapetsi, Ioannis Ganopoulos, Emmanouil D. Pratsinakis, Eleni Maloupa and Panagiotis Madesis

Int. J. Mol. Sci. 2023, 24(24), 17230; https://doi.org/10.3390/ijms242417230 - 07 Dec 2023

Viewed by 917

Abstract

Walnut is one of the most important nuts regarding their production and consumption. The available but uncharacterized genetic resources of walnut are important for the development and breeding of local varieties. Greece holds an important number of genetically uncharacterized walnut landraces, especially within [...] Read more.

Walnut is one of the most important nuts regarding their production and consumption. The available but uncharacterized genetic resources of walnut are important for the development and breeding of local varieties. Greece holds an important number of genetically uncharacterized walnut landraces, especially within the area of Parnon, which is considered to play a significant role as an in situ gene bank, due to its unique location traits. However, the genetic characterization and further use of these resources has been insufficient, due to the absence of genetic studies. In this study, we implemented SSR molecular markers, both to genetically characterize the walnut tree genetic diversity of the Parnon area and to identify its unique genetic structure, which will form the starting material for subsequent breeding programs. Overall, high levels of genetic variation were found among the individual walnut accessions that were collected in the Parnon mountain region. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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18 pages, 6000 KiB

Open AccessArticle

Genome-Wide Identification and Characterization of WRKY Transcription Factors in Betula platyphylla Suk. and Their Responses to Abiotic Stresses

by Jiajie Yu, Xiang Zhang, Jiayu Cao, Heming Bai, Ruiqi Wang, Chao Wang, Zhiru Xu, Chunming Li and Guanjun Liu

Int. J. Mol. Sci. 2023, 24(19), 15000; https://doi.org/10.3390/ijms241915000 - 08 Oct 2023

Cited by 3 | Viewed by 997

Abstract

The WRKY transcription factor (TF) family is one the largest plant-specific transcription factor families. It has been proven to play significant roles in multiple plant biological processes, especially stress response. Although many WRKY TFs have been identified in various plant species, WRKYs in [...] Read more.

The WRKY transcription factor (TF) family is one the largest plant-specific transcription factor families. It has been proven to play significant roles in multiple plant biological processes, especially stress response. Although many WRKY TFs have been identified in various plant species, WRKYs in white birch (Betula platyphylla Suk.) remain to be studied. Here, we identified a total of 68 BpWRKYs, which could be classified into four main groups. The basic physiochemical properties of these TFs were analyzed using bioinformatics tools, including molecular weight, isoelectric point, chromosome location, and predicted subcellular localization. Most BpWRKYs were predicted to be located in the nucleus. Synteny analysis found 17 syntenic gene pairs among BpWRKYs and 52 syntenic gene pairs between BpWRKYs and AtWRKYs. The cis-acting elements in the promoters of BpWRKYs could be enriched in multiple plant biological processes, including stress response, hormone response, growth and development, and binding sites. Tissue-specific expression analysis using qRT-PCR showed that most BpWRKYs exhibited highest expression levels in the root. After ABA, salt (NaCl), or cold treatment, different BpWRKYs showed different expression patterns at different treatment times. Furthermore, the results of the Y2H assay proved the interaction between BpWRKY17 and a cold-responsive TF, BpCBF7. By transient expression assay, BpWRKY17 and BpWRKY67 were localized in the nucleus, consistent with the previous prediction. Our study hopes to shed light for research on WRKY TFs and plant stress response. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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Open AccessArticle

Function and Characteristic Analysis of Candidate PEAR Proteins in Populus yunnanensis

by Ping Li, Jing Wang, Derui Jiang, Anmin Yu, Rui Sun and Aizhong Liu

Int. J. Mol. Sci. 2023, 24(17), 13101; https://doi.org/10.3390/ijms241713101 - 23 Aug 2023

Cited by 1 | Viewed by 918

Abstract

PEAR proteins are a type of plant-specific DNA binding with one finger (Dof) transcription factors that play a key role in the regulation of plant growth, especially during phloem cell growth and seed germination in Arabidopsis. However, the identification, characteristics and function [...] Read more.

PEAR proteins are a type of plant-specific DNA binding with one finger (Dof) transcription factors that play a key role in the regulation of plant growth, especially during phloem cell growth and seed germination in Arabidopsis. However, the identification, characteristics and function of PEAR proteins, particularly in woody plants, need to be further studied. In the present study, 43 candidate PEAR proteins harboring the conserved Zf-Dof domain were obtained in Populus yunnanensis. Based on phylogenetic and structural analysis, 10 representative PEAR candidates were selected, belonging to different phylogenetic groups. The functions of PEAR proteins in the stress response, signal transduction, and growth regulation of stem cambium and roots undergoing vigorous cell division in Arabidopsis were revealed based on their expression patterns as characterized by qRT-PCR analysis, in accordance with the results of cis-element analysis. In vitro experiments showed that the interaction of transcription factor (E2F) and cyclin indirectly reflects the growth regulation function of PEAR through light signaling and cell-cycle regulation. Therefore, our results provide new insight into the identity of PEAR proteins and their function in stress resistance and vigorous cell division regulation of tissues in P. yunnanensis, which may serve as a basis for further investigation of the functions and characteristics of PEAR proteins in other plants. Full article

(This article belongs to the Special Issue Advances in Forest Tree Physiology, Breeding and Genetic Research)

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