Brassinosteroids Research Articles

Comprehensive elucidation of the differential physiological kale response to cytokinins under in vitro conditions

BackgroundKale, a versatile cruciferous crop, valued for its pro-health benefits, stress resistance, and potential applications in forage and cosmetics, holds promise for further enhancement of its bioactive compounds through in vitro cultivation methods. Micropropagation techniques use cytokinins (CKs) which are characterized by various proliferative efficiency. Despite the extensive knowledge regarding CKs, there remains a gap in understanding their role in the physiological mechanisms. That is why, here we investigated the effects of three CKs – kinetin (Kin), 6-benzylaminopurine (BAP), and 2-isopentenyladenine (2iP) – on kale physiology, antioxidant status, steroidal metabolism, and membrane integrity under in vitro cultivation.ResultsOur study revealed that while BAP and 2iP stimulated shoot proliferation, they concurrently diminished pigment levels and photosynthetic efficiency. Heightened metabolic activity in response to all CKs was reflected by increased respiratory rate. Despite the differential burst of ROS, the antioxidant properties of kale were associated with the upregulation of guaiacol peroxidase and the scavenging properties of ascorbate rather than glutathione. Notably, CKs fostered the synthesis of sterols, particularly sitosterol, pivotal for cell proliferation and structure of membranes which are strongly disrupted under the action of BAP and 2iP possibly via pathway related to phospholipase D and lipoxygenase which were upregulated. Intriguingly, both CKs treatment spurred the accumulation of sitostenone, known for its ROS scavenging and therapeutic potential. The differential effects of CKs on brassicasterol levels and brassinosteroid (BRs) receptor suggest potential interactions between CKs and BRs.ConclusionBased on the presented results we conclude that the effect evoked by BAP and 2iP in vitro can improve the industrial significance of kale because this treatment makes possible to control proliferation and/or biosynthesis routes of valuable beneficial compounds. Our work offers significant insights into the nuanced effects of CKs on kale physiology and metabolism, illuminating potential avenues for their application in plant biotechnology and medicinal research.

Cotton BOP1 mediates SUMOylation of GhBES1 to regulate fibre development and plant architecture.

The Arabidopsis BLADE-ON-PETIOLE (BOP) genes are primarily known for their roles in regulating leaf and floral patterning. However, the broader functions of BOPs in regulating plant traits remain largely unexplored. In this study, we investigated the role of the Gossypium hirsutum BOP1 gene in the regulation of fibre length and plant height through the brassinosteroid (BR) signalling pathway. Transgenic cotton plants overexpressing GhBOP1 display shorter fibre lengths and reduced plant height compared to the wild type. Conversely, GhBOP1 knockdown led to increased plant height and longer fibre, indicating a connection with phenotypes influenced by the BR pathway. Our genetic evidence supports the notion that GhBOP1 regulates fibre length and plant height in a GhBES1-dependent manner, with GhBES1 being a major transcription factor in the BR signalling pathway. Yeast two-hybrid, luciferase complementation assay and pull-down assay results demonstrated a direct interaction between GhBOP1 and GhSUMO1, potentially forming protein complexes with GhBES1. In vitro and in vivo SUMOylation analyses revealed that GhBOP1 functions in an E3 ligase-like manner to mediate GhBES1 SUMOylation and subsequent degradation. Therefore, our study not only uncovers a novel mechanism of GhBES1 SUMOylation but also provides significant insights into how GhBOP1 regulates fibre length and plant height by controlling GhBES1 accumulation.

Novel Brassinosteroid Analogues with 3,6 Dioxo Function, 24-Nor-22(S)-Hydroxy Side Chain and p-Substituted Benzoate Function at C-23-Synthesis and Evaluation of Plant Growth Effects.

Brassinosteroids (BRs) are an important group of polyhydroxylated naturally occurring steroidal phytohormones found in the plant kingdom in extremely low amounts. Due to the low concentrations in which these compounds are found, much effort has been dedicated to synthesizing these compounds or their structural analogs using natural and abundant sterols. In this work, we report the synthesis of new brassinosteroid analogs obtained from hyodeoxycholic acid, with a 3,6 dioxo function, 24-Nor-22(S)-hydroxy side chain and p-substituted benzoate function at C-23. The plant growth activities of these compounds were evaluated by two different bioassays: rice lamina inclination test (RLIT) and BSI. The results show that BRs' analog with p-Br (compound 41f) in the aromatic ring was the most active at 1 × 10-8 M in the RLIT and BSI assays. These results are discussed in terms of the chemical structure and nature of benzoate substituents at the para position. Electron-withdrawing and size effects seems to be the most important factor in determining activities in the RLIT assay. These results could be useful to propose a new structural requirement for bioactivity in brassinosteroid analogs.

ClBES1/BZR1-1, a brassinosteroid-responsive transcription factor, negatively regulates lignin deposition during secondary xylem formation in Cunninghamia lanceolata

Cunninghamia lanceolata (Chinese fir) is an important industrial coniferous timber tree in southern China with high yield and excellent wood traits. Brassinosteroids (BRs), a class of polyhydroxylated steroidal hormones, play critical roles in the formation of wood, which is the most abundant biomass produced by plants. However, the molecular regulatory network of BR-mediated wood formation remains largely uncharacterized in coniferous trees, especially in Chinese fir. To this end, systematic identification and characterization of the BES1/BZR1 transcription factor (TF), the specific BR-responsive TF, were performed. Seven ClBES1/BZR1 members were screened and distributed on four chromosomes. ClBES1/BZR1s showed various expression profiles in different tissues and growth stages. ClBES1/BZR1–1, a hub gene in BR-mediated xylem development, repressed the transcription activity of ClCCoAOMT and ClMYB3 by directly binding to their promotors. Furthermore, ClBES1/BZR1–1 overexpression significantly decreased the lignin biosynthesis and xylem differentiation compared to wild-type. In contrast, ClBES1/BZR1–1 dominant repression greatly promoted lignin deposition during secondary cell wall (SCW) development. Consequently, by repressing the lignin-related genes’ expression, ClBES1/BZR1–1 negatively regulated the SCW deposition and xylem development in Chinese fir. These findings shed light on the regulatory role of BR modulating lignin accumulation during wood formation.

Genome-wide identification and expression analysis of the BZR gene family in Zanthoxylum armatum DC and functional analysis of ZaBZR1 in drought tolerance.

In this study, six ZaBZRs were identified in Zanthoxylum armatum DC, and all the ZaBZRs were upregulated by abscisic acid (ABA) and drought. Overexpression of ZaBZR1 enhanced the drought tolerance of transgenic Nicotiana benthamian. Brassinosteroids (BRs) are a pivotal class of sterol hormones in plants that play a crucial role in plant growth and development. BZR (brassinazole resistant) is a crucial transcription factor in the signal transduction pathway of BRs. However, the BZR gene family members have not yet been identified in Zanthoxylum armatum DC. In this study, six members of the ZaBZR family were identified by bioinformatic methods. All six ZaBZRs exhibited multiple phosphorylation sites. Phylogenetic and collinearity analyses revealed a closest relationship between ZaBZRs and ZbBZRs located on the B subgenomes. Expression analysis revealed tissue-specific expression patterns of ZaBZRs in Z. armatum, and their promoter regions contained cis-acting elements associated with hormone response and stress induction. Additionally, all six ZaBZRs showed upregulation upon treatment after abscisic acid (ABA) and polyethylene glycol (PEG), indicating their participation in drought response. Subsequently, we conducted an extensive investigation of ZaBZR1. ZaBZR1 showed the highest expression in the root, followed by the stem and terminal bud. Subcellular localization analysis revealed that ZaBZR1 is present in the cytoplasm and nucleus. Overexpression of ZaBZR1 in transgenic Nicotiana benthamiana improved seed germination rate and root growth under drought conditions, reducing water loss rates compared to wild-type plants. Furthermore, ZaBZR1 increased proline content (PRO) and decreased malondialdehyde content (MDA), indicating improved tolerance to drought-induced oxidative stress. The transgenic plants also showed a reduced accumulation of reactive oxygen species. Importantly, ZaBZR1 up-regulated the expression of drought-related genes such as NbP5CS1, NbDREB2A, and NbWRKY44. These findings highlight the potential of ZaBZR1 as a candidate gene for enhancing drought resistance in transgenic N. benthamiana and provide insight into the function of ZaBZRs in Z. armatum.

Identification of host gene regulation and resistance pathway dynamics at diverse infection stages of Rhizoctonia solani AG3-TB.

Rhizoctonia solani is a fungal pathogen that causes significant losses in agricultural production. Because of its rapid transmission and broad host range, the exploration of genes involved in defense responses to the infection of R. solani has become an important task. Here, we performed a time-course RNA-Seq experiment to explore crucial genes or pathways involved in host responses to R. solani AG3-TB infection at 6, 12, 24, 36, 48, and 72 hours post inoculation (hpi). GO and KEGG enrichment analysis revealed that most DEGs were enriched in the basal metabolism pathways, including carbohydrate metabolic processes and the biosynthesis of amino acids. Moreover, catalase (CAT) and superoxide dismutase (SOD) were up-regulated, and transcription factors (TFs) such as WRKY, AP2, and MYB were increased significantly compared to the control (0 hpi). Silencing of WRKY70 and catalase-3 exhibited elevated susceptibility to the fungal infection. To summarize, the TFs WRKY70 and WRKY75, genes involved in jasmonic acid (JA), salicylic acid (SA), and brassinosteroids (BR) signaling pathways, and defense-related enzymes may play crucial roles in the host responses to R. solani AG3-TB infection.

ZmD11 Gene Regulates Tobacco Plant Floral Development under Drought Stress

Maize is most sensitive to drought stress at the floral stage by reducing tassel and silk quality, and thus improving drought tolerance at this stage may help preserve yield. It has been reported that BRs (brassinosteroids) promote floral development under drought stress. However, the function of the brassinosteroid biosynthesis gene ZmDWARF11 (ZmD11) on floral growth under drought stress has not been elucidated. This study found that under normal growth conditions, the heterologous over-expression of ZmD11 significantly enhanced both the vegetative growth and floral development of tobacco. Under drought stress, overexpressing ZmD11 reduced stress-induced tobacco flower size reduction, while it did not affect vegetative growth. After drought treatment, the activities of protective enzymes, including CAT (Catalase), SOD (Superoxide Dismutase), and POD (Peroxidase), were higher, while the content of MDA (Malondialdehyde) was lower in ZmD11 over-expression tobacco lines than that in the wild type control. The relative expression of dehydrin-related genes NtLeat5 and NtERD10 was increased in ZmD11 over-expression tobacco lines compared to that in the control. In summary, we reported that ZmD11 plays a role in tobacco floral development under drought stress. Our data are valuable in understanding the functions of BRs in regulating plant floral development under drought stress.

Physiological Mechanisms of BvCPD Regulation in Sugar Beet Growth

Sugar beet is an important sugar crop, and its roots are mainly used for processing raw materials to produce products such as sugar, molasses, and saccharin, as well as being used as fodder for livestock. BvCPD, a key enzyme gene for brassinosteroid (BR) synthesis, regulates the development of parenchyma cells and vascular bundles by promoting BR synthesis, which promotes the expansion of the sugar beet taproot and influences the growth, development, and yield of sugar beets. This study investigated the impact of BvCPD on the physiological metabolism of sugar beet utilizing BvCPD overexpression, silent, and wild-type (WT) lines. BvCPD increased the chlorophyll content and maximum photochemical efficiency and improved the photosynthetic characteristics of sugar beet leaves. Simultaneously, BvCPD increased the rate of sugar beet taproot respiration and ATP content by enhancing the activities of phosphoglycerate kinase, alcohol dehydrogenase, sucrose synthase, and sucrose synthase catabolism. Moreover, BvCPD induced changes in the sugar fraction content, which increased the sugar yield of a single plant. In addition, BvCPD promoted water absorption, nitrogen accumulation, and lignin/cellulose synthesis activities, facilitated by increased activities of phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, cellulose synthase, and protein serine/threonine phosphatases, providing the requisite energy and materials for sugar beet growth. These findings not only provide a new perspective for understanding the physiological mechanisms regulating the growth of sugar beets but also provide a theoretical basis for the future improvement of sugar beet varieties through molecular breeding techniques.

24-epibrassinolide as a multidimensional regulator of rice (Oryza sativa) physiological and molecular responses under isoproturon stress

Brassinosteroids (BRs) can regulate various processes in plant development and defense against environmental stress. In this study, the contribution of BRs in the degradation of isoproturon (IPU) in rice has been established. IPU has a significant effect on rice growth, chlorophyll content, and membrane permeability. When treated with 1.0 μmol/L 24-epibrassinolide (EBR), a BR analogue, the associated symptoms of rice poisoning were alleviated as the IPU levels in the rice and growth media were decreased. In the presence of EBR, the activities of several IPU-related detoxification enzymes were enhanced to cope with the stress due to IPU. An RNA-sequencing (RNA-Seq) has been performed to determine the variation of transcriptomes and metabolic mechanisms in rice treated with EBR, IPU, or IPU+EBR. Some of the differentially expressed genes (DEGs) were Phase I-III reaction components of plants, such as cytochrome P450 (CYP450), glutathione S-transferase (GST), glycosyltransferases (GTs), and the ATP-binding cassette transporter (ABC transporter). The expression of some signal transduction genes was significantly up-regulated. The relative content of low-toxicity IPU metabolites increased due to the presence of EBR as determined by UPLC/Q-TOF-MS/MS. The IPU metabolic pathways include enzyme-catalyzed demethylation, hydroxylation, hydrolysis, glycosylation, and amino acid conjugation processes. The results suggest that EBR plays a key role in the degradation and detoxification of IPU. This study has provided evidence that BRs regulate the metabolism and detoxification of IPU in rice, and offers a new approach to ensuring cleaner crops by eliminating pesticide residues in the environment.

OsFK1 encodes C-14 sterol reductase, which is involved in sterol biosynthesis and affects premature aging of leaves in rice

The enzyme C-14 sterol reductase is involved in biosynthesis of brassinosteroids (BR) and sterols, as well as plant development. OsFK1, a member of the sterol biosynthesis pathway located in the endoplasmic reticulum (ER), encodes C-14 sterol reductase. However, there is little research on the function of C-14 sterol reductase in rice. Compared with the wild type, an osfk1 mutant showed dwarf phenotype and premature aging in the second leaf during the trefoil stage, and abnormal development of leaf veins during the tillering stage. The osfk1 mutant showed signs of aberrant PCD, as evidenced by TUNEL staining. This suggested that high ROS buildup caused DNA damage and ROS-mediated cell death in the mutant. The osfk1 mutant also showed decreased chlorophyll content and aberrant chloroplast structure. Sequencing of the osfk1 mutant allele revealed a non-synonymous G to A mutation in the final intron, leading to early termination. Here, we identified the OsFK1 allele, cloned it by Mutmap sequencing, and verified it by complementation. HPLC-MS/MS assays demonstrated that the osfk1 mutation caused lower phytosterol levels. These findings showed that the OsFK1 allele encoding C-14 sterol reductase is involved in phytosterol biosynthesis and mediates normal development of rice plants.

Interaction of the Transcription Factors BES1/BZR1 in Plant Growth and Stress Response.

Bri1-EMS Suppressor 1 (BES1) and Brassinazole Resistant 1 (BZR1) are two key transcription factors in the brassinosteroid (BR) signaling pathway, serving as crucial integrators that connect various signaling pathways in plants. Extensive genetic and biochemical studies have revealed that BES1 and BZR1, along with other protein factors, form a complex interaction network that governs plant growth, development, and stress tolerance. Among the interactome of BES1 and BZR1, several proteins involved in posttranslational modifications play a key role in modifying the stability, abundance, and transcriptional activity of BES1 and BZR1. This review specifically focuses on the functions and regulatory mechanisms of BES1 and BZR1 protein interactors that are not involved in the posttranslational modifications but are crucial in specific growth and development stages and stress responses. By highlighting the significance of the BZR1 and BES1 interactome, this review sheds light on how it optimizes plant growth, development, and stress responses.

Post-translational Regulation of BRI1-EMS Suppressor 1 and Brassinazole-resistant 1.

BRI1-EMS Suppressor 1 (BES1) and Brassinazole resistant 1 (BZR1) are two highly similar master transcription factors of the brassinosteroid (BR) signaling pathway that regulate a variety of plant growth and development processes as well as stress responses. Previous genetic and biochemical analyses have established a complex regulatory network to control the two transcription factors. This network includes coordination with other transcription factors and interactors, multiple post-translational modifications (PTMs), and differential subcellular localizations. In this review, we systematically detail the functions and regulatory mechanisms of various PTMs: phosphorylation/dephosphorylation, ubiquitination/deubiquitination, SUMOylation/deSUMOylation, oxidation/reduction, in regulating the subcellular localization, protein stability, and the transcriptional activity of BES1/BZR1. We also discuss the current knowledge about the BES1/BZR1-interactors mediating the dynamic nucleocytoplasmic shuttling of BES1 and BZR1.

Xylooligosaccharides Enhance Lettuce Root Morphogenesis and Growth Dynamics.

Enhancing root development is pivotal for boosting crop yield and augmenting stress resilience. In this study, we explored the regulatory effects of xylooligosaccharides (XOSs) on lettuce root growth, comparing their impact with that of indole-3-butyric acid potassium salt (IBAP). Treatment with XOS led to a substantial increase in root dry weight (30.77%), total root length (29.40%), volume (21.58%), and surface area (25.44%) compared to the water-treated control. These enhancements were on par with those induced by IBAP. Comprehensive phytohormone profiling disclosed marked increases in indole-3-acetic acid (IAA), zeatin riboside (ZR), methyl jasmonate (JA-ME), and brassinosteroids (BRs) following XOS application. Through RNA sequencing, we identified 3807 differentially expressed genes (DEGs) in the roots of XOS-treated plants, which were significantly enriched in pathways associated with manganese ion homeostasis, microtubule motor activity, and carbohydrate metabolism. Intriguingly, approximately 62.7% of the DEGs responsive to XOS also responded to IBAP, underscoring common regulatory mechanisms. However, XOS uniquely influenced genes related to cutin, suberine, and wax biosynthesis, as well as plant hormone signal transduction, hinting at novel mechanisms of stress tolerance. Prominent up-regulation of genes encoding beta-glucosidase and beta-fructofuranosidase highlights enhanced carbohydrate metabolism as a key driver of XOS-induced root enhancement. Collectively, these results position XOS as a promising, sustainable option for agricultural biostimulation.

Heavy metal toxicity induced by sewage water treatment in three different vegetables (lettuce, spinach and cabbage) was alleviated by brassinosteroid and silicon supplementation

Purpose: Heavy metal stress due to the application of sewage water is considered a leading factor for constrained plant growth. Therefore, Current study was performed in the field to investigate the interactive influence of two irrigation sources (canal and sewage) and exogenous application of brassinosteroid (BRs) and silicon (Si) at different rates on growth, photosynthetic and physiological attributes of three leafy vegetables (lettuce, cabbage, and spinach). Methods: Three treatments were applied such as control, BRs and Si with three replications under split plot factorial design. Results: The results indicated that all the growth parameters including fresh biomass of plants and roots, dry biomass of plant and root, leaf area (LA), photosynthetic traits, chlorophyll contents, water use efficiency (WUE), activity of antioxidant enzymes; superoxide dismutase (SOD), peroxidase (POD), Catalase (CAT), ascorbate peroxidase (APX) and uptake of silicon except Cd and Pb contents were improved significantly with the foliar spray of BRs and Si over control treatment under both types of irrigation sources. However maximum improvement in leafy vegetables was recorded when the foliar spray of BRs and Si were applied under canal water irrigation. Conclusions: The foliar application of BRs and Si was proved as an ameliorating strategy for improving tolerance mechanisms associated with heavy metal stress. The major restoring mechanism was the restricted translocation of Cd and Pb leading to better growth and physiology under sewage water. Thus the application of BRs and Si reduced the detrimental effect of Cd and Pb led to improve the growth and physiological traits of leafy vegetables under irrigation with sewage water.

The lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branch number by affecting brassinosteroid biosynthesis.

Branch number is one of the most important agronomic traits of fruit trees such as peach. Little is known about how LncRNA and/or miRNA modules regulate branching through transcription factors. Here, we used molecular and genetic tools to clarify the molecular mechanisms underlying brassinosteroid (BR) altering plant branching. We found that the number of sylleptic branch and BR content in pillar peach ('Zhaoshouhong') was lower than those of standard type ('Okubo'), and exogenous BR application could significantly promote branching. PpTCP4 expressed great differentially comparing 'Zhaoshouhong' with 'Okubo'. PpTCP4 could directly bind to DWARF2 (PpD2) and inhibited its expression. PpD2 was the only one differentially expressed key gene in the path of BR biosynthesis. At the same time, PpTCP4 was identified as a target of miR6288b-3p. LncRNA1 could act as the endogenous target mimic of miR6288b-3p and repress expression of miR6288b-3p. Three deletions and five SNP sites of lncRNA1 promoter were found in 'Zhaoshouhong', which was an important cause of different mRNA level of PpTCP4 and BR content. Moreover, overexpressed PpTCP4 significantly inhibited branching. A novel mechanism in which the lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branching number was proposed.

Transcriptome analysis unravels differential genes involved in essential oil content in callus and tissue culture seedlings of Lavandula angustifolia

Lavender (Lavandula angustifolia Mill.) essential oil is of high medicinal and economic importance. The preliminary results of this study found that lavender tissue culture seedlings contained 2.1% essential oil, which was 21 times that of callus tissue. However, the mechanisms involved in its synthesis are unclear. This study used transcriptome sequencing of L. angustifolia callus and tissue culture seedlings to compare changes in differentially expressed genes (DEGs) and metabolic pathways. Transcriptome analysis revealed 2394 DEGs in callus and tissue culture seedlings. Several DEGs were enriched in plant hormone signal transduction, as well as the biosynthesis of terpenoids and other secondary metabolites. In the terpenoid biosynthesis pathway, 93 genes were differentially expressed, and four receptors protein genes (BRI1) of brassinosteroid (BR) hormone were significantly differentially expressed. This study provides deeper insights into regulatory genes involved in terpenoid biosynthesis and BR signal transduction in L. angustifolia, contributing to the genetic improvement of L. angustifolia.

The Role of Environmental Factors and Plant Growth Regulators on Grapes Coloration

Grapevine is the world's commercial horticulture crop. Poor coloration of grapes is one of the problems in grape production. Climate changes could negatively affect grape quality by reducing color formation. The effect of high temperatures on anthocyanin content and composition in the main red-producing grapes would help estimate their phenotypic change and perhaps predict whether they will be able to sustain the attributes of high-quality grapes in the context of climate change. Climate changes played an important role in lack sufficient berry color especially high temperature inhibited L-phenylalanineammonialyase (PAL). L-phenylalanineammonialyase improved accumulation of anthocyanin in the skin of grape berries. Environmental factors like light, temperature and irrigation are effective in either grapes coloration or discoloration. Plant growth regulators like Brassinosteroids (BRs), Jasmonic acid (JA), Salicylic acid (SA) and Abscisic acid (ABA) are accelerating the accumulation of anthocyanin in grapes berry skin. So it is very important to know how grapes coloration, the effect of plant growth regulators and environmental factors on grapes coloration.

Transcriptome and widely metabolomic analysis reveal hormones and sugar signaling pathways contribute to the normal growth of seeds in young Picea neoveitchii Mast. trees

Abnormal seed growth is a problem in Picea neoveitchii Mast. in China that threatens the existence of this evergreen coniferous tree. However, the degree of abnormal seed growth varies in different age groups; regrettably, the causes behind abnormal seed growth at different ages are totally unclear. Thus, we compared the seeds of two ages: Gansu (GS) province, a 50-year-old tree (GS50), and a 300-year-old tree (GS300). Results indicated that 22187 unigenes were commonly found in both groups, whereas 5328 and 6079 unigenes were uniquely found in GS50 and GS300, respectively. Furthermore, a total of 5129 differentially expressed unigenes were identified between GS50 and GS300, with 2431 upregulated and 2698 downregulated. On the basis of Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, plant hormone signal transduction and starch and sucrose metabolism pathways were further selected for their potential involvement in seed growth at both ages. A wide-targeted metabolomics-based approach using liquid chromatography mass spectrometry (LC-MS) was applied to study the difference between GS50 and GS300. The results showed that there were 35 different metabolites in total being detected, mainly amino acids and sugars. Subsequently, GS50 revealed the highest number of normal seeds and the lowest number of abnormal seeds in comparison with GS300 by improving endogenous indole-3-acetic acid (IAA), zeatin riboside (ZR), and gibberellic acid 3 (GA3) contents and reducing methyl jasmonate (JA-me), abscisic acid (ABA), and brassinosteroid (BR) contents. Our research provides important evidence on the growth of seeds in different age groups of trees that might help improve seed growth in old trees.

A multifaceted crosstalk between brassinosteroid and gibberellin regulates the resistance of cucumber to Phytophthora melonis.

Cucumber plants are highly susceptible to the hemibiotroph oomycete Phytophthora melonis. However, the mechanism of resistance to cucumber blight remains poorly understood. Here, we demonstrated that cucumber plants with impairment in the biosynthesis of brassinosteroids (BRs) or gibberellins (GAs) were more susceptible to P. melonis. By contrast, increasing levels of endogenous BRs or exogenously application of 24-epibrassinolide enhanced the resistance of cucumber plants against P. melonis. Furthermore, we found that both knockout and overexpression of the BR biosynthesis gene CYP85A1 reduced the endogenous GA3 content compared with that of wild-type plants under the condition of inoculation with P. melonis, and the enhancement of disease resistance conferred by BR was inhibited in plants with silencing of the GA biosynthetic gene GA20ox1 or KAO. Together, these findings suggest that GA homeostasis is an essential factor mediating BRs-induced disease resistance. Moreover, BZR6, a key regulator of BR signaling, was found to physically interact with GA20ox1, thereby suppressing its transcription. Silencing of BZR6 promoted endogenous GA biosynthesis and compromised GA-mediated resistance. These findings reveal multifaceted crosstalk between BR and GA in response to pathogen infection, which can provide a new approach for genetically controlling P. melonis damage in cucumber production.

Genetic and Molecular Regulation of Cotton Fiber Initiation and Elongation

Cotton fiber, a crucial and sustainable resource for global textile production, undergoes a complex five-stage developmental process, encompassing initiation, elongation, transition, secondary cell wall biosynthesis, and maturation. These elongated single-cell fibers originate from the outer ovule epidermis. The development of cotton fibers involves intricate changes in gene expression and physiological processes, resulting in a nearly pure cellulose product that is vital for the global cotton industry. Decoding the genes associated with fiber development enhances our understanding of cotton fiber mechanisms and facilitates the cultivation of varieties with enhanced quality. In recent decades, advanced omics approaches, including genomics, transcriptomics, and proteomics, have played a pivotal role in identifying the genes and gene products linked to cotton fiber development, including the MYB transcription factor family, which coordinates cotton fiber development. Molecular studies have revealed the transcription factors, like MYB, WRKY, Homeodomain Leucine Zipper (HD-ZIP), and basic helix–loop–helix (bHLH), influencing fiber initiation and elongation. The intricate interplay of phytohormones, like auxin, gibberellic acid (GA), brassinosteroids (BRs), jasmonic acid (JA), ethylene, abscisic acid (ABA), and cytokinin, is explored, providing a comprehensive perspective on the shaping of cotton fibers. Numerous candidate genes and cellular processes affecting various aspects of fiber development hold promise for genetic engineering or marker-assisted breeding to improve fiber quality. This review presents a comprehensive overview of key achievements in cotton molecular biology, with a specific emphasis on recent advancements in understanding the transcription factors and phytohormones involved in cotton fiber initiation and elongation.