Brassinosteroid Signaling Pathway Research Articles

Integrative analysis of the transcriptome, targeted metabolome, and anatomical observation provides insights into the brassinosteroids-mediated seasonal variation of cambial activity in Chinese fir

Chinese fir (Cunninghamia lanceolata) is widely planted in southern China due to its strong adaptability and fast-growing. Wood formation is derived from the periodic changes of cambial activity that is regulated by environmental cues and phytohormone signals. Brassinosteroids (BRs), a class of plant-specific steroid hormones, play central roles in modulating cambial activity and xylem development. To decipher the regulatory role of BR in the dynamic change of Chinese fir cambium, a comprehensive analysis of the transcriptome, targeted metabolome, and anatomical observation was conducted. The application of 24-epibrassinolide (EBR, 10 μM) significantly increased the cambial cell layers, resulting in the thickening of the secondary xylem. Conversely, brassinazole (Brz) treatment strikingly inhibited the xylem development by attenuating cambial activity. Moreover, 1583 up-regulated differentially expressed genes (DEGs) were shared in stages A (reactivating), C (active), and E (dormant), which were annotated into the xylem formation and BR signaling pathway. Metabolomic profiling of phytohormone indicated that the contents of brassinolide (BL, the most active BR), castasterone (CS), and typhasterol (TY) were distinctly increased in stage C. Furthermore, ClBES1/BZR1, a hub gene in the co-expression network, dramatically activated the expression of ClPAL2 and ClMYB4 by binding to their promotors. Collectively, these results elucidate the potential role of BR in dynamic changes in the cambial zone and provide insight into the regulatory mechanism of wood formation in conifers.

Integration of mRNA-miRNA Reveals the Possible Role of PyCYCD3 in Increasing Branches Through Bud-Notching in Pear (Pyrus bretschneideri Rehd.).

Bud-notching in pear varieties with weak-branches enhances branch development, hormone distribution, and germination, promoting healthier growth and improving early yield. To examine the regulatory mechanisms of endogenous hormones on lateral bud germination in Pyrus spp. (cv. 'Huangguan') (Pyrus bretschneideri Rehd.), juvenile buds were collected from 2-year-old pear trees. Then, a comprehensive study, including assessments of endogenous hormones, germination and branching rates, RNA-seq analysis, and gene function analysis in these lateral buds was conducted. The results showed that there was no significant difference in germination rate between the control and bud-notching pear trees, but the long branch rate was significantly increased in bud-notching pear trees compared to the control (p < 0.05). After bud-notching, there was a remarkable increase in IAA and BR levels in the pruned section of shoots, specifically by 141% and 93%, respectively. However, the content of ABA in the lateral buds after bud-notching was not significantly different from the control. Based on RNA-seq analysis, a notable proportion of the differentially expressed genes (DEGs) were linked to the plant hormone signal transduction pathway. Notably, the brassinosteroid signaling pathway seemed to have the closest connection with the branching ability of pear with the related genes encoding BRI1 and CYCD3, which showed significant differences between lateral buds. Finally, the heterologous expression of PyCYCD3 has a positive regulatory effect on the increased Arabidopsis growth and branching numbers. Therefore, the PyCYCD3 was identified as an up-regulated gene that is induced via brassinosteroid (BR) and could act as a conduit, transforming bud-notching cues into proliferative signals, thereby governing lateral branching mechanisms in pear trees.

CNGC20 plays dual roles in regulating plant growth and immunity in Brassica napus

Inflorescence architecture is determined by inflorescence length, branch angles and the density of siliques, which affects planting density, lodging resistance and mechanical operation in rapeseed. However, the molecular mechanisms controlling inflorescence architecture are poorly understood, restricting the progress of breeding varieties with ideal plant architecture in oilseed rape. In this study, we have identified and characterized a rapeseed inflorescence development mutant, reduced inflorescence length (ril), which exhibits determinate and shortened inflorescences, reduced plant height, compact branches, and increased silique density. Through BSA-seq and map-based cloning, we find that RIL encodes a cyclic nucleotide-gated channel 20 (BnaA01.CNGC20). A substitution of proline at the 304th position to leucine (P304L) was identified in the conserved transmembrane domain of BnaA01.CNGC20. This P304L substitution neither affects the subcellular localization and self-assembly of BnaA01.CNGC20, nor disrupts the interactions with BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1), which interacts with CNGC20 and phosphorylates it to regulate Ca2+ channel stability. However, the P304L substitution increases channel activity and Ca2+ influx, which in turn induces immune responses such as cell death, H2O2 accumulation, upregulation of pathogenesis-related genes, and pattern-triggered immunity. The enhanced immunity improves the resistance to Leptosphaeria biglobosa and Sclerotinia sclerotiorum. Transcriptome analysis further revealed that CNGC20 plays dual roles in regulating plant growth and immunity via the brassinosteroid and auxin signaling pathways. The findings in this study provide deeper insights into the intricate relationship between cytosolic Ca2+ level and plant development and immunity, as well as the trade-off between immunity and the performance of yield-related traits in the heterozygous plants (+/ril), which may serve as a guide for balancing yield and disease resistance in oilseed rape breeding.

Identification of the BZR Family in Garlic (Allium sativum L.) and Verification of the AsBZR11 under Salt Stress

Brassinazole-Resistant (BZR) is an important transcription factor (TF) in the brassinosteroid (BR) signaling pathway, which plays a crucial role in plant growth, development and stress resistance. In this study, we performed a genome-wide analysis of BZRs in garlic (Allium sativum L.) and identified a total of 11 members of the AsBZR gene family. By comparing the expression patterns of AsBZR genes under salt stress, the candidate gene AsBZR11 with salt tolerance function was identified. Subcellular localization results showed that AsBZR11 was localized in the nucleus. The salt tolerance of overexpression lines improved, and the germination rate and root length of overexpression lines increased as compared with wild type. The content of reactive oxygen species (ROS) decreased, and the activity of antioxidant enzymes increased in AsBZR11-OE, suggesting that AsBZR11 has the function of improving plant salt tolerance. Our results enriched the knowledge of plant BZR family and laid a foundation for the molecular mechanism of salt tolerance of garlic, which will provide a theoretical basis for the subsequent creation of salt-tolerant germplasm resources.

Synergistic interaction between brassinosteroid and jasmonate pathways in rice response to cadmium toxicity

Brassinosteroids (BRs) and jasmonic acid (JA) are known to be involved in regulating plant responses to cadmium (Cd) stress. However, their specific roles and interaction in this process remain unclear. In this study, we discovered that exogenous BR alleviated Cd-mediated growth inhibition of rice seedlings. Enhanced Cd tolerance was also observed in m107, a BR-overproduction mutant. Phenotypic analysis of genetic materials involved in BR signaling confirmed the positive role of BR in regulating rice response to Cd toxicity. OsDLT, a key component in the BR signaling pathway, was found to be crucial for BR-mediated Cd tolerance. Further analysis demonstrated that activation of the BR pathway reduced the accumulation of Cd and reactive oxygen species (ROS) by modulating the expression of genes associated with Cd transport and ROS scavenging. Interestingly, transcriptome analysis indicated that the JA pathway was enriched in OsDLT-regulated differently expressed genes (DEGs). Gene expression and hormone assays showed that BR promoted the expression of JA pathway genes and JA levels in plants. Moreover, BR-induced tolerance was compromised in the JA signaling-deficient mutant osmyc2, suggesting that BR-mediated Cd resistance depends on the activation of the JA signaling pathway. Overall, our study revealed the synergistic interaction between BR and JA pathways in rice response to Cd stress, providing insights into the complex hormonal interplay in plant tolerance to heavy metals.

Phosphorylation of the transcription factor SlBIML1 by SlBIN2 kinases delays flowering in tomato.

Brassinosteroids (BRs) are well known for their important role in the regulation of plant growth and development. Plants with deficiency in BR signaling show delayed plant development and exhibit late flowering phenotypes. However, the precise mechanisms involved in this process require investigation. In this study, we cloned homologs of BRASSINOSTEROID INSENSITIVE 2 (SlBIN2), the GSK3-like protein kinase in tomato (Solanum lycopersicum). We characterized growth-related processes and phenotypic changes in the transgenic lines and found that SlBIN2s transgenic lines have delayed development and slow growing phenotypes. SlBIN2s work redundantly to negatively regulate BR signaling in tomato. Furthermore, the transcription factor SlBIN2.1-INTERACTING MYB-LIKE 1 (SlBIML1) was identified as a downstream substrate of SlBIN2s that SlBIN2s interact with and phosphorylate to synergistically regulate tomato developmental processes. Specifically, SlBIN2s modulated protein stability of SlBIML1 by phosphorylating multiple amino acid residues, including the sites Thr266 and Thr280. This study reveals a branch of the BR signaling pathway that regulates the vegetative growth phase and delays floral transition in tomato without the feedback affecting BR signaling. This information enriches our understanding of the downstream transduction pathway of BR signaling and provides potential targets for adjusting tomato flowering time.

The brassinosteroid receptor StBRI1 promotes tuber development by enhancing plasma membrane H+-ATPase activity in potato.

The brassinosteroid (BR) receptor BRASSINOSTEROID-INSENSITIVE 1 (BRI1) plays a critical role in plant growth and development. Although much is known about how BR signaling regulates growth and development in many crop species, the role of StBRI1 in regulating potato (Solanum tuberosum) tuber development is not well understood. To address this question, a series of comprehensive genetic and biochemical methods were applied in this investigation. It was determined that StBRI1 and Solanum tuberosum PLASMA MEMBRANE (PM) PROTON ATPASE2 (PHA2), a PM-localized proton ATPase, play important roles in potato tuber development. The individual overexpression of StBRI1 and PHA2 led to a 22% and 25% increase in tuber yield per plant, respectively. Consistent with the genetic evidence, in vivo interaction analysis using double transgenic lines and PM H+-ATPase activity assays indicated that StBRI1 interacts with the C-terminus of PHA2, which restrains the intramolecular interaction of the PHA2 C-terminus with the PHA2 central loop to attenuate autoinhibition of PM H+-ATPase activity, resulting in increased PHA2 activity. Furthermore, the extent of PM H+-ATPase autoinhibition involving phosphorylation-dependent mechanisms corresponds to phosphorylation of the penultimate Thr residue (Thr-951) in PHA2. These results suggest that StBRI1 phosphorylates PHA2 and enhances its activity, which subsequently promotes tuber development. Altogether, our results uncover a BR-StBRI1-PHA2 module that regulates tuber development and suggest a prospective strategy for improving tuberous crop growth and increasing yield via the cell surface-based BR signaling pathway.

WITHDRAWN: Grape defense against gray mold involves VvBZR1-mediated autophagy

Brassinosteroids (BRs) are a class of polyhydroxylated steroidal phytohormones that effectively affect the disease resistance in grape. However, the molecular mechanism of BR signaling networks responsible for activation of host defense against gray mold infection remained to be elucidated. The induced resistance mechanism of eBR treatment on table grapes (Vitis vinifera L. cv. Thompson Seedless) was conducted by an artificial inoculation trial. Grape berries were soaked in 0.5 mg L-1 24-epibrassinolide solution, and Botrytis cinerea suspension was injected after 6 hours. We reported a novel defense mechanism that BR-regulated autophagy in grape berry against B. cinerea. Exogenous application of 24-epibrassinolide (eBR) enhanced the grape disease resistance. The eBR-treated berries activated an oxidation-reduction (redox), polyamines metabolism, and autophagy during Botrytis infection. Transcript of BR signaling pathway genes were up-regulated within 12 h. In addition, transcriptome analysis in EBR-treated grapes infected with gray mold showed that the differentially expressed genes (DEGs) were enriched in the metabolic pathway of BR signaling pathway and autophagy. Meanwhile, the endogenous BR, SA and JA accumulated transiently. Overexpressing and silencing VvBZR1 in grape significantly affected oxidation, autophagy, and defense response. DNA affinity purification sequencing (Dap-seq), Yeast one-hybrid assay (Y1H) and dual luciferase assays (LUC) verified VvBZR1 transcriptionally regulated the autophagy related gene VvATG18a. Overexpressing VvATG18a improved the resistance of grapes to gray mold. Overall, this study sheds light on the immune mechanisms underlying the involvement of the BR signal transduction pathway in grape innate immunity, highlighting the pivotal role of VvBZR1-mediated autophagy in enhancing disease resistance.

Global Characterization of DNA Methylation during Rice Leaf Angle Development.

During plant development and growth, genomic DNA accumulates chemical markers that determine the levels of gene expression. DNA methylation is an important epigenetic marker involved in plant developmental events. However, the characterization of the role of DNA methylation in rice leaf angle development has lagged behind. Herein, we performed bisulfite sequencing to characterize DNA methylation sites and performed transcriptome and small RNA sequencing during leaf angle development. The results revealed a global reduction in CG methylation during leaf angle establishment. A reduction in gene body CG methylation appears to play a vital role in leaf angle development. The hypomethylated and weakly expressed genes were functionally enriched in the brassinosteroid and auxin signaling pathways. Additionally, the main DNA methyltransferases were inactive. The addition of exogenous DNA methylation inhibitor 5-azacytidine increased the leaf angle, which confirmed that DNA methylation is crucial for leaf angle development. This study revealed a gradual decrease in 24-nucleotide siRNA levels during leaf angle development, particularly in relation to the enrichment of 24-nucleotide siRNAs at different hypomethylated regions that induce leaf angle inclination. Our results indicate crucial roles for DNA methylation in the rice leaf angle developmental stages.

PmLBD3 links auxin and brassinosteroid signalling pathways on dwarfism in Prunus mume

BackgroundGrafting with dwarf rootstock is an efficient method to control plant height in fruit production. However, the molecular mechanism remains unclear. Our previous study showed that plants with Prunus mume (mume) rootstock exhibited a considerable reduction in plant height, internode length, and number of nodes compared with Prunus persica (peach) rootstock. The present study aimed to investigate the mechanism behind the regulation of plant height by mume rootstocks through transcriptomic and metabolomic analyses with two grafting combinations, ‘Longyan/Mume’ and ‘Longyan/Peach’.ResultsThere was a significant decrease in brassinolide levels in plants that were grafted onto mume rootstocks. Plant hormone signal transduction and brassinolide production metabolism gene expression also changed significantly. Flavonoid levels, amino acid and fatty acid metabolites, and energy metabolism in dwarf plants decreased. There was a notable upregulation of PmLBD3 gene expression in plant specimens that were subjected to grafting onto mume rootstocks. Auxin signalling cues promoted PmARF3 transcription, which directly controlled this upregulation. Through its binding to PmBAS1 and PmSAUR36a gene promoters, PmLBD3 promoted endogenous brassinolide inactivation and inhibited cell proliferation.ConclusionsAuxin signalling and brassinolide levels are linked by PmLBD3. Our findings showed that PmLBD3 is a key transcription factor that regulates the balance of hormones through the auxin and brassinolide signalling pathways and causes dwarf plants in stone fruits.

GhEXL3 participates in brassinosteroids regulation of fiber elongation in Gossypium hirsutum.

Cotton fiber (Gossypium hirsutum) serves as an ideal model for investigating the molecular mechanisms of plant cell elongation at the single-cell level. Brassinosteroids (BRs) play a crucial role in regulating plant growth and development. However, the mechanism by which BR influences cotton fiber elongation remains incompletely understood. In this study, we identified EXORDIUM-like (GhEXL3) through transcriptome analysis of fibers from BR-deficient cotton mutant pagoda 1 (pag1) and BRI1-EMS-SUPPRESSOR 1 (GhBES1.4, encoding a central transcription factor of BR signaling) overexpression cotton lines. Knockout of GhEXL3 using CRISPR/Cas9 was found to impede cotton fiber elongation, while its overexpression promoted fiber elongation, suggesting a positive regulatory function for GhEXL3 in fiber elongation. Furthermore, in vitro ovule culture experiments revealed that the overexpression of GhEXL3 partially counteracted the inhibitory effects of brassinazole (BRZ) on cotton fiber elongation, providing additional evidence of GhEXL3 involvement in BR signaling pathways. Moreover, our findings demonstrate that GhBES1.4 directly binds to the E-box (CACGTG) motif in the GhEXL3 promoter region and enhances its transcription. RNA-seq analysis revealed that overexpression of GhEXL3 upregulated the expression of EXPs, XTHs, and other genes associated with fiber cell elongation. Overall, our study contributes to understanding the mechanism by which BR regulates the elongation of cotton fibers through the direct modulation of GhEXL3 expression by GhBES1.4.

The cap-binding complex modulates ABA-responsive transcript splicing during germination in barley (Hordeum vulgare)

To decipher the molecular bases governing seed germination, this study presents the pivotal role of the cap-binding complex (CBC), comprising CBP20 and CBP80, in modulating the inhibitory effects of abscisic acid (ABA) in barley. Using both single and double barley mutants in genes encoding the CBC, we revealed that the double mutant hvcbp20.ab/hvcbp80.b displays ABA insensitivity, in stark contrast to the hypersensitivity observed in single mutants during germination. Our comprehensive transcriptome and metabolome analysis not only identified significant alterations in gene expression and splicing patterns but also underscored the regulatory nexus among CBC, ABA, and brassinosteroid (BR) signaling pathways.

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.

ATBS1-INTERACTING FACTOR 2 Positively Regulates Freezing Tolerance via INDUCER OF CBF EXPRESSION 1/C-REPEAT BINDING FACTOR-Induced Cold Acclimation Pathway.

The INDUCER OF CBF EXPRESSION 1/C-REPEAT BINDING FACTOR (ICE1/CBF) pathway plays a crucial role in plant responses to cold stress, impacting growth and development. Here, we demonstrated that ATBS1-INTERACTING FACTOR 2 (AIF2), a non-DNA-binding basic helix-loop-helix transcription factor, positively regulates freezing tolerance through the ICE1/CBF-induced cold tolerance pathway in Arabidopsis. Cold stress transcriptionally upregulated AIF2 expression and induced AIF2 phosphorylation, thereby stabilizing the AIF2 protein during early stages of cold acclimation. The AIF2 loss-of-function mutant, aif2-1, exhibited heightened sensitivity to freezing before and after cold acclimation. In contrast, ectopic expression of AIF2, but not the C-terminal-deleted AIF2 variant, restored freezing tolerance. AIF2 enhanced ICE1 stability during cold acclimation and promoted the transcriptional expression of CBFs and downstream cold-responsive genes, ultimately enhancing plant tolerance to freezing stress. MITOGEN-ACTIVATED PROTEIN KINASES 3 and 6 (MPK3/6), known negative regulators of freezing tolerance, interacted with and phosphorylated AIF2, subjecting it to protein degradation. Furthermore, transient co-expression of MPK3/6 with AIF2 and ICE1 downregulated AIF2/ICE1-induced transactivation of CBF2 expression. AIF2 interacted preferentially with BRASSINOSTEROID-INSENSITIVE 2 (BIN2) and MPK3/6 during the early and later stages of cold acclimation, respectively, thereby differentially regulating AIF2 activity in a cold acclimation time-dependent manner. Moreover, AIF2 acted additively in a gain-of-function mutant of BRASSINAZOLE-RESISTANT 1 (BZR1; bzr1-1D) and a triple knockout mutant of BIN2 and its homologs (bin2bil1bil2) to induce CBFs-mediated freezing tolerance. This suggests that cold-induced AIF2 coordinates freezing tolerance along with BZR1 and BIN2, key positive and negative components, respectively, of brassinosteroid signaling pathways.

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.

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.

Brassinosteroid-insensitive 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 regulates 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 and 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.

Transcriptomics analyses reveal the key genes involved in stamen petaloid formation in Alcea rosea L.

Alcea rosea L. is a traditional flower with a long cultivation history. It is extensively cultivated in China and is widely planted in green belt parks or used as cut flowers and potted ornamental because of its rich colors and flower shapes. Double-petal A. rosea flowers have a higher aesthetic value compared to single-petal flowers, a phenomenon determined by stamen petaloid. However, the underlying molecular mechanism of this phenomenon is still very unclear. In this study, an RNA-based comparative transcriptomic analysis was performed between the normal petal and stamen petaloid petal of A. rosea. A total of 3,212 differential expressed genes (DEGs), including 2,620 up-regulated DEGs and 592 down-regulated DEGs, were identified from 206,188 unigenes. Numerous DEGs associated with stamen petaloid were identified through GO and KEGG enrichment analysis. Notably, there were 63 DEGs involved in the plant hormone synthesis and signal transduction, including auxin, cytokinin, gibberellin, abscisic acid, ethylene, brassinosteroid, jasmonic acid, and salicylic acid signaling pathway and 56 key transcription factors (TFs), such as MADS-box, bHLH, GRAS, and HSF. The identification of these DEGs provides an important clue for studying the regulation pathway and mechanism of stamen petaloid formation in A. rosea and provides valuable information for molecular plant breeding.

The Mechanism of Exogenous Salicylic Acid and 6-Benzylaminopurine Regulating the Elongation of Maize Mesocotyl.

The elongation of the mesocotyl plays an important role in the emergence of maize deep-sowing seeds. This study was designed to explore the function of exogenous salicylic acid (SA) and 6-benzylaminopurine (6-BA) in the growth of the maize mesocotyl and to examine its regulatory network. The results showed that the addition of 0.25 mmol/L exogenous SA promoted the elongation of maize mesocotyls under both 3 cm and 15 cm deep-sowing conditions. Conversely, the addition of 10 mg/L exogenous 6-BA inhibited the elongation of maize mesocotyls. Interestingly, the combined treatment of exogenous SA-6-BA also inhibited the elongation of maize mesocotyls. The longitudinal elongation of mesocotyl cells was the main reason affecting the elongation of maize mesocotyls. Transcriptome analysis showed that exogenous SA and 6-BA may interact in the hormone signaling regulatory network of mesocotyl elongation. The differential expression of genes related to auxin (IAA), jasmonic acid (JA), brassinosteroid (BR), cytokinin (CTK) and SA signaling pathways may be related to the regulation of exogenous SA and 6-BA on the growth of mesocotyls. In addition, five candidate genes that may regulate the length of mesocotyls were screened by Weighted Gene Co-Expression Network Analysis (WGCNA). These genes may be involved in the growth of maize mesocotyls through auxin-activated signaling pathways, transmembrane transport, methylation and redox processes. The results enhance our understanding of the plant hormone regulation of mesocotyl growth, which will help to further explore and identify the key genes affecting mesocotyl growth in plant hormone signaling regulatory networks.

Genomic Analysis of Brassinosteroid Biosynthesis Gene Family Reveals Its Roles in Cotton Development across Gossypium Species.

Cotton is a globally significant economic crop. Brassinosteroids (BRs) are crucial to cotton development. This study systematically analyzed the BR synthase gene family in four cotton species and identified 60 BR genes: 20 in Gossypium hirsutum (GhBRs), 20 in G. barbadense (GbBRs), 10 in G. arboreum (GaBRs), and 10 in G. raimondii (GrBRs). The analysis was extended to chromosomal localization, evolutionary relationships, domain features, and cis-regulatory elements in the promoter regions of BR synthase genes. The results showed that the BR synthase genes were evenly distributed across different subgenomes and chromosomes. Bioinformatics analyses revealed high conservation of amino acid sequences, secondary structures, and conserved domains among the subfamily members, which is closely linked to their pivotal roles in the BR biosynthesis pathway. Cis-element distribution analysis of the BR synthase genes further underscored the complexity of BR gene expression regulation, which is influenced by multiple factors, including plant hormones, abiotic stress, and transcription factors. Expression profiling of GhBRs genes in various cotton tissues and developmental stages highlighted the key roles of GhROT3-1 and GhDET2-1 in fiber elongation and initiation, respectively. Protein-protein interactions and transcription factor analyses further elucidated the regulatory mechanisms of GhROT3-1 and GhDET2-1 in cotton growth and development. This study lays a theoretical foundation for understanding the role of the BR signaling pathway in cotton development, facilitating molecular breeding.