The divergence of brassinosteroid sensitivity between rice subspecies involves natural variation conferring altered internal auto-binding of OsBSK2

Brassinosteroids in cotton: orchestrating fiber development

Cotton cultivation spans over 30 million hectares across 85 countries and regions, with more than half participating in the global cotton textile trade. The elongated cotton fiber cell is an ideal model for studying cell elongation and understanding plant growth and development. Brassinosteroids (BRs), recognized for their role in cell elongation, offer the potential for improving cotton fiber quality and yield. Despite extensive research highlighting BR's positive impact on fiber development, a comprehensive review on this topic has been lacking. This review addresses this gap, providing a detailed analysis of the latest advancements in BR signaling and its effects on cotton fiber development. We explore the complex network of BR biosynthesis components, signaling molecules, and regulators, including crosstalk with other pathways and transcriptional control mechanisms. Additionally, we propose molecular strategies and highlight key genetic elements for optimizing BR-related genes to enhance fiber quality and yield. The review emphasizes the importance of BR homeostasis and the hormonal landscape during cotton fiber development, offering insights into targeted manipulation opportunities and challenges. This consolidation offers a comprehensive understanding of BR's multifaceted roles in fiber development, outlining a strategic approach for BR optimization in cotton fiber quality and yield.

Brassinosteroid biosynthesis and signaling: Conserved and diversified functions of core genes across multiple plant species

Brassinosteroids (BRs) are important regulators that control myriad aspects of plant growth and development, including biotic and abiotic stress responses, such that modulating BR homeostasis and signaling presents abundant opportunities for plant breeding and crop improvement. Enzymes and other proteins involved in the biosynthesis and signaling of BRs are well understood from molecular genetics and phenotypic analysis in Arabidopsis thaliana; however, knowledge of the molecular functions of these genes in other plant species, especially cereal crop plants, is minimal. In this manuscript, we comprehensively review functional studies of BR genes in Arabidopsis, maize, rice, Setaria, Brachypodium, and soybean to identify conserved and diversified functions across plant species and to highlight cases for which additional research is in order. We performed phylogenetic analysis of gene families involved in the biosynthesis and signaling of BRs and re-analyzed publicly available transcriptomic data. Gene trees coupled with expression data provide a valuable guide to supplement future research on BRs in these important crop species, enabling researchers to identify gene-editing targets for BR-related functional studies.

Carotenoid isomerase regulates rice tillering and grain productivity by its biosynthesis pathway

Carotenoid isomerase activity and carotenoid content maintain the appropriate tiller number, photosynthesis, and grain yield. Interactions between the strigolactone and abscisic acid pathways regulates tiller formation.

Leveraging brassinosteroids towards the next Green Revolution

The use of gibberellin-related dwarfing genes significantly increased grain yield during the Green Revolution. Brassinosteroids (BRs) play a vital role in regulating agronomic traits and stress resistance. The potential of BR-related genes in crop improvement has been well demonstrated, positioning BRs as crucial targets for the next agricultural biotechnological revolution. However, BRs exert pleiotropic effects on plants, and thus present both opportunities and challenges for their application. Recent research suggests promising strategies for leveraging BR regulatory molecules for crop improvement, such as exploring function-specific genes, identifying beneficial alleles, inducing favorable mutations, and optimizing spatial hormone distribution. Advancing our understanding of the roles of BRs in plants is imperative to implement these strategies effectively.

BRASSINOSTEROID-SIGNALING KINASE1-1, a positive regulator of brassinosteroid signalling, modulates plant architecture and grain size in rice

Brassinosteroids (BRs) are a crucial class of plant hormones that regulate plant growth and development, thus affecting many important agronomic traits in crops. However, there are still significant gaps in our understanding of the BR signalling pathway in rice. In this study, we provide multiple lines of evidence to indicate that BR-SIGNALING KINASE1-1 (OsBSK1-1) likely represents a missing component in the BR signalling pathway in rice. We showed that knockout mutants of OsBSK1-1 are less sensitive to BR and exhibit a pleiotropic phenotype, including lower plant height, less tiller number and shortened grain length, whereas transgenic plants overexpressing a gain-of-function dominant mutant form of OsBSK1-1 (OsBSK1-1A295V) are hypersensitive to BR, and exhibit some enhanced BR-responsive phenotypes. We found that OsBSK1-1 physically interacts with the BR receptor BRASSINOSTEROID INSENSITIVE1 (OsBRI1), and GLYCOGEN SYNTHASE KINASE2 (OsGSK2), a downstream component crucial for BR signalling. Moreover, we showed that OsBSK1-1 can be phosphorylated by OsBRI1 and can inhibit OsGSK2-mediated phosphorylation of BRASSINOSTEROID RESISTANT1 (OsBZR1). We further demonstrated that OsBSK1-1 genetically acts downstream of OsBRI1, but upstream of OsGSK2. Together, our results suggest that OsBSK1-1 may serve as a scaffold protein directly bridging OsBRI1 and OsGSK2 to positively regulate BR signalling, thus affecting plant architecture and grain size in rice.

Identification, evolution, and expression analysis of OsBSK gene family in Oryza sativa Japonica

BACKGROUND

As an essential component of the BR (brassinosteroid) signaling pathway, BSK (BR-signalling kinases) plays a vital role in plant growth, development, and stress regulation. There have been sporadic reports on the functions of members of this family in monocotyledonous model plant rice, but few reports have been reported on the phylogenetic analysis and gene expression profiling of the family genes.

RESULTS

In this study, a total of 6 OsBSK members were identified at the genomic level by bioinformatics methods, distributed on four rice chromosomes. Through the evolution analysis of 74 BSK proteins from 22 species, it was found that BSKs originated from higher plants, were highly conserved, and could be divided into six subgroups. Among them, OsBSKs belonged to four subgroups or two significant groups. OsBSK family gene promoters contained a large number of light, abscisic acid (ABA), and methyl jasmonate (MeJA) response-related elements. At the same time, the qRT-PCR test also showed that the genes of this family were involved in response to a variety of hormones, biotic and abiotic stress treatments, and expression patterns of the family gene can be roughly divided into two categories, which were similar to the tissue expression patterns of genes in different growth stages. OsBSK1-1, OsBSK1-2, and OsBSK3 were mostly up-regulated. OsBSK2, OsBSK4, and OsBSK5 were mostly down-regulated or had little change in expression.

CONCLUSIONS

This study revealed the origin and evolution of the BSK family and the farm-out of BSKs in rice growth, development, and stress response. It provides the theoretical reference for in-depth analysis of BR hormone, signal transduction, and molecular breeding design for resistance.