The BES1/BZR1 family is a plant-specific small group of transcription factors possessing a non-canonical bHLH domain. Genetic and biochemical analyses within the last two decades have demonstrated that members of this family are key transcription factors in regulating the expression of brassinosteroid (BR) response genes. Several recent genetic and evolutionary studies, however, have clearly indicated that the BES1/BZR1 family transcription factors also function in regulating several aspects of plant development via BR-independent pathways, suggesting they are not BR specific. In this review, we summarize our current understanding of this family of transcription factors, the mechanisms regulating their activities, DNA binding motifs, and target genes. We selectively discuss a number of their biological functions via BR-dependent and particularly independent pathways, which were recently revealed by loss-of-function genetic analyses. We also highlight a few possible future directions.

Brassinosteroids (BRs) are an essential group of plant hormones regulating numerous aspects of plant growth, development, and stress responses. BRI1, along with its co-receptor BAK1, are involved in brassinosteroid sensing and early events in the BR signal transduction cascade. Mutational analysis of a particular gene is a powerful strategy for investigating its biochemical role. Molecular genetic studies, predominantly in Arabidopsis thaliana, but progressively in numerous other plants, have identified many mutants of the BRI1 gene and its orthologs to gain insight into its structure and function. So far, the plant kingdom has identified up to 40 bri1 alleles in Arabidopsis and up to 30 bri1 orthologs in different plants. These alleles exhibit phenotypes that are identical in terms of development and growth. Here, we have summarized bri1 alleles in Arabidopsis and its orthologs present in various plants including monocots and dicots. We have discussed the possible mechanism responsible for the specific allele. Finally, we have briefly debated the importance of these alleles in the research field and the agronomically valuable traits they offer to improve plant varieties.

Plant receptor-like kinases (RLKs) constitute one of the largest and most ancient protein families in land plants. Localized on the plasma membrane, they perceive a diverse array of extracellular signals and coordinate intracellular responses that are crucial for plant growth, development, immunity, and adaptation to environmental changes. Over the past two decades, there has been an explosive expansion of knowledge regarding how RLKs govern virtually every aspect of plant life. Crucially, this knowledge has been translated into practical applications for crop improvement. Here, we summarize the conspicuous triumphs of RLK-mediated strategies in improving plant architecture and yield, enhancing biotic stress resistance against insect herbivores and microbial pathogens, as well as bolstering abiotic stress tolerance to heat, cold, drought, and salinity. We also discuss how RLKs have been utilized as precision molecular targets through genome editing, promoter engineering, and other biotechnological approaches, offering a roadmap for sustainable crop improvement.