GSE202679
RAV1 and BES1 mutually inhibit each other's expression and oppositely co-regulate the genes for growth and defense in Arabidopsis
RAV1 (RELATED TO ABI3/VP1) is a plant-specific B3 domain and AP2 domain-containing transcription factor and acts as a negative regulator of growth in many plant species. Expression of the RAV1 was down-regulated by BR, and through the large-scale transcriptome analyses its expression was previously shown to be targeted by BES1 and BZR1 that are critical transcription factors for BR-signaling process. Using the RAV1-overexpressing transgenic plants, here we showed that RAV1 overexpression reduced BR signaling capacity, resulting in the up-regulation of BR biosynthetic genes and down regulation of BES1 expression. Furthermore, we demonstrated that BES1, not BZR1, directly bound to the RAV1 promoter and repressed RAV1 expression, and vice versa, RAV1 also bound to the BES1 promoter and repressed BES1 expression. This mutual inhibition was specific to between RAV1 and BES1, because RAV1 showed binding activity to BZR1 promoter but did not repressed BZR1 expression. To validate this mutual inhibition of RAV1 and BES1, we generated transgenic bes1-D plants overexpressing RAV1 and observed that constitutively activated BR-signaling phenotypes in bes1-D were attenuated due to the repression of endogenous BES1 expression. To investigate transcriptomic expressional changes that are regulated by RAV1 and BES1, we performed RNA-sequencing analysis from RAV1-overexpressing transgenic plants and bes1-D mutant plant. We identified differentially expressed genes (DEGs) by RAV1 and BES1, respectively, as well as the genes that are oppositely co-regulated by RAV1 and BES1. And we found that RAV1 and BES1 regulate different transcriptome but co-regulate a specific set of genes that are responsible for the balance between growth and defense. Taken together, these results suggested that mutual inhibitory transcriptional activities of the RAV1 and BES1 provide fine regulatory mechanisms for plants growth and development mediated by BR signaling. Overall design: Examinination of mRNA expression patterns in Arabidopsis RAV1 over-expression lines and bes1-D mutants