Reciprocal inhibition of expression between RAV1 and BES1 modulates plant growth and development in Arabidopsis.

Dami Yang, Hyun-Young Shin, Hyun Kyung Kang, Yun Shang, So Young Park, Dong-Hoon Jeong, Kyoung Hee Nam

Journal of integrative plant biology 2023 May

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RAV1 (Related to ABI3/VP1) is a plant-specific B3 and AP2 domain-containing transcription factor that acts as a negative regulator of growth in many plant species. The expression of RAV1 is downregulated by brassinosteroids (BRs); large-scale transcriptome analyses have shown that the expression of RAV1 was previously targeted by BRI1-EMS-SUPPRESOR1 (BES1) and BRASSINAZOLE-RESISTANT1 (BZR1), which are critical transcription factors for the BR-signaling process. Using RAV1-overexpressing transgenic plants, we showed that RAV1 overexpression reduced the BR signaling capacity, resulting in the downregulation of BR biosynthetic genes and BES1 expression. Furthermore, we demonstrated that BES1, not BZR1, is directly bound to the RAV1 promoter and repressed RAV1 expression, and vice versa; RAV1 is also bound to the BES1 promoter and repressed BES1 expression. This mutual inhibition was specific to RAV1 and BES1 because RAV1 exhibited binding activity to the BZR1 promoter but did not repress BZR1 expression. We observed that constitutively activated BR signaling phenotypes in bes1-D were attenuated by the repression of endogenous BES1 expression in transgenic bes1-D plants overexpressing RAV1. RNA-sequencing analysis of RAV1-overexpressing transgenic plants and bes1-D mutant plants revealed differentially expressed genes by RAV1 and BES1 and genes that were oppositely co-regulated by RAV1 and BES1. RAV1 and BES1 regulated different transcriptomes but co-regulated a specific set of genes responsible for the balance between growth and defense. These results suggested that the mutual inhibitory transcriptional activities of RAV1 and BES1 provide fine regulatory mechanisms for plant growth and development. © 2022 The Authors. Journal of Integrative Plant Biology published by John Wiley & Sons Australia, Ltd on behalf of Institute of Botany, Chinese Academy of Sciences.

Citation

Dami Yang, Hyun-Young Shin, Hyun Kyung Kang, Yun Shang, So Young Park, Dong-Hoon Jeong, Kyoung Hee Nam. Reciprocal inhibition of expression between RAV1 and BES1 modulates plant growth and development in Arabidopsis. Journal of integrative plant biology. 2023 May;65(5):1226-1240