Origin and evolution of BZR gene family in plants, pan-genome analysis of the BZR1 gene family, and functional characterization of CaBZR1.2 in pepper lateral branch development

Abstract

The transcription factor BRASSINAZOLE-RESISTANT1 ( BZR1 ) plays a crucial role not only in plant responses to various biotic and abiotic stresses but also serves a critical function in plant growth and development. In this study, we analyzed the origin and evolution of the BZR family in plants. Then, we identified nine CaBZR1 genes from the pepper pan-genome and performed bioinformatics analyses. Through the integration of transcriptome data analysis with our prior bioinformatics findings, we have identified and selected a specific member of the CaBZR1 family, CaBZR1.2 , for further comprehensive investigation. We systematically investigated the biological function of CaBZR1.2 in pepper through classical reverse genetics approaches and subsequently identified proteins that interact with CaBZR1.2. After inhibiting the expression of CaBZR1.2 via virus-induced gene silencing (VIGS), the growth of pepper lateral branches was significantly suppressed, whereas heterologous overexpression of CaBZR1.2 increased lateral branch number in tomato. This result confirms the key role of CaBZR1.2 in the development of pepper lateral branches. Furthermore, protein–protein interaction assays confirmed that the Sucrose Nonfermenting 1-Related Protein Kinase 1 β subunit 2 (CaSnRK1 β 2) protein interacts with CaBZR1.2, with subsequent analyses revealing that these two proteins modulate pepper lateral branch development through a mutually antagonistic regulatory mechanism. This study reveals a novel mechanism by which CaBZR1.2 and CaSnRK1 β 2 coordinately regulate lateral branch development in pepper, providing candidate genes and a theoretical basis for the molecular breeding for pepper plant architecture.

Acknowledgements

This research was funded by National Nature Science Foundation of China (U22A20497, 32341047, 32302574), Hunan Provincial Natural Science Foundation (2025JJ40022), and Natural Science Foundation of Changsha (kq2506023).

Author contributions

Z.L., L.O., X.D., and W.X. conceived and supervised the research. W.X., D.Z., P.L., Q.C., L.M., Y.Z., and J.D. performed the experiments. Q.C., Y.L., X.H., and W.X. conducted database collation and bioinformatics analysis. W.X. and Z.L. drafted the manuscript. Y.L., S.Y., C.X., X.Z., X.D., L.O., and Z.L. revised the manuscript.

Data availability

The data that supports the findings of this study is available in the supplementary material of this article.

Conflicts of interest statement

The authors declare no conflicts of interest.

Supplementary material

Supplementary material is available at Horticulture Research online.

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