ZmWRKY82-ZmSLG regulate seed development by modulating brassionsteroid homeostasis in maize

Seed development is a crucial biological process affecting crop yield. Brassionsteroids (BRs) plays essential role in seed development. Although part of genes participated in BR regulate seed development have been cloned in maize, their genetic and mechanisms are still unclear. In the previous experiment, we found that exogenous spray BL promote seed development. Here, RNA-sequence analysis of BL treated seeds revealed that 12 candidate function genes and 62 candidate transcription factors among the differentially expressed genes (DEGs) were regulated by BL. Combining with previous QTL and GWAS research results in maize and homologous gene analysis, ZmSLG1 was screened out from 12 candidate function genes for further study. Overexpression of ZmSLG1 displayed round seed and delayed embryo development in maize. Moreover, overexpression of ZmSLG1 decreased BR content and increased expression of BR synthesis related genes in seed. To understand the mechanism of BL regulating ZmSLG1 expression, ZmWRKY82 was identified from 62 candidate transcription factors and examined its function. Transient expression, EMSA and ChIP analysis showed ZmWRKY82 can directly bind to the ZmSLG1 promoter to regulate ZmSLG1 expression. Collectively, exogenous BL regulate the ZmSLG1 gene expression through ZmWRKY82 transcription factor, and ZmSLG1 negatively regulates the endogenous BR contents in seed. Highlight We conclude that ZmWRKY82-ZmSLG1 is required for BR homeostasis and that modification of ZmSLG1 expression to an appropriate level may provide a way to increase yield. ### Competing Interest Statement The authors have declared no competing interest. * (BRs) : Brassionsteroids (BL) : Brassinolide (CS) : Castasterone (6-deoc-oCS) : 6-deoxocastasterone (DAP) : days after pollination