Insights into ZmWAKL in Maize Kernel Development: Genome-wide Investigation and GA-Mediated Transcription

Abstract

Abstract Background The functional roles of the WAK and WAKL kinase families in cellular expansion and developmental processes have been well-established. However, the molecular regulation of these kinases in maize development has been limited due to the absence of comprehensive genome-wide studies. Results In this investigation, we performed an in-depth analysis to identify 58 maize WAKL genes, classified into three distinct phylogenetic clusters. Moreover, through structural prediction analysis, we revealed functional conservation among WAKLs across maize. Promoter analysis uncovered the existence of cis-acting elements associated with the transcriptional regulation of ZmWAKL genes by Gibberellic acid (GA). To further elucidate the role of WAKL genes in maize kernels, we focused on three highly expressed genes, ZmWAKL38, ZmWAKL42 and ZmWAKL52, and conducted co-expression and expression analyses. Remarkably, their expression patterns exhibited a strong correlation with GA-responsive transcription factors TF5, TF6, and TF8, which displayed preferential expression in kernels. RT-qPCR analysis validated the upregulation of ZmWAKL38, ZmWAKL42, ZmWAKL52, TF5, TF6, and TF8 following GA treatment. Additionally, ZmWAKL52 promoter showed significant increase of transcriptional activity in the present of TF8, with ZmWAKL52 localized in both the plasma membrane and cell wall. TF5 positively regulated ZmWAKL38, while TF6 positively regulated ZmWAKL42. Conclusions Collectively, these findings provide novel insights into the characterization and regulatory mechanisms of specific ZmWAKL genes involved in maize kernel development, offering prospects for their utilization in maize breeding programs.