Genome-wide analysis of GRAS gene family and functional identification of a putative development and maintenance of axillary meristematic tissue gene PlGRAS22 in Paeonia ludlowii

The GRAS gene family, is instrumental in a myriad of biological processes, including plant growth and development. Our findings revealed that Paeonia ludlowii (Stern & G.Taylor) D.Y.Hong) harbored 45 PlGRAS genes, which are categorized into eight subfamilies. These genes are distributed across chromosomes 1 through 5, with their encoded proteins exhibiting variation in physicochemical properties. The promoter regions of the Paeonia ludlowii GRAS genes are enriched with cis-acting elements associated with growth and development, hormonal responses, and light signaling, among others. Among these genes, we have pinpointed PlGRAS22, which bears the closest resemblance to the AtLAS gene in Arabidopsis. Notably, this gene exhibits heightened expression levels within the LAS subfamily across a range of tissues, and it demonstrates an exceptionally robust response to treatments with exogenous gibberellins and cytokinins. The subdued expression of TRV2-PlGRAS22 within the flower buds of the Paeonia ludlowii has resulted in a diminished development of axillary bud primordia. Intriguingly, overexpression of PlGRAS22 in Arabidopsis led to an increase in the number of branches, highlighting its potential role in developmental processes. Furthermore, through the use of luciferase and yeast one-hybrid assays, we have demonstrated that PlGRAS22 interacts with the SPL transcription factor PlSPL3. The comprehensive analysis presented in this study lays a solid foundation for future investigations into the functional roles of Paeonia ludlowii GRAS genes and elucidates the underlying mechanisms governing growth and development in this species.