Evolutionary and functional characterization of tea plant DELLA proteins

DELLA proteins function as key negative regulators in gibberellin signaling, driving numerous molecular mechanisms that impact plant morphogenesis and ontogeny. In this study, eight representative DELLA proteins were identified based on pan-genome analysis of Camellia sinensis var. assamica (CSA) and Camellia sinensis var. sinensis (CSS). Phylogenetically, these DELLA proteins were subdivided into five groups, and their evolutionary trajectories were systematically investigated. Five DELLA proteins identified in Longjing43, including a newly discovered CsDELLA5, were found to be crucial for growth and exhibited distinct expression patterns in different tissues of tea plant during seasonal transitions. The five proteins were mainly located in the nucleus, CsDELLA2 exhibited a spotted distribution in the cytoplasm. CsDELLAs also showed varied protein structure, hormone responses and expression patterns in bud sprouting. Notably, the presence of GAs significantly enhanced the interaction between CsDELLA2/4/5 and CsGID1a/b. Inhibition of the expression of CsDELLA2 and CsDELLA4 significantly increase the bud sprouting rate indicating a negative function in regulation of bud break. This study offers valuable insights into the roles of DELLA proteins in tea plants and provides a theoretical foundation for DELLA protein research in other species.