Genome-wide identification of the RLCK gene family in sugarcane and functional analysis of ScRLCK53 in salt tolerance.

Abstract

Sugarcane (Saccharum spp.) is a major sugar crop, yet its growth and yield are frequently limited by soil salinization. Receptor-like cytoplasmic kinases (RLCKs) act as central signaling hubs in plants, regulating growth, development, immunity, and abiotic stress responses. However, the evolution of the RLCK gene family in sugarcane and its role in salt tolerance remain unclear. Using the high-quality genome of elite cultivar 'Zhongzhe No.1', we identified 262 ScRLCK genes, grouped into 15 subfamilies, all of which contain a typical protein kinase domain. Synteny analysis revealed that whole-genome and segmental duplications were the primary drivers of ScRLCK family expansion, accounting for 67.9% duplication events, while purifying selection predominated during their evolutionary trajectory. T Transcriptome profiling revealed widespread differential expression of ScRLCK genes under hormonal treatments and abiotic stresses; notably, ScRLCK53 was strongly upregulated by salt and other stresses. Functional characterization confirmed nuclear localization of the ScRLCK53. Transgenic Arabidopsis lines displayed markedly enhanced seed germination rates and increased seedling fresh weight under salt stress. Moreover, these overexpression lines exhibited heightened sensitivity to jasmonic acid (JA), accompanied by elevated endogenous JA levels, pronounced upregulation of key JA signaling markers, and enhanced expression of canonical salt-responsive genes. This study represents the first comprehensive characterization of the RLCK gene family in sugarcane, elucidating its evolutionary features, expression dynamics and functional roles, and provides compelling evidence that ScRLCK53 modulates salt tolerance through activation of the JA signaling pathway, providing a theoretical foundation and valuable genetic resources for the genetic enhancement of stress tolerance in sugarcane.