Genome-wide characterization of the SnRK gene family in jujube (Ziziphus jujuba Mill.) reveals that ZjSnRK7 and ZjSnRK9 may contribute to salt stress tolerance

Abstract

During the plant life cycle, biotic and abiotic stresses critically influence survival and development. Sucrose non-fermenting 1-related protein kinases (SnRKs)-a conserved class of key signaling regulators-play a central role in stress response mechanisms shaped by long-term plant evolution. However, systematic genomic characterization of the SnRK gene family in the jujube tree ( Ziziphus jujuba Mill.) remains lacking. In this study, comprehensive bioinformatic analyses identified 17 ZjSnRK genes in the jujube T2T genome; these genes were unevenly distributed across seven chromosomes. Phylogenetic analysis classified them into four distinct subfamilies. Expression profiling revealed that individual ZjSnRK members exhibited divergent transcriptional responses to salt stress. Agrobacterium-mediated transient over-expression and virus-induced gene silencing (VIGS) of ZjSnRK7 and ZjSnRK9 were employed as an initial approach to explore their potential involvement in salt-stress responses. Under salt stress, transiently transformed plants exhibited ~about 2-fold (over-expression) or ~0.7-fold (silencing) expression levels of ZjSnRK7/9 relative to wild-type (WT) controls. Survival and wilting rates were quantified: WT plants showed ~60% survival and ~60% wilting (reflecting partial overlap due to scoring methodology); ZjSnRK7/9 -over-expressing transiently transformed plants displayed ~90% survival and ~10% wilting; whereas silenced transiently transformed plants exhibited only ~10% survival and ~90% wilting. Collectively, these results provide preliminary evidence that over-expression of either ZjSnRK7 or ZjSnRK9 may be associated with enhanced salt tolerance, whereas their suppression may increase salt sensitivity. This study presents the first genome-wide identification and integrative analysis of the ZjSnRK gene family in jujube. The findings offer an initial framework for further investigating the potential biological functions of ZjSnRK genes and may serve as a reference for future studies on stress responses in jujube and related species.