Definition of RING gene family in sugar beet (Beta vulgaris L.) and functional characterization of BvRING-HCa-9 in plant salt stress tolerance

Abstract Background RING-type E3 ligases are key enzymes in protein ubiquitination modification and crucial regulators in plant growth and development. However, their roles in sugar beet ( Beta vulgaris L.) remain unclear. To determine the types and distribution of RING-type proteins in sugar beet, we conducted a comprehensive analysis of the RING family genes. By analyzing RING gene expression profiles under salt stress, a candidate gene ( BvRING-HCa-9 ) associated with salt stress was identified. The goal is to characterize the functions of the sugar beet RING gene family in plant salt stress tolerance. Results A total of 446 RING-type proteins in the sugar beet genome were identified. The coding genes are distributed across all nine chromosomes, with varying expression patterns among subtypes. Collinearity and Ka/Ks analyses suggest that the RING family in sugar beet has undergone limited duplication events and is under strong purifying selection, indicating evolutionary conservation. Many BvRING genes are transcriptionally responsive to salt stress. Among them, Bv RING-HCa-9 possesses ubiquitin E3 ligase activity and is localized in the nucleus and plasma membrane. Overexpression of BvRING-HCa-9 in transgenic Arabidopsis enhanced salt tolerance. Conclusion The 446 RING-domain genes in sugar beet are evolutionarily conserved, and majority of the genes are transcriptionally responsive to salt stress. Among them, BvRING-HCa-9 was characterized to encode a E3 ligase and it plays an important role in plant salt tolerance. These findings provide a valuable resource for functional studies of other RING family genes in plant stress resilience.