Genome-wide identification of SINA gene family in sugarcane and functional analysis of SsSINA1a in drought response

Sugarcane (Saccharum spp. hybrid) is a crucial sugar and energy crop that provides majority of the raw material for sugar and ethanol production globally. Drought represents one of the most critical constraints of sugarcane production in the subtropical parts of China. SEVEN IN ABSENTIA (SINA) act as an important E3 ubiquitin ligase and play a significant role in plant stress responses. However, the characteristics of the sugarcane SINA gene family have not been previously studied currently. Here, we identified 15 SsSINA in Saccharum spontaneum, 5 ShSINA in Saccharum spp. hybrid and 6 SbSINA in Sorghum bicolor based on their conserved N{square}terminal RING and C-terminal SINA domains, and these genes were distributed into three phylogenetic groups (I, {square} and {square}). Collinearity analysis showed a close genetic relationship between the SINA genes of S. spontaneum and S. bicolor. The cis-regulatory elements in the promoter regions of the SINA genes were involved in a variety of plant physiological responses. Further, we identified a SINA gene SsSINA1a that significantly induced by drought stress. Overexpression of SsSINA1a enhanced drought tolerance in Arabidopsis through reducing leaf water loss rate. These finding indicate that SsSINA1a mediates plant drought tolerance and this study provides a new potential candidate gene for sugarcane drought-resistant breeding.