Genome-wide identification of sugarcane SINA family proteins reveals that SsSINA1a positively regulates drought tolerance

Sugarcane ( Saccharum spp.) is an important crop for sugar and ethanol production globally, but its growth and productivity are severely affected by drought stress. SEVEN IN ABSENTIA (SINA), encoding E3 ubiquitin ligases, plays a significant role in plant stress responses. However, the characteristics of SINA family proteins in sugarcane have not been previously reported. In this study, 15 SsSINAs in Saccharum spontaneum , 5 ShSINAs in Saccharum spp. hybrid R570, and 6 SbSINAs in Sorghum bicolor were identified based on their conserved RING finger and SINA domains. Through expression analysis, SsSINA1a , a significantly upregulated SINA gene, was identified in sugarcane under drought stress. Overexpression of SsSINA1a significantly enhanced drought tolerance in Arabidopsis . RNA-sequencing analysis revealed that after drought treatment, 35.1 % of differentially expressed genes in SsSINA1a -overexpressing Arabidopsis were jasmonic acid (JA)-responsive genes, among which many genes involved in JA signaling transduction were significantly upregulated, while several jasmonate ZIM-domain ( JAZ ) genes showed obvious downregulation. Further analysis revealed that SsSINA1a interacts with sugarcane ScJAZ3 and inhibits the protein accumulation level of ScJAZ3. Together, we hypothesized that SsSINA1a improves plant drought tolerance by weakening JAZ protein accumulation and activating JA signaling. This study provides a new candidate gene for sugarcane drought-resistance breeding and an enriched understanding of SINA protein-mediated drought tolerance through JA signaling. • 15 SsSINA genes identified in sugarcane S . spontaneum genome. • First sugarcane SINA analysis E3 ligasestudy and breeding. • SsSINA1a boosts drought tolerance and JA signaling in Arabidopsis . • SsSINA1a binds ScJAZ3, reducing its level to activate JA signaling.