Genome-wide identification of the TIFY gene family in Sorghum bicolor and functional characterization of SbTIFY9 in salt stress tolerance.

Abstract

The TIFY gene family is a plant-specific group of transcriptional regulators characterized by a conserved TIFY domain (TIF[F/Y]XG), participating in plant development, phytohormone signaling and abiotic stress responses. In this study, 21 SbTIFY genes were genome-widely identified in sorghum (Sorghum bicolor L.). According to phylogeny and protein structures, SbTIFY proteins were grouped into JAZ and ZML subfamilies, and the JAZ subfamily was further divided into five clades. These proteins contain 101-429 amino acids and are unevenly distributed across six chromosomes. Genes from the same subgroup possess similar exon-intron structures and conserved motifs. Promoter analysis uncovered abundant cis-elements associated with hormone signaling, stress responses and developmental processes. Synteny analysis detected seven orthologous pairs between sorghum and Arabidopsis, and 25 pairs between sorghum and rice (Oryza sativa). Expression profiling revealed that multiple SbTIFY members exhibited differential expression across developmental organs and under stresses including anthracnose infection, cold, heat, flooding, and salt. SbTIFY9 displayed strong induction under multiple stresses: its transcript level increased approximately 10-fold at 12h and approximately 31-fold at 24h of salt treatment, implying its vital function in salt response. Subcellular localization confirmed SbTIFY9 resides mainly in the nucleus. Heterologous overexpression of SbTIFY9 in Arabidopsis improved true leaf expansion, fresh weight at germination, and root growth and biomass at seedling stage under 125 and 150mM NaCl, demonstrating its positive role in salt tolerance. This work provides insights into the evolution and stress functions of sorghum TIFY family.