Comprehensive Analysis of Annexin Family from Tetragonia tetragonoides and Its Initial Functions in Abiotic Stress...

Tetragonia tetragonoides is a valuable medicinal and nutritional wild plant and a typical tropical euhalophyte, exhibiting strong tolerance to salinity, alkalinity, drought, and heat. Plant annexins play critical roles in plant growth, development, and stress responses; however, the characteristics and stress-responsive patterns of the annexin (TtAnn) gene family in T. tetragonoides remain largely unclear. This study aimed to systematically characterize the TtAnn family and explore its functions in abiotic stress tolerance. A total of 15 TtAnn members were identified at the genome-wide level, followed by phylogenetic classification, chromosomal distribution analysis, duplication pattern characterization, cis-acting element prediction, and organ-specific as well as stress-induced expression profiling. Five TtAnn genes were further cloned and heterologously expressed in yeast for stress tolerance validation. The 15 TtAnns were classified into four subgroups and unevenly distributed across nine chromosomes, with whole-genome duplication serving as the predominant mechanism driving gene expansion. Their promoter regions contained multiple cis-elements related to light, hormones, and transcription factors. TtAnns exhibited root-preferential expression and showed distinct differential expression patterns under salt, alkali, osmotic, and heat stresses. Transgenic yeast assays further confirmed their roles in stress resistance. This study elucidates the fundamental features of the TtAnn family and provides valuable gene resources and a theoretical basis for dissecting abiotic stress mechanisms and genetically improving stress-tolerant crops.