Genome-wide characterization of soybean bile acid: sodium symporter genes reveals a positive role of GmBASS2-2 in salt stress response.

The bile acid: sodium symporter (BASS) plays a pivotal role in plant growth, development, and response to abiotic stress. In this study, eight members of the BASSs group were identified through genome-wide screening. Additionally, employing phylogenetic analysis allowed for the categorization of the BASS gene family into five distinct subfamilies. The localization of GmBASSs in young tobacco leaves was primarily observed within chloroplasts using confocal microscopy. The qRT-PCR analysis revealed that a significant response was observed in the majority of GmBASSs genes toward abiotic stress, such as NaCl, NaHCO, and 20% PEG6000. The GmBASSs gene was also observed to display distinct expression patterns across various tissue. It is noteworthy that the GmBASS2-2 gene exhibits a remarkably high level of upregulation in response to salt stress, suggesting its pivotal role in mediating salt stress responses. The GmBASS2-2 gene was cloned and overexpressed in soybean hair roots and Saccharomyces cerevisiae. We found the GmBASS2-2 overexpressing Saccharomyces cerevisiae grew better than the control (pYES3 empty vector) under salt stress. The transgenic soybean plants overexpressing the GmBASS2-2 gene demonstrated superior growth compared to control plants. Gene-based association analysis showed that a total of 2 haplotypes were identified for the GmBASS2-2 gene, and Hap2 haplotype has emerged as a superior allele for enhancing salt tolerance. The above findings suggest that the GmBASS2-2 gene might be involved in the process of soybean tolerance to salt stress. The findings of this study may provide valuable insights into the regulatory mechanisms of GmBASS2-2 in response to salt stress in soybean.