Overexpression of GmBI-1b gene from Glycine max improves drought tolerance in soybean.

Drought stress affects plant growth, and it can directly kill plants in severe cases. Drought stress is one of the major abiotic stresses affecting soybean growth and yield. The Bax Inhibitor-1 (BI-1) can inhibit cell death mediated by both biotic and abiotic stresses. However, the function of GmBI-1 genes from soybean remains unclear under drought stress. In this study, we found four GmBI-1 genes in soybean, and the GmBI-1b was significantly induced under drought stress at RNA and protein levels. The expression level of GmBI-1b was highest in leaves, and the GmBI-1b protein was localized to the endoplasmic reticulum. Overexpression of GmBI-1b enhanced drought tolerance in soybeans by reducing cell death under drought stress. Transcriptome sequencing (RNA-seq) revealed that GmBI-1b contributes to drought tolerance, which is associated with the upregulation of ABA-related genes, cell death suppression genes and aquaporin genes.