Positively Regulates Drought Tolerance and Enhanced Stomatal Response through the MAPK Signaling Pathway in Soybean.

Drought stress is one of the significant abiotic stresses that limit soybean ( [L.] Merr.) growth and production. Ankyrin repeat (ANK) proteins, being highly conserved, occupy a pivotal role in diverse biological processes. genes were classified into nine subfamilies according to conserved domains in the soybean genome. However, the function of ANK-TM subfamily proteins (Ankyrin repeat proteins with a transmembrane domain) in the abiotic-stress response to soybean remains poorly understood. In this study, we first demonstrated the subcellular localization of GmANKTM21 in the cell membrane and nucleus. Drought stress-induced mRNA levels of , which encodes proteins belonging to the ANK-TM subfamily, Transgenic soybean improved drought tolerance at the germination and seedling stages, with higher stomatal closure in soybean, lower water loss, lower malondialdehyde (MDA) content, and less reactive oxygen species (ROS) production compared with the wild-type soybean (Dongnong50). RNA-sequencing (RNA-seq) and RT-qPCR analysis of differentially expressed transcripts in overexpression of further identified potential downstream genes, including , , and , which showed higher expression in transgenic soybean, than those in wild-type soybean and KEGG enrichment analysis showed that MAPK signaling pathways were mostly enriched in overexpressing soybean plants under drought stress conditions. Therefore, we demonstrate that plays an important role in tolerance to drought stress in soybeans.