GABA transporter OsGAT3 is required for growth and yield in rice under salt and drought stress

Gama-aminobutyric acid (GABA) plays an important role in regulating plant growth and response to various stresses. Here, we studied the natural variation of GABA transporter gene OsGAT3 in rice germplasm and found four primary promoter haplotypes. OsGAT3 was highly expressed in roots, culms, and leaf blades and was strongly induced in roots by GABA, salt, drought, and low temperature. OsGAT3 expression level was positively correlated with tiller number and nitrogen utilization efficiency (NUtE). OsGAT3 was localized in the plasma membrane. Overexpression of OsGAT3 significantly promoted GABA accumulation in basal parts suggesting it boosted axillary bud formation, tillering, and grain yield. OsGAT3 overexpression also enhanced tolerance to drought and salt stress. Transcriptome analysis revealed enriched phenylpropanoid and pentose phosphate pathways, and MAPK signaling underlining tolerance to salt stress, whereas drought tolerance was attributed to enhanced photosynthesis, glyoxylate and dicarboxylate metabolism, and carotenoid biosynthesis. Taken together, our data support the potential application of the gene for increasing yield under abiotic tolerance.