Expression of the Arabidopsis AtMYB44 gene confers drought/salt-stress tolerance in transgenic soybean

AtMYB44, a member of the subgroup 22 R2R3 MYB transcription factors, positively regulates abscisic acid signaling to induce stomatal closure, thus conferring drought/salt-stress tolerance in Arabidopsis thaliana. In this study, AtMYB44 was transformed into soybean [Glycine max (L.) Merrill] using the cotyledonary-node method. The resulting homozygous lines were shorter than the non-transgenic controls (Bert) throughout the growth period when grown in a greenhouse. The transgenic soybeans exhibited significantly enhanced drought/salt-stress tolerance, as observed in Arabidopsis. In field cultivation studies, the transgenic soybean plants showed reduced growth, but much higher yields upon seed harvest, demonstrating improved environmental stress tolerance. The amino acid and fatty acid compositions were not significantly altered in seeds harvested from the transgenic lines. These results suggest that the interaction of AtMYB44 with specific sequences in target gene promoters and/or specific proteins activates a tolerance mechanism that is conserved in Arabidopsis and soybean.