Overexpression of AtYUCCA6 in soybean crop results in reduced ROS production and increased drought tolerance

Drought is a major abiotic stress in crop yield and its inevitable consequence is the increased production of reactive oxygen species (ROS) and cell damage. To reduce excessive ROS accumulation in soybean, AtYUCCA6 gene was transformed via Agrobacterium-mediated transformation. About 3% of transformation efficiency was generated from five batches of the transformation experiment. Eighteen transgenic plants were produced with PPT resistance and analyzed for introgression of AtYUCCA6. T-DNA insertion and expression were confirmed by PCR, Southern blot and reverse transcriptase-PCR. In the drought tolerance tests with transgenic lines #2, #3, and #5, all three lines were less affected by drought treatment and survived in the water-deficit conditions while non-transgenic plants did not survive under the same drought condition. The physiological aspects of transgenic lines were also much stronger than NT plants by showing higher chlorophyll content and lower ion leakage during water-deficit conditions (p<0.01), indicating the prevention of cell-membrane damage. Measurement of transpiration rate on detached leaves from transgenic plants showed nearly 10% less water loss. Finally, 3 transgenic lines (#2, #3, and #5) were investigated for ROS accumulation by DAB staining of detached leaves under water-deficit conditions. Unlikely NT plants with severe dark browning after 14 days of drought treatment, transgenic lines #2, #3, and #5 did not show significant browning.