Drought tolerance test
Four-month-old plants were used for drought tolerance test in a greenhouse. We weighed the total weight of nutrient soil and plant in the flower pot after watering to the maximum (100%) water holding capacity (WHC) of soil before drought treatment. Then, control water treatment was given till WHC was reduced to 50%. The date was recorded as 0 d of drought treatment. We tested the leaf physiological parameters at 0 d, 7 d, and 10 d after drought treatment. Nine S0-0 and nine S0-50 plants were randomly selected and divided into three groups as three biological replicates to evaluate plant drought tolerance. As to the transgenic plants overexpressing AtSOAR1 , three plants propagated by cuttage of each line were treated as a biological repeat.