The Novel Use of a Combination of Sonication and Vacuum Infiltration in <i>Agrobacterium</i>-mediated Transformation of Kidney Bean (<i>Phaseolus vulgaris</i> L.) with <i>lea</i> Gene

An efficient gene transfer system without tissue culture steps was developed for kidney bean by using sonication and vacuum infiltration assisted, Agrobacterium -mediated transformation. Transgenic kidney bean with a group 3 lea (late embryogenesis abundant) protein gene from Brassica napus was produced through this approach. Among 18 combinations of transformation methods, Agrobacterium -mediated transformation combined with 5 min sonication and 5 min vacuum infiltration turned to be optimal, resulting in the highest transformation efficiency. Transgenic kidney bean plants demonstrated enhanced growth ability under salt and water deficit stress conditions. The increased tolerance was also reflected by delayed development of damage symptoms caused by drought stress. Transgenic lines with high level of lea gene expression showed higher stress tolerance than lines with lower expression level. Stress tolerance of transgenic kidney bean correlated much better with lea gene expression levels than with gene integration results. There is no prior report on the production of transgenic kidney bean using both ultrasonic and vacuum infiltration assisted, Agrobacterium -mediated transformation.