A simple and efficient Agrobacterium-mediated in planta transformation protocol for horse gram (Macrotyloma uniflorum Lam. Verdc.)

BACKGROUND: Recalcitrant nature is a major constraint for the in vitro regeneration and genetic transformation of leguminous species members. Therefore, an improved genetic transformation in horse gram has been developed via in planta method, in which Agrobacterium strain harboring binary vector pCAMBIA2301 was used for the transformation. Several factors affecting in planta transformations were put forth viz. Agrobacterium cell density, co-cultivation, and sonication combined with vacuum infiltration duration which were optimized. RESULTS: Germinated seeds were sonicated and vacuum infiltrated with different densities of Agrobacterium culture and co-cultivated in half-strength MS medium with 100 μM of acetosyringone for 48 h. Seedlings were washed with cefotaxime and sowed in vermiculite soil for maturation. T(1) plants were subjected to histochemical and molecular analysis to ensure transformation efficiency. Among various combinations analyzed, maximum transformation efficiency (20.8%) was attained with seeds of 5 min sonication combined with vacuum infiltration with 0.6 optical density of Agrobacterium culture. CONCLUSIONS: It concludes that a different Agrobacterium cell density with sonication combined with vacuum infiltration has improved transgenic efficiency in horse gram plants. This simple and efficient method is feasible for the stable expression of foreign genes that could be beneficial for future food security.