Expression of Cry2Aa, a Bacillus thuringiensis insecticidal protein in transgenic pigeon pea confers resistance to gram pod borer, Helicoverpa armigera

Pigeon pea is an important legume infested by a plethora of insect pests amongst which gram pod borer Helicoverpa armigera is very prominent. Imparting resistance to this insect herbivore is of global importance in attaining food security. Expression of insecticidal crystal proteins (ICP) in diverse crops has led to increased resistance to several pests. We report in this paper, expression of Cry2Aa in transgenic pigeon pea and its effectiveness towards H. armigera by employing Agrobacterium-mediated in planta transformation approach. Approximately 0.8% of T-1 generation plants were identified as putative transformants based on screening in the presence of 70 ppm kanamycin as the selection agent. Promising events were further recognized in advanced generations based on integration, expression and bioefficacy of the transgenes. Seven T-3 lines (11.8% of the selected T1 events) were categorized as superior as these events demonstrated 80-100% mortality of the challenged larvae and improved ability to prevent damage caused by the larvae. The selected transgenic plants accumulated Cry2Aa in the range of 25-80 mu g/g FW. The transgenic events developed in the study can be used in pigeon pea improvement programmes for pod borer resistance.