Silencing of cellulose synthase genes of Phytophthora infestans for conferring late blight resistance in Indian potato Solanum tuberosum L cultivars

Abstract

Late blight is the most devastating disease of potatoes, which is caused by an oomycete Phytophthora infestans. The disease is known to cause significant crop losses each year. Many efforts have been made for the effective management of the late blight but the rapid development of new strains of P. infestans is the major constraint. The applicability of host- induced gene silencing (HIGS) in many plants against their pathogen has proven an effective approach and has driven the attention of many researchers. Therefore, in the present study, HIGS approach was adopted to silence the cellulose synthase (CesA) gene(s) of P. infestans to achieve late blight resistance in selected potato cultivars. In the present study, two important potato cvs. Kufri Pukhraj and Kufri Chipsona 1 were selected based on their resistance to late blight disease. The evaluation assay of four Indian potato cultivars (Kufri Pukhraj , Kufri Chipsona 1 , Kufri Jyoti and Kufri Surya ) with the sporal suspension of P. infestans revealed that the cvs. Kufri Pukhraj (93.75% DI; 85.41% DS) is susceptible, Kufri Chipsona 1 (75% DI; 59.83% DS), Kufri Jyoti (68.75% DI; 56.25% DS) is moderately resistance and Kufri Surya (18.75% DI; 3.46% DS) is resistant to late blight. Therefore, the two cultivars Kufri Pukhraj and Kufri Chipsona 1 were selected for transformation with the Agrobacterium harbouring hp-RNAi constructs specific to the CesA genes of P. infestans. The process of Agrobacterium-mediated genetic transformation requires the optimisation of regeneration protocol as difficulties are faced in shoot organogenesis on selection-cum regeneration medium after co-cultivation. Therefore, in this study the effect of and#946;-lactam antibiotics (used for elimination of Agrobacterium) and sucrose was investigated to improve shoot organogenesis. The effect of and#946;-lactam antibiotics viz. cefotaxime, carbenicillin, and cephalexin was studied on shoot regeneration of potato cvs. Kufri Pukhraj and Kufri Chipsona 1 . Leaf and internodal explants