Elucidation of induced host plant resistance to white backed plant hopper (WBPH) in response to zinc application in rice

Abstract

Aim: The experiment was aimed to study the effects of various Zn formulations towards induced host plant resistance to WBPH in rice. Methodology: Eight zinc treatments comprising basal and foliar applications(at 30 and 45 DAT) of Zn SO4 and Zn-EDTA and their combinations were tested for induced host plant resistance to WBPH (a dreadful sucking insect) in a most sensitive rice variety TN 1. In addition, a treatment without any Zn application served as control. The pot grown plants were kept in the Mylar cages with top end covered by fine mesh muslin cloth and as such maintained till maturity. One adult gravid female insect was released into each cage (at 46DAT) and the insect population build-up was recorded after one month. Soluble protein profiling of leaf samples (at 60DAT) of each treatment was done by SDS-PAGE and data were analyzed for clustering pattern. Results: Altogether, 19 polypeptide bands (14.3-97.4kDa) were revealed. The low molecular weight proteins (14.3-25.1 kDa) were clearly absent in the control. T6(Zn EDTA at basal and foliar) recorded least WBPH build–up and elicited highest number (15) of polypeptide bands including five new bands at 66.0, 37.0, 23.6, 15.8 and 14.3 kDa. Further, 66.0kDa, 37.0 kDa and 14.3 kDa polypeptide bands were commonly shared by T6, T7(ZnSO4 basal+ EDTA foliar) and T8(Zn EDTA basal + ZnSO4) that recorded lower WBPH population and grouped together as compared to rest of the treatments and control. However, 23.6 kDa polypeptide band induced only in T6 and T7 seems to have greater role in manifestation of induced defence mechanism against WBPH in rice. Interpretation: The differentially expressed proteins (as compared to control) revealed in response to Zn application may be considered as biochemical basis of induced resistance for the pest in rice Key words: Induced resistance, Soluble protein profiling, White backed plant hopper, Zinc