Overexpression of a chitinase gene in transgenic peanut confers enhanced resistance to major soil borne and foliar fungal pathogens

A chitinase gene from rice (Rchit) was introduced into three varieties of peanut through Agrobacterium-mediated genetic transformation resulting in 30 transgenic events harboring the Rchit gene. Stable integration and expression of the transgenes were confirmed using PCR, RT-PCR and Southern blot analysis. Progeny derived from selfing of the primary transgenic events revealed a Mendelian inheritance pattern (3:1) for the transgenes. The chitinase activity in the leaves of the transgenic events was 2 to 14-fold greater than that in the non-transformed control plants. Seeds of most transgenic events showed 0-10 % A. flavus infection during in vitro seed inoculation bioassays. Transgenic peanut plants evaluated for resistance against late leaf spot (LLS) and rust using detached leaf assays showed longer incubation, latent period and lower infection frequencies when compared to their non-transformed counterparts. A significant negative correlation existed between the chitinase activity and the frequency of infection to the three tested pathogens. Three progenies from two transgenic events displayed significantly higher disease resistance for LLS, rust and A. flavus infection and are being advanced for further evaluations under confined field conditions to confirm as sources to develop peanut varieties with enhanced resistance to these fungal pathogens.