Morphological and Biochemical Characterization of Phaeoisariopsis personata Resistant and Susceptible Cultivars of Groundnut (Arachis hypogaea)

Abstract

Thirteen groundnut (Arachis hypogaea) cultivars were screened for resistance to Phaeoisariopsis personata under natural conditions. They were classified into resistant (cultivar FDRS-10), moderately resistant (cultivars K-134, TCGS-156 and Tpt-3) and susceptible (Tpt-1, Tpt-2, TCGS-29, TCGS-91, TCGS150, TCGS-341, Tpt-4 JL-24 and TMV-2), based on a disease severity of 1-9 scale. Morphological characters namely stomatal frequency and size, biochemical parameters namely chlorophyll, total phenols, peroxidase and polyphenol oxidase were estimated among the cultivars having different degree of resistance. The stomatal frequency and size was less in resistant cultivar, FDRS-10 and more in susceptible cultivar, TMV-2. The chlorophyll content was highest in resistant cultivar, which decreased upon infection in all cultivars. Total phenols, peroxidase and polyphenol oxidase were higher in resistant cultivar, FDRS-10 and upon infection, increased further, in all cultivars under study. Significant differences in banding profiles of phosphatase and esterase isozymes were observed in all cultivars. One phosphatase band at Em of 0.07 and two esterase bands at Em of 0.50 and 0.63 were specific to resistant cultivar, FDRS-l0 only. The detected isozyme variability could possibly be used as biochemical marker in identification of Phaeoisariopsis personata resistant cultivars of groundnut.