Isolation, identification of Phytophthora nicotianae var. parasitica and screening of tomato parental lines for buckeye rot resistance

Abstract

Buckeye rot disease of tomato which is one of the most devastating diseases of tomato crop is caused by soil born fungus Phytophthora nicotianae var. parasitica. In present study, the pathogen was isolated, morphologically identified and its pathogenicity was proved on susceptible commercial variety Solan Lalima and resistant line EC-251649 of tomato. Isolation of pathogen from the infected tomato fruit was achieved on Corn Meal Agar (CMA) out of two different media viz., Potato Dextrose Agar (PDA) and CMA. Fungal inoculum was prepared on Corn Meal broth. Inoculation with 10 ml of inoculum was found optimum in plant parts namely, stem, leaves and fruits. Parental lines were inoculated to test their disease reaction to buckeye rot. Symptoms of infection appeared on leaves and fruits only. Solan Lalima was found to be highly susceptible to with disease severity of 92 % and 100 % disease incidence, while EC-251649 was found moderately resistant on the basis of 16 % disease severity and 10 % disease incidence to the disease. After confirmation of resistance and susceptibility, the parental lines were surveyed for polymorphism using 42 primers and 32 were recorded to be polymorphic revealing that the differences are present at DNA level also. This is the very first study which evaluated parental lines for buckeye rot disease reaction on morphological as well as molecular basis. These lines will be further used for quantitative trait loci (QTL) analysis/gene tagging for buckeye rot and marker assisted selection to provide improved varieties to the farmers.