Peroxidase activity as a marker to evaluate resistance in Black pepper against Phytophthora infection

Foot rot caused by Phytophthora capsici / P. tropicalis , is the most deleterious of all diseases affecting black pepper. Conventional pathogen inoculation and response to biochemical parameters such as lignin and peroxidase activity were targeted for locating source of resistance in black pepper. The direct response of infection as phenotypic symptoms and defense response imparted by lignin and peroxidase activity was studied in eight black pepper varieties, namely 04-P24, IISR Shakthi, Sreekara, Panniyur-1, Malabar Excel, Thevam, Panchami, Pournami and four germplasm accessions (7731, 7583, 8041, 8062) that showed differential response to Phytophthora infection. Among the varieties tested, 04-P24 showed no symptoms of infection and found as resistant. The response of lignin and peroxidase activity upon infection showed 04-P24 as having highest peroxidase activity with higher lignin content. Based on consecutive results, it is inferred that increased levels of lignin and peroxidase contributed to development of Phytophthora resistance in black pepper. The study suggests that peroxidase activity can be used as a biochemical marker for screening black pepper plants for Phytophthora resistance.