Temperature Mediated Interactions between the Aggressiveness of Phytophthoradrechsleri f. sp. Cajani and Activity of Defense Enzymes in PigeonpeaGSenthilrajaauthorCJyothi ReddyauthorSPandeauthorMSharmaauthorA pigeonpea field survey was conducted during the year 2010–2013 in the semi-arid tropics of India (Andhra Pradesh, Karnataka and Maharashtra), where the temperature is usually high. Phytophthora blight (PB) of pigeonpea caused by Phytophthoradrechslerif.sp. cajani (Pdc) was widespread in all the surveyed areas irrespective of cultivars sown and disease incidence varied between 5–60%.Therefore, the objective of the study was to study the effect of range of temperatures (15–40 °C) on the PB development and on the activity of plant defense enzymes. Under controlled environment studies, we found that disease appeared in all the temperatures with varied incubation period (IP). At higher temperatures (30, 35 and 40 °C), IP was 32, 26 and 18 hours, however at 25, 20 and 15 °C, disease was delayed with an IP of 63, 126 and 225 hours, respectively. To further understand the host, pathogen and environment interactions, biochemical analysis of defense enzymes viz., phenylalanine ammonia lyase, peroxidase, polyphenoloxidase and catalase was studied at all temperatures after 0, 24, 48, 72 and 96 hours of inoculation. Activity of defense enzymes in inoculated plants increased progressively at temperatures 25–40 °C during the infection process and then a decline was noticed after the disease progressed. However, at lower temperatures, significant difference was not found in inoculated and uninoculated plants. This study depicts the aggressiveness of Pdcat higher temperatures and will be useful in further strengthening the crop protection practices to mitigate the effect of climate change on plant diseases.Pigeonpea2013-12Conference or Workshop Item