Post-infectional changes associated with the progression of leaf spot disease in Calotropis procera Aiton

The present work was designed to study the post-infectional alterations associated with the disease progression during leaf spot disease caused by Passalora calotropidis in Calotropis procera. It is an important medicinal plant of family Apocynaceae and subfamily Asclepiadaceae. In the present work, various parameters such as leaf area, number of leaf spots, biochemical parameters, i.e., total chlorophyll content, total protein content, and anti-oxidative enzyme activities, i.e., catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) were studied to assess the post-infectional changes associated with the disease progression. Various organic acids, i.e., malic acid (MA), succinic acid (SA), citric acid (CA) and fumaric acid (FA) were also analyzed by using GC-MS. It was found that total chlorophyll and total protein contents decreased in disease severity level 1 (DS1), DS2, DS3, DS4 and DS5 significantly as compared to the healthy plant (DS0). The results of antioxidant enzymes indicate that the activities of CAT, APX and GPX were increased in disease progressed leaves as compared to the healthy plant leaves. Similarly trend was found for CA. The present study suggested a complicated basis of post infectional changes, the facts obtained is helpful for better interpretation of host pathogen interaction.