Age as a factor in induction of systemic acquired resistance in tomato against bacterial speck by aqueous fruit extracts of Azadirachta indica

In the present study, the effect of aqueous fruit extracts of Azadirachta indica on activity of Peroxidase (POX) at different ages of Tomato (Lycopersicon esculentum) leading to induction of systemic resistance against Pseudomonas syringae pv. tomato was evaluated. For this evaluation, four ages, that is, 6, 8, 10 and 12?weeks of plants were selected. A single leaf at the third node from base of each plant was treated either singly or with different combinations of Neem extract and pathogen. Samples were collected at an interval of 24?h for up to five days and after two weeks of the treatment from both treated and untreated nodes. The change in the activity of defence enzyme POX and expression of its isoforms was studied. The results demonstrate that systemic acquired resistance induced by the Neem fruit extract increases as the plant matures but it is not only the limiting factor.