Elicitation of Phytoalexins against Late Blight Disease in Tomato Plants by Abiotic Agents and its Impact on Disease Resistance

Abstract

Tomato is one of the world's major vegetable crops. Like other important crops, tomatoes also suffer huge crop losses due to many diseases. Among these diseases, late blight caused by Phytophthora infestans. The present study was conducted to induce defence reaction in tomato plants against late blight disease under field conditions using some abiotic agents. Tomato plants sprayed by ethyl salicylic acid (2.5 ml/20 litre water) resulted in lowering disease incidence to great extent( from 25±1.41% in control plants to 1.66±1.03%), followed by coconut milk solution (1%) and Agrispon® (1%). These three agents were found to induce accumulation of sesquiterpenoid stress metabolites (phytoalexins) in tomato fruits when they were tested for its elicitation capability. Rishitin, lubimin, phytoberin and unknown compound were detected in tomato fruit diffusates treated by abiotic agents. This is the first record that these agents elicit phytoalexins in tomato fruits.