Use of ELISA to Quantify Magnaporthe grisea in a Rice Leaf

Abstract

We produced a polyclonal antibody which reacts with antigens of mycelia of the rice blast fungus. Using this antibody, we developed an ELISA method which can measure small amounts of mycelia of Magnaporthe grisea (Hebert) Barr in a rice leaf. More than 0.1μg mycelia of the rice blast fungus in 100mg of fresh leaf can be measured by this method. The antibody, acquired using lyophilized mycelia of the fungus, reacts as well with fresh mycelia, conidia, and even those of different races as it does with lyophilized ones. But it does not react with mycelia of several fungal pathogens of the rice plant. Thanatephorus cucumeris (Frank) Donk, Rhizoctonia sp., Cochliobolus miyabeanus (Ito et Kuribayashi) Drechsler ex Dastur, Sphaerulina oryzina Hara and Nigrospora oryzae (Berkeley et Broome) Petch do not react with the antibody at 20μg dry weight mycelia/ml of PBS (pH 7.5) containing 0.05% Tween 80. But at about 2mg/ml, the antibody slightly reacts with mycelia of Sphaerulina oryzina and Nigrospora oryzae. This method should be useful in understanding the interaction between blast fungus and rice plant.