EVALUATION OF ANTISERUM RAISED AGAINST PESTALOTIOPSIS-THEAE FOR THE DETECTION OF GREY BLIGHT OF TEA BY ELISA

Polyclonal antiserum was raised against the mycelial extract of Pestal otiopsis them and immunoglobulin fractions were purified by ammonium s ulfate fractionation and chromatography on DEAE-Sephadex. In enzyme-li nked immunosorbent assay, antiserum dilution up to 1:16000 detected ho mologous antigen at a 5 mg/L concentration, and at 1:125 antiserum dil ution fungal antigens could be detected at a concentration as low as 2 5 mu g/L. In fifteen varieties of tea tested, originating from Darjeel ing, UPASI and Tocklai breeding stations, absorbance values of infecte d leaf extracts were significantly higher than those of healthy extrac ts at a concentration of 40 mg/L in indirect ELISA. ELISA-positive mat erial was detected in tea leaves as early as 12 h after inoculation wi th P. them. At antiserum dilutions up to 1:125, the pathogen could be detected in inoculated leaf extracts up to antigen concentration of 2 mg/L. The antiserum reacted with two other isolates of P. them tested but not with the antigens from mycelial extracts of Glomerella cingula ta and Corticium invisum or with extracts of tea leaves inoculated wit h these pathogens. The results demonstrate that ELISA can be used for early detection of P. them in leaf tissues even at a very low level of infection.