Early detection of epiphytic anthracnose inoculum on phyllosphere of Diospyros kaki var. domestica

Abstract

We developed a polyclonal antibody (PAb) based-ELISA system to accurately and rapidly monitor inocula on plant surface before onset of anthracnose. Titer of mouse antisera against conidia of Colletotrichum gloeosporioides was determined by using indirect ELISA. It was high enough to be detectable up to × 12,800 dilutions. Absorbance readings exceeded 0.5 even at a 10-5 dilution. Sensitivity of PAb was precise enough to detect spore concentration as low as 50 conidia/well by indirect ELISA. PAb1 and PAb2 proved to be very sensitive and highly specific to the target pathogen, C. gloeosporioides, apparently discriminating other unrelated pathogens, or epiphytes. Absorbance values for original isolate exceeded 1.0, but no reaction was detected with other isolates, except three other anthracnose fungi: C. gloeosporioides (pepper strain), Glomerella cingulata (apple strain) and C. lagenarium. Our data suggest that PAb1 and PAb2 bind with the protein epitope that partially contains residues of amino acid, arginine, and lysine. This kit fulfills the requirements for detecting inoculums before infection and during onset of anthracnose on sweet persimmon.