Activity of Pectinases in Conidia and Germlings of Blumeria graminis and the Expression of Genes Encoding Pectinases.

Abstract

The production of pectinases and the expression of genes encoding pectinases by conidia and germlings of Blumeria graminis f. sp. tritici were investigated. By pectate plate assay, the activity of polygalacturonase was detected in homogenates from ungerminated conidia and germlings grown on an artificial substratum. We could amplify the fragments of two endo-polygalacturonase genes, two pectin lyase genes and a pectate lyase gene from genomic DNA of the fungus by the polymerase chain reaction (PCR). The genes were designated as pg1 and pg2, pnl1 and pnl2, and pel1, respectively. Their nucleotide sequences and the deduced amino acid sequences of their fragments showed high homology to those of the reported sequences of corresponding pectinases of other fungi. The RT-PCR indicated the expression of pg1, pg2 and pnl2 in ungerminated conidia and germlings. The expression of pnl1 and pel1 was detected only at the late stage of the infection in wheat leaves but not in ungerminated conidia and germlings on an artificial substratum and at an early stage of infection in wheat leaves. The present results suggested possible involvement of pg1, pg2, pnl1, pnl2 and pel1 in morphogenesis and/or pathogenesis of this fungus.