Histochemistry and anatomy of phylloxera (<i>Daktulosphaira vitifoliae</i>) nodosities on young roots of grapevine (<i>Vitis</i> spp).

Abstract

Phylloxera (Daktulosphaira vitifoliae FITCH) induce galls (nodosities) on young grapevine roots. Histological and histochemical methods were applied to study the gall's morphology and enzyme activities (peroxidases, leucine aminopeptidases and acidic phosphatases). Susceptible V. vinifera cv. Cabernet Sauvignon was compared to the resistant rootstock 5 BB (V. berlandieri x V. riparia) using aseptic dual culture conditions. The gall induction phase was analyzed before visible signs of potential resistance responses were detected. Elevated metabolic activity has been found in nodosities compared to uninfected roots. Starch granule incorporation was detected in young galls and was highest at the feeding site. As galls mature, the starch density decreased at the feeding site and increased towards the periphery of the gall. Peroxidase, acidic phosphatase and leucine aminopeptidase activities were highest at the incision. No differences in enzyme activities could be detected between the two cultivars tested.