Grapevine genes for improved resistance to fungal pathogens to reduce chemical inputs in Australian vineyards

Abstract

This project has successfully cloned the powdery mildew resistance (Run1) and downy mildew resistance (Rpv1) genes from the wild North American grapevine Muscadinia rotundifolia.
Introduction of these resistance genes into susceptible winegrape cultivars by genetic
transformation produces transgenic vines with strong resistance to these fungal pathogens in laboratory-based assays.

Summary

Powdery mildew caused by Erysiphe necator (syn. Uncinula necator) and downy mildew caused by Plasmopora viticola are the two most economically important grapevine diseases worldwide. Genetic resistance to powdery and downy mildew has been identified in many crop species, but the winegrape species Vitis vinifera displays no inherent resistance to these fungal pathogens. As a result, control of these diseases is entirely dependent on the widespread application of fungicides. It has recently been estimated that costs of disease management and yield losses to the Australian Wine Industry are of the order of 76 and 63 million AUD per year for powdery mildew and downy mildew respectively. There is also increasing world-wide pressure to reduce agrochemical use for the control plant pathogens on crops grown for human consumption. These problems could be overcome by the development of grapevine cultivars with enhanced genetic resistance to powdery and downy mildew.

In a previous GWRDC-funded CRCV project (CRV 99/14a), good progress was made towards the genetic mapping and sequencing of the Run1 (resistance to Uncinula necator) / Rpv1 (resistance to Plasmopora viticola) locus from the wild North American grapevine Muscadinia rotundifolia. That project identified four full-length resistance gene analog (RGAs), which show a high degree of similarity to fungal resistance genes isolated from other crop species.  However, sequencing of certain regions of the Run1/Rpv1 locus remained incomplete and evidence indicated that other RGA sequences were present.