Molecular and genetic strategies to reduce the susceptibility of wine grapes to fungal pathogens

Abstract

Functional characterisation of transgenic winegrape varieties containing the MrRUN1 powdery mildew resistance gene and the MrRPV1 downy mildew gene from M. rotundifolia demonstrated that these genes confer strong resistance to mildew isolates from Australia, Europe and North America. However, a powdery mildew isolate from SE USA was identified which can break MrRUN1 resistance. New sources of genetic resistance to powdery and downy mildew from other North American and Chinese Vitis species were identified which could ultimately be combined with MrRUN1 and MrRPV1, in the same grapevine variety, to enhance the durability of this resistance in the vineyard.

Summary

Powdery mildew caused by the fungus Erysiphe necator (syn. Uncinula necator) and downy mildew caused by the oomycete Plasmopora viticola are the two most economically important grapevine diseases worldwide. The cultivated winegrape species, Vitis vinifera, has little or no genetic resistance to these pathogens. As a result, control of these diseases is entirely dependent on the widespread application of fungicides. Schofield and Morison (2010) estimated that costs of powdery mildew and downy mildew disease management and yield losses to the Australian Wine Industry are of the order of 76 and 63 million AUD per year, respectively. There is also increasing world-wide pressure to reduce agrochemical use for the control of plant pathogens on crops grown for human consumption.