Durable pest resistant grapevine rootstocks and germplasm evaluation
Summary
Objective
Effective safeguarding of vineyards from the spread of phylloxera and root knot nematode (RKN) requires new genetically diverse rootstocks with long-term resistance to these soil pests. Previous research programs at CSIRO have generated first-generation resistant rootstocks and tested them for suitability to Australian conditions. Four of the best (so-called C-series) rootstocks have been made available to the sector. In addition, further resistance genes were identified in wild Vitis species and hybrids, and provide the means to develop second-generation rootstocks with durable resistance to grape phylloxera and root knot nematode.
The objectives of this research project are to:
- continue the development of second-generation durable resistant rootstocks for Australian conditions
- identify and use new phylloxera and RKN resistance genes as the basis for development of third-generation durable resistant rootstocks
- develop second-generation, durable resistance, salinity-tolerant rootstocks from salinity-tolerant first-generation rootstocks and chosen parental breeding lines
- evaluate broad spectrum phylloxera resistance in key next-generation parental breeding lines (in collaboration with Agriculture Victoria)
- develop novel pest and salinity tolerant lines to improve CSIRO rootstock germplasm for future breeding
- maintain the CSIRO germplasm collection at Irymple and the first- and second-generation mildew resistant varieties generated in both current and previous projects.
Background
The two major soil pests that negatively impact Australian viticulture are phylloxera and root knot nematode (RKN). A significant decline in vine productivity (and even death) results from the feeding and reproduction of these pests on susceptible grapevines. The majority of Australian vineyards are maintained on own-rooted winegrape cultivars, Vitis vinifera, which is highly susceptible to these pests and makes them vulnerable to spread. Moreover, commercial rootstocks lack long-term resistance and have a narrow genetic base. In the event of a breakdown in phylloxera and/or RKN resistance, growers have limited options for replanting vineyards with alternative resistant rootstocks.
In addition to the challenges associated with pest resistance, a decrease in water availability due to a changing climate is expected to increase salinity levels in irrigated water. While grapevines are only moderately sensitive to salt exposure, uptake of chloride significantly reduces wine quality and represents a significant risk for an industry heavily reliant on irrigation. New, genetically diverse, climate resilient rootstocks with durable resistance to phylloxera and RKN, and that exclude chloride, are required to support the sustainability of the Australian wine grape industry into the future.
Research approach
The first objective of the project is to continue the development of second-generation, durable resistant rootstocks by crossing Vitis champinii (Ramsey) material with first-generation rootstocks. Seeds will be germinated using a modified embryo rescue method and marker-assisted selection used to detect phylloxera and RKN resistance genes in the progeny.
A similar approach will be used to incorporate gene(s) for chloride exclusion, to generate second-generation, durable resistant rootstocks that are also salinity-tolerant. We will also evaluate first generation rootstocks for chloride exclusion, to identify breeding lines that will be incorporated into our breeding scheme for managing production in regions that have salinity issues in the vineyard.
The third objective is to develop third-generation rootstocks harbouring a number of ‘stacked’ resistance genes and with Vitis candicans parentage. DNA markers linked to phylloxera and RKN resistance genes in V. candicans will be identified and used to select desirable progeny in crosses performed with first-generation rootstocks.
Parental breeding lines with all three phylloxera resistance genes will be evaluated for broad spectrum resistance by testing against phylloxera biotype-A and biotype-C genotypes in a collaboration with Agriculture Victoria. This will be done by propagating and sending parental breeding lines for phylloxera testing against the key phylloxera genotypes. In addition, a field trial will be established to evaluate the performance of selected first-generation rootstocks in a vineyard infested with diverse phylloxera genotypes.
Another objective is aimed at improving rootstock germplasm for future breeding. In this activity, crosses will be performed between Vitis species and hybrid material to create unique parental lines combining a variety of resistance loci with salinity tolerance. The resultant novel germplasm will be propagated and established at CSIRO Irymple Farm.
This project will also coordinate the maintenance and distribution of germplasm from the CSIRO grapevine variety collection at Irymple and the first- and second-generation mildew resistant grapevines generated in this and previous projects and located at Nuriootpa, Orange, Wagga Wagga and Irymple.
Sector benefits
The project will support research required to develop next generation, durable, pest-resistant and salinity-tolerant grapevine rootstocks and novel, genetically diverse rootstock breeding lines. These sustainable management tools will help to safeguard the Australian grape and wine sector from the spread of phylloxera and root knot nematode in a changing climate. The project will also coordinate the maintenance and distribution of germplasm from the CSIRO variety collection at Irymple, which has been closed to industry since 2009. A pipeline for distribution of first- and second-generation mildew-resistant grapevines will enable industry access to low-spray and no-spray grapevine varieties generated in previous and current grapevine breeding projects at CSIRO.