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Pasture Improvement Initiative

New project to boost sub-clover disease resistance

A new Rural Industries Research and Development Corporation (RIRDC) funded project could see significant increases in sub-clover production through better disease resistance in future cultivars of the popular annual pasture legume.

Soil-borne root rot pathogens can cause seedling losses of more than 90% in sub-clover pasture stands. This has a major impact on both seed-production stands and grazing paddocks, through weed competition, weaker root systems and reduced biomass and seed production.

Seed-production stands also are particularly vulnerable to yield losses by fungal foliar diseases. Breeding disease-resistant cultivars is the most economic means of combating disease. However, little is known about the genetics and diversity for resistance to the four most important diseases of sub-clover.

In a world first, the new project will identify new genes and quantitative trait loci (QTL) for resistances to the most important foliar and root rot diseases of sub-clover and deliver molecular markers closely linked to them for use in future breeding programs.

The initial stages of the project will see researchers phenotype the 97-member sub-clover core collection, which represents about 80% of the genetic diversity within the species, and 28 diverse sub-clover cultivars for reactions to the foliage diseases clover scorch (Kabatiella) (to both races 1 and 3 and for both seedling and adult plant resistance) and rust, (Uromyces) and to the root rot pathogens Pythium and Phytophthora.

The second stage of the project will involve identifying molecular markers closely associated with genes and QTL for resistance to each of these four diseases. The project outcomes will allow sub-clover breeding programs to simultaneously select genotypes with genes for multiple disease resistance and other desirable traits.

Dr Martin Barbetti, Professor in Plant Pathology and Mycology at The University of Western Australia (UWA) will lead the project. Co-researchers include Dr Phillip Nichols, a Senior Pasture Scientist with the Department of Agriculture and Food Western Australia (DAFWA); Professor William Erskine, Director of the Centre for Plant Genetics and Breeding at UWA; and Dr Parwinder Kaur from UWA.

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