Scion genetics & improvement: development of new disease-resistance varieties

The aim of this project is to breed second generation mildew-resistant scions combining powdery mildew and downy mildew resistance genes from different wild genotypes to further enhance the durability of these new selections in the vineyard. The project will carry out crosses between V. vinifera microvine progeny containing new resistance loci for powdery and downy mildew (derived from wild Chinese Vitis species) with selected first-generation disease-resistant progeny containing Run1 and Rpv1. The resultant seed will be screened at the seedling stage, using DNA markers, to identify progeny that will produce perfect flowers (fruit) and that carry two powdery mildew and two downy mildew resistance loci. These plants will be transferred to the field and screened over many seasons for vine performance including yield and fruit (wine) quality. The next stage will be to develop microvine breeding lines containing two powdery mildew and two downy mildew resistance genes in the homozygous state. Having all four resistance loci in the homozygous state in one of the parental lines will ensure that all progeny generated using this parent will contain all four resistance loci and allow selection for progeny containing desirable consumer traits.