A single resistance factor to solve vineyard degeneration due to grapevine fanleaf virus.

Grapevine fanleaf disease, caused by grapevine fanleaf virus (GFLV), transmitted by the soil-borne nematode Xiphinema index, provokes severe symptoms and economic losses, threatening vineyards worldwide. As no effective solution exists so far to control grapevine fanleaf disease in an environmentally friendly way, we investigated the presence of resistance to GFLV in grapevine genetic resources. We discovered that the Riesling variety displays resistance to GFLV, although it is susceptible to X. index. This resistance is determined by a single recessive factor located on grapevine chromosome 1, which we have named rgflv1. The discovery of rgflv1 paves the way for the first effective and environmentally friendly solution to control grapevine fanleaf disease through the development of new GFLV-resistant grapevine rootstocks, which was hitherto an unthinkable prospect. Moreover, rgflv1 is putatively distinct from the virus susceptibility factors already described in plants.

French Jura flor yeasts: genotype and technological diversity.

Fifty-four Saccharomyces cerevisiae strains were isolated from Jura "Vin Jaune" velum and characterized by conventional physiological and molecular tests including ITS RFLP and sequence analysis, karyotyping and inter delta typing. ITS RFLP and sequence revealed a specific group of related strains different from the specific profile of Sherry flor yeast caused by a 24 bp deletion in the ITS1 region described by Esteve-Zarzoso et al. (Antonie Van Leeuwenhoek 85:151-158, 2004). Interdelta typing, the most discriminative method, revealed a high diversity of Jura flor yeast strains and gathered strains in clusters unequally shared between the northern and southern part of the Jura vineyard. The assessment of phenotypic diversity among the isolated strains was investigated for three wine metabolites (ethanal, acetic acid, and sotolon) from micro scale velum tests. Except at an early stage of ageing, the production of these metabolites was not correlated to the five genetic groups obtained by interdelta typing, but correlated to the cellar where strains had been isolated. The different strains isolated in a cellar produced mostly one type of velum (thin or thick, grey or white); but thin and grey velums, recognized as responsible for high quality wines, were obtained more frequently for one of the five groups of delta genotypes.