Grape rot is one of the major causes of degradation of many grape components and, thus, of deterioration in wine quality. In particular, the association of Botrytis cinerea with other, less visible, fungi frequently leads to the development of organoleptic defects in grapes and sometimes in wines. This study examines the nature of the volatile compounds responsible for mushroom, mossy, or earthy odors detected by gas chromatography-olfactometry in organic extracts of rotten grapes and musts. 2-Methylisoborneol, (-)-geosmin, 1-octen-3-one, 1-octen-3-ol, 2-octen-1-ol, and 2-heptanol were identified or tentatively identified. Their concentrations in musts were determined, and the impact of alcoholic fermentation by the yeast Saccharomyces cerevisiae was studied. The ability of fungi isolated from rotten grapes (Botrytis cinerea; Penicillium species including P. brevicompactum, P. expansum, P. miczynskii, P. pinophilum, P. purpurogenum, and P. thomii; Aspergillus section nigri; Rhizopus nigricans; and Coniothyrium sp.) to produce some of the identified compounds was evidenced.
A first comprehensive inventory of alien fungi and fungal-like organisms (in Stramenopila) recorded in France since 1800 was established, comprising 227 species, with 64.7% plant pathogens, 29.5% saprotrophic species, 3.5% ectomycorrhizal fungi, 1.3% animal parasites and 0.9% mycopathogenic fungi. Using this and a previously built European dataset, correlates of invasion success in fungi (sensu lato) were investigated, especially for pathogenic species occurring in wild environments (mostly forest tree pathogens). Several common features were demonstrated at the two spatial scales. Some taxonomic/phylogenetic orders were shown to be over-represented in alien fungi and Stramenopila pseudo-fungi, e.g. Peronosporales and to have faster spread, e.g. Erysiphales. Residence time and economic variables, especially imports, were important explaining variables of the levels of invasion. The influence of climatic factors was also suggested.
WRKY genes encode proteins belonging to a large family of transcription factors that are involved in various developmental and physiological processes and in plant responses to pathogen infections. In the present work, a full-length cDNA from a Vitis vinifera L. cv. Cabernet Sauvignon grape berry library was isolated and characterized. The cDNA, designated VvWRKY2, encodes a polypeptide of 536 amino acids that shows the structural features of group I of WRKY protein family. VvWRKY2 is expressed in the different organs of healthy grapevine plants. In leaves, VvWRKY2 is induced by wounding and after infection with Plasmopara viticola. Constitutive expression of VvWRKY2 in tobacco reduced the susceptibility of transgenic tobacco to three types of fungal pathogens infecting different parts of the plant: Botrytis cinerea (leaves), Pythium spp. (roots) and Alternaria tenuis (seeds). The results indicate that VvWRKY2 may be involved in the resistance of grapevine against the pathogens.
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