Search of physiological and molecular markers for grapevine tolerance to fungi-induced wood decay diseases

A possible strategy to cope with grapevine wood-decay diseases involves the selection of new cultivars or clones more tolerant to fungal pathogens responsible for these pathologies. Such a selection implies to find simple and relevant selection criterions, linked to physiological and/or molecular responses of the plant to fungal infection; and correlated with wood-decay disease tolerance. In order to point out such criterions, a better understanding of grapevine/wood-decay causing agents interaction is needed. Therefore, a three year project, starting in January 2010 will compare the molecular and physiological responses of four grapevine genotypes ('Ugni blanc', 'Cabernet sauvignon', 'Merlot' and Muscadinia) to the infection of the ascomycete Eutypa lata, the causal agent of Eutypa dieback. For each genotype, artificially infected and non-infected batches of wood cuttings will be compared for: (i) wood necrosis progression, (ii) foliar symptom expression, (iii) physiological parameters (photosynthesis, transpiration rates, gas exchanges) and (iv) gene expression using genome-wide Combimatrix+ microarrays both in foliage and wood. Correlation analysis of the measured physiological parameters, specific gene expression, necrotic progression and symptom expression in the different genotypes will help to identify potential tolerance markers. Furthermore, preliminary work with three Botryosphaeriaceae species will also be performed, but on a smaller scale (necrosis analysis, symptom expression, candidate gene expression by RT-qPCR) in order to investigate whether genotypes more tolerant to E. lata are also more tolerant to the Botryosphaeriaceae.