Screening for resistance to ripe rot caused by Colletotrichum acutatum in grape germplasm

We screened 235 Vitis and six Muscadinia grapevine cultivars and selections conserved at the National Institute of Fruit Tree Science in Japan for resistance to grape ripe rot, caused by Colletotrichum acutatum Simmonds ex Simmonds. This fungus is insensitive to fungicides such as benomyl, diethofencarb, and iminoctadine-triacetate. We evaluated the disease resistance of nearly ripe berries from each cultivar and selection by artificial inoculation with C. acutatum. Analysis of variance of 20 cultivars and selections indicated that the genotype had a significant effect but that the year had no significant effect on the percentage of diseased berries. Genetic variance explained 85 % of total variance. Each cultivar or selection was classified into one of the following four classes based on its level of resistance to ripe rot: 50 highly resistant (≤ 20 % affected), 37 resistant (21- 40 %), 48 susceptible (41- 60 %), and 106 highly susceptible (≥ 61 %). Of the highly resistant cultivars and selections, we consider a diploid named 676-64 to be promising material for ripe rot resistant table grape breeding.

Transcriptome profiling on the response of Mycosphaerella graminicola isolates to an azole fungicide using cDNA arrays

Resistance to azole antifungals is a major problem in the control of diseases caused by fungal pathogens of both humans and plants. Potential for the development of azole resistance in the wheat leaf blotch pathogen Mycosphaerella graminicola, the causal agent of the most economically significant foliar disease of wheat in north-western Europe, is now of particular concern after the recent emergence of widespread resistance to quinone outside inhibitor fungicides. Using a cDNA microarray representing around 25% of the genome, we have profiled the transcriptional response of M. graminicola to epoxiconazole, currently the most widely used azole fungicide on cereal crops. By comparing the transcription profiles of two M. graminicola isolates with contrasting sensitivities to epoxiconazole we show qualitative and quantitative differences in differentially expressed genes, including those involved in ergosterol biosynthesis, mitochondrial respiration and transport mechanisms. This represents the first study investigating the response of a plant pathogenic fungus to a fungicide using cDNA microarray technology