I am a PhD student at Plant Research International (PRI), Wageningen University and Research Centrum in The Netherlands. PRI is co-developing DArT with DArT P/L. After obtaining a proof-of-concept that DArT can be used as an efficient and accurate marker technology in Arabidopsis thaliana (Wittenberg et al., 274: 30-39), PRI has applied DArT successfully in some other species.

Currently I am working at DArT P/L on the construction of a high-density genetic linkage map of Mycosphaerella graminicola for genomics of pathogenesis, using DArT technology.

Mycosphaerella is one of the largest genera of plant pathogenic fungi, having more than 1,000 named species, many of which cause economically important diseases in temperate and tropical crops. M. graminicola (asexual stage: Septoria tritici), is the cause of Septoria tritici blotch, one of the most common and important diseases of wheat worldwide. The estimated annual cost of fungicides applied against Septoria tritici blotch in Europe is ~$400 million -approximately 70% of the total fungicide input in cereals in that region. Isolates of M. graminicola exhibit two types of host specificity: cultivar specificity and species specificity. Cultivar specificity refers to virulences and avirulences to specific cultivars of either bread wheat or durum wheat, whereas species specificity refers to avirulences to all bread wheat or durum wheat cultivars (see figure).

Source: Sarah Ware

The development of a high-density genetic DArT linkage map will enable us to:

• Map pathogenicity factors. Phenotyping of the segregating population regarding pathogenicity and virulence is currently used for this purpose;
• Map series of genes from the large EST databases, and check which genes are located in the QTL for pathogenicity and other important traits;
• Clone genes using a map-based cloning strategy;
• Integrate DArT markers into an existing map from two Dutch field isolates (Kema et al., 2002);
• Order contigs generated in the whole genome shotgun sequencing project of M. graminicola currently performed by the Joint Genome Institute.

Construction of this high-density map is critical for boosting the genomics research in M. graminicola and other Mycosphearella species such as M. fijiensis in banana. DArT is the marker method of choice for constructing such a map, because of the high data quality it generates and the ease by which markers can be sequenced.

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