Why Sequence Mycosphaerella?

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. A few species of Mycosphaerella cause disease in humans and other vertebrates, so the genus is of interest both for human and plant health. Two species will be sequenced: M. graminicola (asexual stage: Septoria tritici), the cause of Septoria tritici blotch, one of the most common and important diseases of wheat worldwide; and M. fijiensis, the cause of black sigatoka, the most economically significant disease in banana plants. Losses caused by M. graminicola cost United States wheat growers more than $275 million every year. 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. Infection is very severe in Mediterranean and East African countries, such as the highlands in Ethiopia, and likely significantly reduces yields of the world’s most widely planted food crop. Its genetic tractability, availability of extensive genomic resources, large worldwide research community, and phylogenetic distinctiveness from other fungi being sequenced make M. graminicola a major target for the life sciences.

In a wider perspective, the genus Mycosphaerella contains at least 10,000 species, making it the largest genus of plant pathogens. It causes extensive economic losses on a range of crops including tomatoes, strawberries, sugar beets, soybeans, and even tree crops. Comparison of two species in the same genus will facilitate gene annotation, reveal which genes are specific to each pathogen, and identify genes involved in pathogenicity in general. This research will yield scientifically novel results because species in the genus Mycosphaerella are phylogenetically distinct and have a different mechanism of pathogenicity from other plant pathogens with sequenced genomes. This information will have global impact on Mycosphaerella research and will further develop M. graminicola as a model for fungi in the order Dothideales. Sequencing representatives of this ecologically significant order will greatly increase the biodiversity represented among sequenced organisms and will facilitate a global understanding of pathogenicity through comparative genomic analyses. These advances should eventually result in environmentally sound strategies to control several globally important diseases.

CSP project participants: Stephen B. Goodwin (proposer) and Gert H.J. Kema (USDA-ARS and Purdue Univ.).