New insights into pathogenicity of emerging tropical plant pathogens: genomics and transcriptomics of Phytophthora colocasiae on taro

Phytophthora colocasiae is a phytopathogenic oomycete that causes leaf blight, and corm rot, on taro (Colocasia esculenta). Taro is an important staple crop in the tropics, and the emergence of P. colocasiae as a devastating pathogen is a matter of serious concern for food security in the region, since many of the Asian and Oceanic cultures heavily rely on taro to maintain their daily calorific intake. P. colocasiae strain 7290 was isolated from a diseased taro plant in Vietnam in 2010 and is primarily triploid. The draft genome of P. colocasiae strain 7290 is 56.59 Mb. It contains 19,984 predicted genes. Phytophthora species secrete a large arsenal of effectors during infection of their host plants and genome mining along with transcriptome analysis of taro-P. colocasiae interactions has identified a number of putative Carbohydrate active enzymes, Peptidases, secretory proteins (1782) including cytoplasmic effectors such as RxLR (337) and CRN family members (203), as well as novel effectors that specifically target taro. The genome and transcriptome analysis of P. colocasiae is a first step towards understanding pathogenicity determinants, in this pathogen and to design specific management strategies to control the disease. Tropical plant pathogenic oomycetes are not well studied, and our data provides insights into the development of disease within such a climate A detailed comparative genomics analysis of the genomes of this and other closely or distantly related plant pathogenic oomycetes and fungi will allow us to elucidate the precise genetic components of pathogenicity in P. colocaisae, and uncover the evolution of pathogenicity in this unique tropical species. Our latest analysis of the genome and transcriptome data, including discovery of putative novel effector proteins will be discussed.