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Poster: Biology & Disease Mgmt: Oomycetes


Phylogenetic relationships among Philippine isolates of Peronosclerospora based on sequence analysis of multiple mitochondrial loci
F. DELA CUEVA (1), M. Samaco (1), M. Ramon (2), F. Martin (2) (1) Institute of Plant Breeding, University of the Philippines Los BaƱos, Philippines; (2) USDA ARS, U.S.A.

Downy mildews cause substantial yield losses of sugarcane and corn in the Philippines with several species of Peronosclerospora (P. sacchari, P. spontanea, P. miscanthi, and P. philippinensis) commonly reported. Due to the obligate nature of the pathogen only spore morphology and host genus have been used as the bases of species identification. However, these parameters are highly effected by environmental conditions. Therefore, molecular tools are needed for investigating pathogen diversity and taxonomy. Primers have been developed for amplification of three mitochondrial loci from fifty-four isolates of Peronosclerospora recovered primarily from sugarcane representing geographically diverse regions in the Philippines. Limited sequence divergence of the mitochondrial loci was observed among these isolates. Additional isolates recovered from corn are being sequenced and added to the analysis to evaluate the taxonomy and phylogenetic relationships among corn and sugarcane downy mildews. Studies involving a broad sampling of the pathogen from other grasses in the Philippines and neighboring Asian countries are being conducted to assess the diversity and identify species of tropical graminicolous downy mildews. To facilitate rapid pathogen identification, species-specific molecular diagnostic assays targeting mitochondrial loci are under development. This is especially important for detection of the USDA-APHIS Select Agent P. philippinensis.