College of Agricultural, Human, and Natural Resource Sciences

Department of Plant Pathology

Humphreys-Pereira Completes PhD Final Exam

Danny A. Danny Humphreys, PhD studentHumphreys-Pereira recently completed the requirements for his Ph.D. degree in plant pathology at Washington State University (WSU).  His dissertation was entitled “Genetic diversity and comparative mitochondrial genomics of root-knot nematodes (Meloidogyne spp.).”  His committee included Tobin L. Peever (Chair for one year), Axel A. Elling (Chair for four years), Jeremiah W. Busch, Timothy D. Murray, and Timothy C. Paulitz.  He characterized four types of M. chitwoodi using light and scanning electron microscopy, isozyme analysis, and molecular markers.  He described a new Meloidogyne species associated with coffee in southern Costa Rica, and developed a PCR-RFLP system to differentiate coffee-parasitizing Meloidogyne species.  Through mitochondrial genome sequencing and comparison, he obtained data supporting the hypothesis that the migratory endoparasitic nematode genus Pratylenchus shares a recent common ancestor with Meloidogyne.  His results also suggested that the sedentary endoparasitic nematodes, Meloidogyne and Heterodera, evolved through convergent evolution.  Humphreys-Pereira grew up in the Caribbean coast of Costa Rica, and received his B.S. degree in biotechnology engineering from Tecnológico de Costa Rica in 2005 and M.S. degree in crop protection from University of Costa Rica in 2010.  He came to WSU in 2010 with a Fulbright Ph.D. fellowship.  He received Cobb Student Travel awards to attend the Society of Nematologists meetings in 2012 and 2015, and WSU Richard R. and Constance M. Albrecht award in 2015.  He will work at the University of Costa Rica to teach “Introduction to nematology” and “Management of nematodes.”

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