Faculty Advisor

Elliott, Joel

Area of Study

Science and Mathematics

Publication Date

Summer 2019


A diverse range of marine organisms relies on seagrass as a foundational species. However, seagrass populations are declining at an alarming rate and recent analysis of seagrass root microbiomes indicates that oomycetes (fungi-like protists that are notorious terrestrial plant pathogens) infect up to 99% of seagrasses worldwide. Shockingly, very little is known about marine oomycetes and their ecological roles. The Elliott lab has isolated and cultured six oomycete species from eelgrass (Zostera marina) root samples: Phytophthora gemini, aHalophytophthoraspecies discovered by WSU, and four undescribed oomycete species. During the summer of 2018, I generated temperature and salinity growth curves and isolated genomic DNA for three of the five unknown species. During the summer of 2019, I generated sequence data for each isolate and constructed a molecular phylogeny based on each isolate’s rps10 and COX1 sequences. Phylogenetic analysis indicates that the undescribed isolates are significantly different from other known taxa and are in clade with other Halophytophthora, Pythium, and Phytopythium species. Furthermore, oomycete pathogen load varies between Z. marina root samples and the root samples of Z. japonica, another species of seagrass in the Puget Sound. Oomycete pathogen load was 94% lower in Z. japonica root tissue (n = 10) than Z. marina root tissue (n = 10; p = 0.008).


University of Puget Sound