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United States Department of Agriculture

Agricultural Research Service

Research Project: Exotic and Emerging Plant Diseases of Horticultural Crops

Location: Horticultural Crops Research

Title: Identification of Phytophthora species baited and isolated from forest soil and streams in northwestern Yunnan province, China

Authors
item Huai, Wx -
item Tian, G -
item Hansen, Everett -
item Zhao, Wx -
item Goheen, Ellen -
item Grunwald, Niklaus
item Cheng, C -

Submitted to: Forest Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 11, 2012
Publication Date: January 21, 2013
Citation: Huai, W., Tian, G., Hansen, E.M., Zhao, W., Goheen, E.M., Grunwald, N.J., Cheng, C. 2013. Identification of Phytophthora species baited and isolated from forest soil and streams in northwestern Yunnan province, China. Forest Pathology. 43 (2013) 87–103.

Interpretive Summary: Plant pathogens in the water mold genus Phytophthora are important pathogens in forest ecosystems. Not much is known about Phytophthora species diversity in forests in NW Yunnan Province, China. Phytophthora species were surveyed in the years 2005, 2006 and 2010 at three sites in oak forests in Diqing Tibetan Autonomous Prefecture of NW Yunnan province, China. A total of seventy-three isolates of Phytophthora were recovered. Eight species were identified included two well-known species P. gonapodyides and P. cryptogea, two recently described species P. gregata and P. plurivora, two named temporarily but as yet not formally described taxa, and two potentially new species not yet described. There was a relatively rich species and genetic diversity of Phytophthora detected in the investigated regions where the forest biotic and abiotic factors affecting the growth and evolution of Phytophthora populations were diverse. This work had implications for understanding the global biodiversity of Phytophthora species in forest environments.

Technical Abstract: Phytophthora species were surveyed by collecting soil samples and placing bait leaves in selected streams during June - October in the years 2005, 2006 and 2010 at three sites in oak forests in Diqing Tibetan Autonomous Prefecture of NW Yunnan province, China. Seventy-three isolates of Phytophthora spp. were recovered from 135 baited leaf samples and 81 soil samples. Eight Phytophthora species were identified by observation of morphological features and ITS1-5.8S-ITS2 rDNA sequence analysis. The eight taxa included two well-known species P. gonapodyides and P. cryptogea, two recently described species P. gregata and P. plurivora, two named but as yet undescribed taxa, P. taxon PgChlamydo and P. taxon Salixsoil, and two previously unrecognized species, Phytophthora sp.1 and P. sp.2. The most numerous species, P. taxon PgChlamydo, and the second most abundant species, P. taxon Salixsoil, were recovered at all three sites. Phytophthora cryptogea was detected only once at site Nixi. Phytophthora gregata and P. sp.2 were isolated from a stream only at site Bitahai, while the other three species were each found at two sites. Phylogenetic analysis revealed that the isolates belonged to three ITS clades, one species including six isolates in clade 2, six species including 66 isolates in clade 6 and one species in clade 8. There was a relatively rich species and genetic diversity of Phytophthora detected in the investigated regions where the forest biotic and abiotic factors affecting the growth and evolution of Phytophthora populations were diverse.

Last Modified: 11/26/2014
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