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ARS Home » Southeast Area » Poplarville, Mississippi » Southern Horticultural Research Unit » Research » Publications at this Location » Publication #292248
Title: Three novel phytophthora species from irrigation water in Mississippi

Author
item YANG, XIAO - Virginia State University
item Copes, Warren
item HONG, CHUANXUE - Virginia State University

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2013
Publication Date: 6/1/2013
Citation: Yang, X., Copes, W.E., Hong, C. 2013. Three novel phytophthora species from irrigation water in Mississippi. Phytopathology. 103:S2.164.

Interpretive Summary:

Technical Abstract: The genus Phytophthora includes a number of destructive plant pathogens. Here we report three new taxa recovered from irrigation systems at an ornamental crop nursery in Mississippi. Isolates of these new taxa were recovered from rhododendron leaves submerged in ponds for 7 days in 2012. Isolates from the three taxa produce a single-strand conformation polymorphism (SSCP) fingerprint that is distinct from all known species of Phytophthora. . These three new taxa belong to the ITS clades 2, 6 and 8, respectively, and provisionally are named as Phytophthora stricta, P. mississippiae, and P. macilentosa by morphology and sequence analysis. All isolates of these species are A1 mating types and produce golden-walled oogonia when paired with an A2 tester of P. cinnamomi. Morphologically, P. stricta is featured by semi-papillate sporangia and constriction in the sporangiophore. P. mississippiae produces semi-papillate and non-caducous sporangia as well as catenulate intercalary hyphal swellings. P. macilentosa is named after its characteristic skinny sporangia, which account for half of the sporangia observed. P. macilentosa is also characterized by massive growth at 35'. The pathogenicity of these three species is being tested on rhododendron, pieris, hydrangea, daphne plants. Recovery and description of these novel species will help assess Phytophthora disease risk locally and protect the plant biosecurity globally.