ARS | Publication request: USING SINGLE STRAND CONFORMATIONAL POLYMOPHISMS (SSCP) TO IDENTIFY PHYTOPHTHORA SPECIES IN OREGON FORESTS AFFECTED BY SUDDEN OAKDEATH

Submitted to: International Union Of Forestry Research Organization
Publication Type: Proceedings
Publication Acceptance Date: July 19, 2004
Publication Date: September 11, 2004
Citation: 2004. Using single strand conformational polymophisms (sscp) to identify phytophthora species in oregon forests affected by sudden oakdeath. International Union Of Forestry Research Organization.

Technical Abstract: Phytophthora species are abundant in streams, widespread in soils and occasional indiseased plants in the tanoak forests of SW Oregon. It is time-consuming and expensive toidentify hundreds of isolates to species using morphology or ITS sequencing. We modifiedand calibrated a published Phytophthora SSCP protocol to allow quantitative matching ofunknown isolates. The method uses two color fluorescent markers and automatedmeasurement. Ninety six samples can be processed simultaneously. We drew a blindsample of eighty unknowns from a larger collection of isolates from streams, soil, and plants,and ran a preliminary test with sixteen reference Phytophthora species known from Oregon.SSCP distinguished 12 groups of unknowns; only three groups matched reference isolates.Several isolates matched P. ramorum and three matched P. ilicis. Several isolates fromstream samples were identified as P. nemorosa, previously known only from tanoak cankersin our area. Two isolates identified as P. ilicis came from tanoak bark or tanoak leaves, a newhost association for this species. The remaining nine unmatched groups suggest a largediversity of Phytophthora species in natural environments. Specimens from significantgroupings will be characterized by ITS sequence and morphology, with the expectation thatnew species will be discovered.