Evidence of low levels of genetic diversity for the Phytophthora austrocedrae population in Patagonia, Argentina

VÉLEZ, M.L.; COETZEE P.A. ; WINGFIELD M.J. ; RAJCHENBERG M. ; GRESLEBIN A.G.

PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013

0032-0862

Phytophthora austrocedrae is a recently discovered pathogen that causes severe mortality of Austrocedrus chilensis inPatagonia. The high level of susceptibility of the host tree, together with the distribution pattern of the pathogen, haveled to the hypothesis that P. austrocedrae was introduced into Argentina. The aim of this study was to assess the populationstructure of P. austrocedrae isolates from Argentina in order to gain an understanding of the origin and spreadof the pathogen. Genetic diversity was determined based on amplified fragment length polymorphisms (AFLPs). Intotal, 48 isolates of P. austrocedrae were obtained from infected A. chilensis trees, representing the geographical rangeof the host. Four primer combinations were used for the AFLP analysis. Of the 332 scored bands, 12% were polymorphic.Gene diversity (h) ranged from 001 to 003; the Shannon index (I) ranged from 001 to 004. A high degree ofgenetic similarity was observed among the isolates (pairwise S values = 0958?1; 0993 0009, mean SD). A frequencyhistogram showed that most of the isolate pairs were identical. Principal coordinate analysis using three-dimensionalplots did not group any of the isolates based on their geographical origin. The low genetic diversity (within andbetween sites) and absence of population structure linked to geographic origin, together with the aggressiveness of thepathogen and the disease progression pattern, suggest that P. austrocedrae might have been introduced into Argentina.