Isolation and identification of Phytophthora cinnamomi collected in avocado (Persea americana) from Northeast Colombia

Abstract

Phytophthora cinnamomi Rands is a root and collar root pathogen of a great number of wooden plants and crops around the world. The species is heterothallic requiring A1 and A2 mating types for sexual reproduction. In Colombia, P. cinnamomi represents one of the most limiting diseases in avocado (Persea americana Mill). In this work, a total of 207 P. cinnamomi isolates were analyzed from 664 symptomatic and asymptomatic avocado roots from Antioquia (Northeast Colombia) from 2014 to 2017 and morphological and molecular characterizations were conducted in 112 isolates. Rosaceous morphology was the most abundant. A haplotype network made with ITS sequences clustered haplotypes according to country of origin and host. H1 and H2 haplotypes represented P. cinnamomi var. cinnamomi and P. c. var. parvispora respectively and H12 haplotype represented P. c. var. robiniae. Non-Mendelian inheritance was found in the species according to microsatellite data corroborating previous reports made in Australia. P. cinnamomi from Antioquia was genetically structured (FST = 0.058, P = 0.001) suggesting reduced gene flow between sampling sites. Clonality estimations (obtained from a PCR-RFLP of the COI locus) in Antioquian P. cinnamomi were higher than in Australia and South Africa. Studies on next generation sequencing and reproductive isolation are required in this species in future investigations in Colombia.