Phytophthora nicotianae is a polyphagous pathogen with more than one thousand hosts. The genetic variability of a population of P. nicotianae isolates of both A1 and A2 mating types and from diverse host plants and geographic origins was determined by the analysis of two intergenic regions of the mitochondrial DNA. Two variable intergenic regions flanked by genes Trny and Rns (Trny/Rns) and by genes Trnw and Cox2 (Trnw/Cox2) were identified by comparing the whole mitochondrial genome of P. infestans, P. ramorum and P. sojae and were amplified and sequenced using primers designed on flanking conserved genes. Amplified regions showed a very variable length comprised between 429 and 927 bp (Trny/Rns) and between 323 and 600 bp (Trnw/Cox2). All sequences were aligned using Clustal X and the phylogenetic analysis was performed with the Neighbor-Joining method. The analyses of the Trny/Rns region enabled the identification of 16 clusters (threshold limit 0.001). No correlation was found between the grouping of isolates and their mating type, growth rate, colony morphology, place and host of origin, with the only exception of isolates from citrus. All isolates from citrus, in fact, were of A1 mating type and almost all were comprised in the same cluster, irrespective of their geographic origin. Similar results were also obtained with the Trnw/Cox2 region although this latter region enabled a less accurate separation of the isolates. Mitochondrial intergenic regions are suitable for studying intraspecific genetic variability in P. nicotianae.

Genetic variability of a population of Phytophthora nicotianae isolates from various hosts

PANE, Antonella;CACCIOLA, Santa Olga;
2009

Abstract

Phytophthora nicotianae is a polyphagous pathogen with more than one thousand hosts. The genetic variability of a population of P. nicotianae isolates of both A1 and A2 mating types and from diverse host plants and geographic origins was determined by the analysis of two intergenic regions of the mitochondrial DNA. Two variable intergenic regions flanked by genes Trny and Rns (Trny/Rns) and by genes Trnw and Cox2 (Trnw/Cox2) were identified by comparing the whole mitochondrial genome of P. infestans, P. ramorum and P. sojae and were amplified and sequenced using primers designed on flanking conserved genes. Amplified regions showed a very variable length comprised between 429 and 927 bp (Trny/Rns) and between 323 and 600 bp (Trnw/Cox2). All sequences were aligned using Clustal X and the phylogenetic analysis was performed with the Neighbor-Joining method. The analyses of the Trny/Rns region enabled the identification of 16 clusters (threshold limit 0.001). No correlation was found between the grouping of isolates and their mating type, growth rate, colony morphology, place and host of origin, with the only exception of isolates from citrus. All isolates from citrus, in fact, were of A1 mating type and almost all were comprised in the same cluster, irrespective of their geographic origin. Similar results were also obtained with the Trnw/Cox2 region although this latter region enabled a less accurate separation of the isolates. Mitochondrial intergenic regions are suitable for studying intraspecific genetic variability in P. nicotianae.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/57661
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