Comparison of Puccinia acroptili from Eurasia and the USA

Abstract

A rust disease caused by Puccinia acroptili P. Syd. & Syd. occurs throughout the range of Russian knapweed (Rhaponticum (syn. Acroptilon) repens), including North America. Differences in teliospore dimensions had been observed previously, but not quantified, between a specimen of P. acroptili from Turkey and one from the United States of America (USA). Similar differences were found during a recent evaluation of P. acroptili for biological control of R. repens in the USA; e.g., teliospores from eight USA isolates were 2.4 µm shorter (P = 0.05) than four isolates from Eurasia (two from Turkey, and one each from Russia and Kazakhstan). This inspired the generation of additional biological and DNA sequence data to clarify the significance of these differences between USA and Eurasian isolates. Although the USA isolates were found to have shorter teliospores, as noted in the description by Savile, teliospores of the USA isolates were also significantly wider in diameter than isolates from Eurasia; the latter in contrast to Savile's observation. Biologically, the isolates were the same; all were equally aggressive in causing disease under common greenhouse test conditions, and fertile crosses occurred between isolates regardless of source. DNA sequence analyses of the nuclear rDNA large subunit and internal transcribed spacer regions supported the notion that P. acroptili is a single species, but it also revealed that small levels of variation may exist within the species. For these reasons, it has been concluded that USA and Eurasian accessions can be considered a single species, i.e., P. acroptili. Also, Savile's observation about differences in spore dimensions is substantiated.Résumé : On retrouve une rouille pathogène causée par le Puccinia acroptili P. Syd. & Syd. sur l'ensemble de l'aire de la centaurée russe (Rhaponticum (syn. Acroptilon) repens), l'Amérique du Nord inclue. On a déjà observé des différences dans les dimensions des téliospores, mais sans les quantifier, entre des spécimens du P. acroptili de Turquie et un des États-Unis. On a également trouvé des différences similaires au cours d'une récente évaluation du P. acroptili, pour la lutte biologique du R. repens aux États-Unis; p. ex., les téliospores de 8 souches américains mesurent 2,4 µm de moins (P = 0,05) comparativement à 4 souches d'Eurasie (deux de Turquie, et une chacun pour la Russie et Kazakhstan). Ceci a motivé la recherche de nouvelles données biologiques et moléculaires pour clarifier la signification de ces différences entre les souches améri-cains et eurasiens. Bien qu'on retrouve des téliospores plus courtes chez les souches américains, tel que noté dans la description de Savile, les téliospores d'origine américaine sont également significativement plus larges en diamètre que les souches eurasiens -ces dernières étant différentes des observations de Savile. Biologiquement les souches sont semblables; toutes montrent la même agressivité à générer la maladie sous des conditions normales en serres, et on obtient des croisements fertiles...

Genera of phytopathogenic fungi: GOPHY 1

“…partheniicola BRIP 59295 – KX999864 Present study Pu. acroptili BPI 863523 JN204187 JN204187 Bruckart et al. (2012) Pu.…”

Identification of a rust disease of giant knapweed in the Czech Republic - short communication

“…& Syd. strains (all published by Bruckart et al 2012) (Bubák 1906) P. jaceae (Gäumann 1959) P. jaceae (Newcombe et al 2009) P. jaceae (Braun 1982) P. hieracii (Bubák 1906) P. hieracii (Gäumann 1959) P. hieracii (Hennen et al 2005) P. hieracii (Braun 1982 (Bubák 1906;Gäumann 1959;Braun 1982) compared to the specimen found on giant knapweed. From the remaining species, only P. hieracii and P. jaceae come into consideration, as they have two supra-equatorial pores (Braun 1982), just as our specimen.…”