Posted by: HortAlaska | May 9, 2019

Genetic Analysis Reveals Unprecedented Diversity of a Globally-important Plant Pathogenic Genus

Andrea R. Garfinkel , Katie p. Coats, Don L. sherry & Gary A. Chastagner

Science Reports

Genus Botrytis contains approximately 35 species, many of which are economically-important and globally-distributed plant pathogens which collectively infect over 1,400 plant species. Recent effortsto genetically characterize genus Botrytis have revealed new species on diverse host crops around the world. In this study, surveys and subsequent genetic analysis of the glyceraldehyde-3-phosatedehydrogenase (G3PDH), heat-shock protein 60 (HSP60), DNA-dependent RNA polymerase subunit II (RPB2), and necrosis and ethylene-inducing proteins 1 and 2 (NEP1 and NEP2) genes indicated thatBotrytis isolates collected from peony fields in the United States contained more species diversity
than ever before reported on a single host, including up to 10 potentially novel species. Together, up to 16 different phylogenetic species were found in association with peonies in the Pacific Northwest, which is over a third of the total number of species that are currently named. Furthermore, species were found on peonies in Alaska that have been described on other host plants in different parts of the world, indicating a wider geographic and host distribution than previously thought. Lastly, some isolates found on peony share sequence similarity with unnamed species found living as endophytes in weedy hosts, suggesting that the isolates found on peony have flexible lifestyles as recently discovered in the genus. Selected pathogenicity, growth, and morphological characteristics of the putatively newBotrytis species were also assessed to provide a basis for future formal description of the isolates as newspecies.

Andrea Garfinkel completed a genetic analysis of Botrytis species that she found in Alaska Peony fields as well as several other locations. The article describes her analysis of gray mold she found on peonies. The taxonomy is quite complex but the bottom line is, there is significantly greater biodiversity of Botrytis species in the US than has ever been reported, especially for a single host species, the peony.

The relative frequency of Botrytis species collected from peony differed by survey region. In Washington and Oregon (combined), the majority of samples were identified as B. paeoniae (51%), followed by B. cinerea (29%). Only 8% of the samples (n = 6) collected in Washington and Oregon (all of which were collected in Washington) did not belong to either B. cinerea, B. paeoniae, or B. pseudocinerea. On the contrary, 37% of the samples found in Alaska were species other than B. cinerea, B. paeoniae, or B. pseudocinerea, closely followed by isolates that were identified as B. cinerea (40%).

Basically, Alaska has the greatest diversity of Botrytis species of all regions tested, and a great majority of the samples could not be identified to known species. The authors speculated that maybe because Alaska is quite young in agriculture and still has a lot of wilderness, the diversity could originate from surrounding areas. It is not known how many of these new types are actually pathogenic on peonies. Yet another study, I’m sure!


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