Location: Grape Genetics Research Unit (GGRU)Title: The epiphytic microbiota of sour rot-affected grapes differs minimally from that of healthy grapes, indicating causal organisms are already present on healthy berries
|HALL, MEGAN - Cornell University - New York|
|O'BRYON, ISABELLE - Rochester Institute Of Technology|
|OSIER, MICHAEL - Rochester Institute Of Technology|
|WILCOX, WAYNE - Cornell University - New York|
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2019
Publication Date: 3/27/2019
Citation: Hall, M.E., O'Bryon, I., Osier, M.V., Wilcox, W.F., Cadle Davidson, L.E. 2019. The epiphytic microbiota of sour rot-affected grapes differs minimally from that of healthy grapes, indicating causal organisms are already present on healthy berries. PLoS One. https://doi.org/10.1371/journal.pone.0211378.
Interpretive Summary: Yeast and bacteria are consistently found on healthy grape berries worldwide. However, scientists have not fully characterized which microbes are present after disease. Sour rot is a disease involving the interaction between yeast, acetic acid bacteria and Drosophila fruit flies. To better understand whether sour rot microbes differ by region, we analyzed microbe DNA from sour rot-infected grapes in the U.S. and Australia across two years. Location was more important than presence of disease in determining which microbes were detected. The main difference between diseased and healthy samples was the increased presence of acetic acid bacteria in diseased samples. Yeasts were abundant in both healthy and diseased samples, but the specific yeast species detected varied by region. Because sour rot requires yeast, acetic acid bacteria and Drosophila fruit flies, our findings based on genetics are consistent with previous studies based on biology.
Technical Abstract: Yeast and bacteria are consistently found on healthy grape berries worldwide, in particular Pichia and Saccharomyces species, and many representatives of the Enterobacteraceae and Bacillaceae families. The ways in which these populations change when the berries are no longer healthy has not been explored on a large geographic or temporal scale. Sour rot is a disease complex involving the interaction between yeast, acetic acid bacteria and Drosophila fruit flies. To better understand whether sour rot microbial populations differ by region, we characterized the phytobiome of sour rot-infected grapes from four diverse geographical areas across two years. In 2015 and 2016, both healthy and sour-rot affected berries were collected from a research vineyard in Geneva, NY and commercial vineyards in Tasmania, AUS, and in 2016, sour-rot infected grapes were collected from vineyards in Fredonia, NY, and Modesto, CA. All associated organisms primarily grouped together by location, and not by presence/absence of symptoms. The predominant difference between asymptomatic and symptomatic samples that occurred regardless of location was in the presence of Acetobacter species, which were significantly more abundant in the symptomatic samples. Yeast genera such as Candida, Hanseniaspora, Pichia and Saccharomyces were abundant in both sets of samples, but varied by region. The consistent presence of yeast species and the increased abundance of acetic acid-generating bacteria is consistent with our understanding of sour rot etiology that requires these organisms, in addition to Drosophila, for symptom development.