|WANG, XUEFEI - Washington State University|
|KRAMER, ELIZABETH - Washington State University|
|GLAWE, DEAN - Washington State University|
Submitted to: Washington Association of Wine Grape Growers Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/20/2016
Publication Date: 2/20/2016
Citation: Wang, X., Kramer, E., Glawe, D., Okubara, P.A. 2016. Grape Berry Colonization and Biological Control of Botrytis cinerea by Indigenous Vineyard Yeasts. Washington Association of Wine Grape Growers Annual Meeting. http://wawgg.org/wawgg-annual-meeting-convention-and-tradeshow_38.html.
Technical Abstract: Botrytis bunch rot, caused by Botrytis cinerea, is the most important disease of grape berries, especially during transportation and storage. Biological control is a potential means of postharvest management of Botrytis bunch rot. The study was aimed at testing the hypothesis that antagonistic yeasts are indigenous in vineyards and would effectively control disease development of Botrytis bunch rot on table grapes. Our objectives were to evaluate indigenous yeast strains for colonization capability and antagonistic activity against B. cinerea on wounded Thompson Seedless berries. In a previous study, fifty indigenous yeasts strains of 16 different genera, isolated from Washington vineyards, were tested for suppressive activity. In this study, eleven of these strains were re-tested using new in vitro and in vivo inhibition assays. Aureobasidium pullulans var. pullulans P01A006 showed inhibitory effects against nine pathogenic B. cinerea isolates. The other yeast species, including Candida saitoana, Curvibasidium pallidicorallinum, Metschnikowia chrysoperlae, Metschnikowia aff. pulcherrima, Meyerozyma guilliermondii, Saccharomyces cerevisiae and Wickerhamomyces anomalus, inhibited one to three pathogen isolates. Yeast cell suspensions (20-2000 cells/wound) applied to artificial wounds consistently reached populations of log 5.91 - 6.78 cells after 10 days in berry tissue. Saccharomyces cerevisiae HNN11516 was an exception, barely maintaining log 5. Ten yeast strains caused mild to moderate discoloration of the berry skin and internal tissues around the wound, but none caused the necrosis characteristic of pathogens. The most comprehensive antagonistic activity was shown by A. pullulans P01A006, which reduced symptom development and sporulation of B. cinerea on berries. Our findings indicate that antagonistic yeasts with promising biocontrol activity against B. cinerea can be found among the indigenous microflora, and certain yeasts could provide antagonistic activity in planta. However, extensive formulation and storage trials will be needed to assess the efficacy of the indigenous yeasts in the commercial setting.