Quiescent infections play key roles in Botrytis cinerea pathogenesis and in the management of Botrytis bunch rot on Vitis spp. An improved understanding of the biology of quiescence and identification of resistant germplasm could result in improved disease management. In 2004 and 2005, two methods were applied to monitor quiescence and activation of natural B. cinerea infections on 32 genotypes of Vitis spp. and interspecific hybrids. In addition to the standard assay for early detection of B. cinerea, based on tissue freezing and incubation, a real-time quantitative PCR (qPCR) assay was developed and tested. Based on Taqman chemistry, this qPCR assay quantified as little as 3.2 pg of B. cinerea DNA accurately, with a detection limit of 100 fg, and did not amplify grape DNA. The qPCR and freezing assays detected infection levels of B. cinerea in both 2004 and 2005 appropriate to the actual disease severity (22.5% and 1.0% bunch rot, respectively). Grape genotypes varied in their resistance to infection, degree of colonization, and severity of disease. qPCR was not as effective as the freezing assay for detecting infection at early stages of development but was able to quantify fungal colonization, resulting in a new capability for monitoring B. cinerea pathogenesis over time. The combined ability of the two assays to detect B. cinerea early in berry development and monitor colonization provides a resource for informing disease management decisions and for identifying mechanisms of disease resistance.
- Copyright © 2008 by the American Society for Enology and Viticulture