Comparison of quantitative PCR and Lateral flow immunoassays for quantification of Botrytis cinerea in grape juice.

摘要

Two methods of quantifying Botrytis cinerea were compared against each other in wine grapes harvested from the Central Valley of California. Ninety-five samples harvested in 2006 were tested for rot using QuickStix, an immunological assay for Botrytis using lateral flow technology, and using a Q-PCR assay specific to B. cinerea. The standards used for QuickStix were extracts from suspensions of freeze dried mycelia in PBS. Standards for the Q-PCR assay were created by serially diluting pure DNA samples, and by extracting serially diluted B. cinerea spore suspensions.The standard curves for the spore suspensions and pure DNA serial dilutions showed R values of 0.99. Moreover, the two standard curves made using spores, one suspended in grape juice and the other in sterile water, showed no significant statistical differences. A statistical correlation was found between QuickStix and Q-PCR measurements of 95 unknown juice samples (R=.70). The range of results for DNA was 1.38 ng DNA/mL to 6300 ng DNA/mL and the range for QuickStix was 2.20 mug/mL to >100 mug/mL freeze dried mycelia extract.Some samples showed the presence of Botrytis cinerea DNA but did not show a positive result for Botrytis on the immunoassay lateral flow device. This may be due to the presence of spores, free DNA, or may be below the detection limit of the QuickStix assay. Three of the samples showed low amounts of DNA (1.38 ng/mL), but high levels of Botrytis antigens (>50 mug/mL) which may be due to damaged DNA due to freezing.