Poster Session: Biology and Disease Management - Biological Control
209-P
Use of propidium monoazide and qPCR to quantify viable and nonviable conidia of Aspergillus flavus in almond soils .
A. ORTEGA-BELTRAN (1), Y. Luo (1), T. J. Michailides (1)
(1) University of California, Davis, Kearney Agricultural Research and Extension Center, Parlier, CA, U.S.A.
Aflatoxins, produced mainly by Aspergillus flavus and A. parasiticus, are carcinogenic compounds that pose serious health threats. In California, almonds are occasionally contaminated with aflatoxins. However, climate change is increasing the frequencies of aflatoxin contamination events. The atoxigenic isolate Aspergillus flavus AF36 is a biocontrol agent registered with the EPA for use in California, Arizona, and Texas to limit aflatoxin accumulation of cottonseed, maize, and pistachio. Registration of AF36 for use in almond is being sought. However, use of multiple atoxigenics may allow for additive and long-term reduction in aflatoxin-producing potential of fungal communities associated with cultivated and non-cultivated areas. Use of atoxigenics (i) adapted to target crops, (ii) highly competitive, and (iii) able to thrive in distinct soil types would enhance long-term residence of the applied atoxigenics throughout a target area. Using propidium monoazide (PMA), a DNA-binding dye, along with real-time polymerase chain reaction (qPCR) allows for quantification of viable and nonviable conidia. Survival of atoxigenics in distinct almond soil types was monitored with a PMA-qPCR protocol. Results revealed differential soil adaptation among the examined atoxigenics. These results will aid in the selection of atoxigenics to integrate a biocontrol mixture for future registration with the EPA to limit aflatoxin accumulation of almond and other susceptible crops.