Characterization of aflatoxigenic and non-aflatoxigenic Aspergillus flavus isolates from pistachio

Hua, S.S.T. and McAlpin, C.E. and Chang, P-K. and Sarreal, S.B.L. (2012) Characterization of aflatoxigenic and non-aflatoxigenic Aspergillus flavus isolates from pistachio. Mycotoxin Research, 28 (1). pp. 67-75.

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Pistachio is a popular snack food. Aflatoxin contamination of pistachio nuts is a serious problem for many producing countries. The development of biological control methods based on ecological parameters is an environmentally friendly approach. Thirty-eight Aspergillus flavus isolates collected from a pistachio orchard in California (CA) were analyzed for production of aflatoxin (AF), cyclopiazonic acid (CPA), vegetative compatibility groups (VCGs), and mating types. All aflatoxigenic isolates produced both AFB1 and CPA. The most toxigenic one was CA28 which produced 164 μg AFB1 per 5 ml PDA fungal culture and small sclerotia (S strain, sclertoium size less than 400 μm). The other aflatoxigenic strains produce AFB1 ranging from 1.2 μg to 80 μg per 5 ml fungal culture. Twenty-one percent of the CA isolates produced AFB1, 84% produced CPA and half formed sclerotia on at least one of three tested media. The 38 CA isolates formed 26 VCGs, 6 of which had two or more isolates and 20 contained single isolates. The S strain isolates belong to 4 different VCGs. Genomic profiling by a retrotransposon DNA probe revealed fingerprint patterns that were highly polymorphic. The predicted VCGs (Pred-VCGs) based on a similarity coefficient >80% matched the VCGs of multiple isolates determined by complementation. All isolates within a VCG had the same mating-type gene of either MAT1-1 or MAT1-2. Uncorrected and VCG-corrected MAT1-1 and MAT1-2 among the isolates were equally distributed.

Item Type: Article
Additional Information: This work is supported by in-house research program funds from U.S. Department of Agriculture, Agricultural Research Services.
Uncontrolled Keywords: Aspergillus flavus, RFPL, Aflatoxin, Cyclopianzonic acid, VCG, Mating type, Pistachio
Author Affiliation: U. S. Department of Agriculture, Agricultural Research Service,Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710, USA email:
Subjects: Plant Protection > Pesticides
Divisions: General
Depositing User: Mr Siva Shankar
Date Deposited: 05 Oct 2012 06:06
Last Modified: 05 Oct 2012 06:06
Official URL:

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