February
2009
, Volume
22
, Number
2
Pages
222
-
231
Authors
Xiquan Gao,1
Marion Brodhagen,2
Tom Isakeit,1
Sigal Horowitz Brown,2
Cornelia Göbel,3
Javier Betran,4
Ivo Feussner,3
Nancy P. Keller,2 and
Michael V. Kolomiets1
Affiliations
1Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX, 77843-2132, U.S.A.; 2Departments of Plant Pathology and Medical Microbiology and Immunology, University of Wisconsin-Madison, 1550 Linden Dr., Madison, WI 53706-1598, U.S.A.; 3Department of Plant Biochemistry, Georg-August-University, Göttingen, Justus-von-Liebig-Weg 11, D-37077 Göttingen, Germany; 4Department of Soil and Crop Sciences, Corn Breeding and Genetics, Texas A&M University
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RelatedArticle
Accepted 17 October 2008.
Abstract
Plant and fungal lipoxygenases (LOX) catalyze the oxidation of polyunsaturated fatty acids, creating fatty-acid hydroperoxides (oxylipins). Fungal oxylipins are required for normal fungal development and secondary metabolism, and plant host--derived oxylipins interfere with these processes in fungi, presumably by signal mimicry. The maize LOX gene ZmLOX3 has been implicated previously in seed-Aspergillus interactions, so we tested the interactions of a mutant maize line (lox3-4, in which ZmLOX3 is disrupted) with the mycotoxigenic seed-infecting fungi Aspergillus flavus and Aspergillus nidulans. The lox3-4 mutant was more susceptible than wild-type maize to both Aspergillus species. All strains of A. flavus and A. nidulans produced more conidia and aflatoxin (or the precursor sterigmatocystin) on lox3-4 kernels than on wild-type kernels, in vitro and under field conditions. Although oxylipins did not differ detectably between A. flavus--infected kernels of the lox3-4 and wild-type (WT) maize, oxylipin precursors (free fatty acids) and a downstream metabolite (jasmonic acid) accumulated to greater levels in lox3-4 than in WT kernels. The increased resistance of the lox3-4 mutant to other fungal pathogens (Fusarium, Colletotrichum, Cochliobolus, and Exserohilum spp.) is in sharp contrast to results described herein for Aspergillus spp., suggesting that outcomes of LOX-governed host-pathogen interactions are pathogen-specific.
JnArticleKeywords
Additional keywords:9S-HPODE, Fusarium verticillioides.
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© 2009 The American Phytopathological Society