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United States Department of Agriculture

Agricultural Research Service

Research Project: CHEMICAL BIOLOGY OF INSECT AND PLANT SIGNALING SYSTEMS

Location: Chemistry Research Unit

Title: The novel maize 9-lipoxygenase, ZmLOX12, is required to mount an effective defense against Fusarium verticillioides

Authors
item Christensen, Shawn
item Nemchenko, Andriy -
item Park, Yong-Soon -
item Schmelz, Eric
item Kunze, Susan -
item Feussner, Ivo -
item Yalpani, Nasser -
item Meeley, Robert -
item Kolomiets, Michael -

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2013
Publication Date: N/A

Interpretive Summary: As an important agro-economical crop, maize has broad applications in the food, chemical, livestock, and biofuel industries. Fusarium verticillioides is a major limiting factor for maize production due to ear and stalk rot and the contamination of seed with the carcinogenic mycotoxin, fumonisin. Scientists from the USDA-ARS Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida in collaboration with Texas A&M University have identified a maize lipoxygenase, ZmLOX12, which provides resistance to the harmful pathogen F. verticillioides. Generation of a lox12 mutant resulted in increased susceptibility to F. verticillioides colonization of mesocotyls, stalks, and kernels and also supported higher levels of kernel fumonisin accumulation compared to wild-type plants. Diminished levels of the defense compound 12-oxo phytodienoic acid (OPDA) in lox12 mutants may explain the loss of resistance. This study demonstrates that the maize ZmLOX12 gene plays a key role in defense against F. verticillioides in diverse maize tissues.

Technical Abstract: Fusarium verticillioides is a major limiting factor for maize production due to ear and stalk rot and the contamination of seed with the carcinogenic mycotoxin, fumonisin. While lipoxygenase (LOX)-derived oxylipins have been implicated in defense against diverse pathogens, their function in maize resistance against F. verticillioides is poorly understood. Here, we cloned and functionally characterized a novel maize 9-LOX gene, ZmLOX12. Tissue expression analysis revealed that ZmLOX12 is predominantly expressed in maize mesocotyls, where it is strongly induced in response to F. verticillioides infection. Upregulation ofZmLOX12 can also occur in leaves following wounding or jasmonic acid application. Generation of a Mu-insertional lox12-1 mutant resulted in increased susceptibility to F. verticillioides colonization of mesocotyls, stalks, and kernels and also supported higher levels of kernel fumonisin accumulation compared to near-isogenic wild-type plants. Diminished levels of the jasmonic acid precursor 12-oxo phytodienoic acid (OPDA) in lox12 mutants may explain the loss of resistance. Interestingly, the more susceptible lox12 mutants accumulated higher levels of kauralexins, suggesting that F. verticillioides is tolerant to this group of antimicrobial phytoalexins. This study demonstrates that this unique monocot-specific 9-LOX plays a key role in defense against F. verticillioides in diverse maize tissues.

Last Modified: 4/23/2014
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