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Abstract Detail


Plant-Pathogen Interactions

Snelling, Jacob [1], Davidson, Rebecca [2], Leach, Jan E. [2].

Hydrogen peroxide accumulation and oxalate oxidase activity correlate with quantitative disease resistance in rice.

Rice blast, caused by the fungal pathogen Magnaporthe grisea (Mg), contributes to heavy losses in rice (Oryza sativa) production each year. Understanding the molecular basis for quantitatively governed disease resistance is integral to successful management of the pathogen. Oxalate oxidase (OxOx) and germin-like protein (GLP) gene markers co-localize with rice blast quantitative trait loci (QTL) on chromosomes 3 and 8 in multiple rice mapping populations. Gene expression studies after Mg inoculation revealed that these genes may participate in early plant defense responses. H2O2 is a product of both OxOx and GLP activities. The purpose of this study was to use qualitative and quantitative indicators to determine if differential OxOx activity and H2O2 production correlate with quantitatively governed disease resistance. Two inoculation methods were optimized using rice lines SHZ-2, which exhibits quantitatively governed resistance to rice blast (QTL+), and LTH, which lacks the QTL, and is susceptible (QTL-). Leaf tissues were subjected to a series of biochemical assays including in situ staining for OxOx activity, enzyme-coupled quantitative measurement of OxOx activity, and in situ staining for H2O2 accumulation. Based on phenotypic and biochemical assays after inoculation with Mg, SHZ-2 accumulates higher levels of H2O2 earlier in the host-pathogen interaction than LTH. Substrate-specific activity assays showed that basal levels of OxOx activity are higher in SHZ-2 than LTH, and that the activity increased to higher levels in SHZ-2 after inoculation. These results are consistent with a role for H2O2 generating enzymes in QTL-governed blast disease resistance in rice.


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1 - Colorado State University, Bioagricultural Science and Pest Management, Campus Delivery 1177, Fort Collins, CO, 80523, United States
2 - Colorado State University, Bioagricultural Science and Pest Management

Keywords:
Oxalate Oxidase
Quantitative trait loci (QTL)
enzyme assays
Magnaporthe grisea.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P15060
Abstract ID:1436


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