Journal article
Induction of Polyphenol Oxidase Activity in Dormant Wild Oat (Avena fatua) Seeds and Caryopses: A Defense Response to Seed Decay Fungi
Weed science, Vol.59(2), pp.137-144
06/2011
Handle:
https://hdl.handle.net/2376/109168
Abstract
Persistence of the soil seed bank requires both dormancy and resistance to seed decay organisms. However, there is little or no information evaluating biochemical responses of dormant weed seeds to pathogens. Wild oat caryopses were incubated with four pathogenic fungal isolates to evaluate the response of the pathogen defense enzyme, polyphenol oxidase (PPO). Caryopsis PPO activity was induced by three Fusarium spp. isolates previously obtained from whole seeds incubated in the field whereas caryopsis PPO activity was decreased by a Pythium isolate. Fusarium avenaceum isolate F.a.1 caused the greatest PPO induction and was studied in more detail. When whole wild oat seeds were incubated on F.a.1, PPO activity was induced in seeds, hulls (lemma and palea), and caryopses. Incubation of whole seeds on F.a.1 gradually induced caryopsis PPO activity over an 8-d period, whereas incubation of caryopses on F.a.1 over a 4-d period caused a greater and more rapid induction of PPO activity. Very little PPO activity could be leached from untreated caryopses, but nearly all of the induced PPO activity in F.a.1-treated caryopses was readily leached when incubated in buffer. In Western blots, both untreated and F.a.1-treated leachates contained a ∼57-kilodalton (kD) protein, putatively the mature and relatively inactive form of PPO. However, lower molecular weight antigenic proteins between ∼52 and ∼25 kD were strongly induced in F.a.1-treated caryopses, with this induction being correlated with the increase in PPO activity. We hypothesize that dormant weed seeds possess biochemical defenses against pathogens and, more specifically, that proteolysis in the presence of fungal pathogens may release an activated form of PPO from the surface of wild oat caryopses and hulls.
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Details
- Title
- Induction of Polyphenol Oxidase Activity in Dormant Wild Oat (Avena fatua) Seeds and Caryopses: A Defense Response to Seed Decay Fungi
- Creators
- E. Patrick Fuerst - Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164James V Anderson - USDA-ARS, Biosciences Research Laboratory, 1605 Albrecht Blvd, Fargo, ND 58102Ann C Kennedy - USDA-ARS, Land Management and Water Conservation, 215 Johnson Hall, Washington State University, Pullman WA 99164Robert S Gallagher - Department of Crop and Soil Sciences, The Pennsylvania State University, University Park, PA 16801
- Publication Details
- Weed science, Vol.59(2), pp.137-144
- Academic Unit
- Crop and Soil Sciences, Department of
- Publisher
- Cambridge University Press; Cambridge, UK
- Number of pages
- 8
- Identifiers
- 99900547747501842
- Language
- English
- Resource Type
- Journal article