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- Title
Polyphenol oxidase as a biochemical seed defense mechanism.
- Authors
Fuerst, E. Patrick; Okubara, Patricia A.; Anderson, James V.; Morris, Craig F.
- Abstract
Seed dormancy and resistance to decay are fundamental survival strategies, which allow a population of seeds to germinate over long periods of time. Seeds have physical, chemical, and biological defense mechanisms that protect their food reserves from decay-inducing organisms and herbivores. Here, we hypothesize that seeds also possess enzyme-based biochemical defenses, based on induction of the plant defense enzyme, polyphenol oxidase (PPO), when wild oat (Avena fatua L.) caryopses and seeds were challenged with seed-decaying Fusarium fungi. These studies suggest that dormant seeds are capable of mounting a defense response to pathogens. The pathogen-induced PPO activity from wild oat was attributed to a soluble isoform of the enzyme that appeared to result, at least in part, from proteolytic activation of a latent PPO isoform. PPO activity was also induced in wild oat hulls (lemma and palea), non-living tissues that cover and protect the caryopsis. These results are consistent with the hypothesis that seeds possess inducible enzyme-based biochemical defenses arrayed on the exterior of seeds and these defenses represent a fundamental mechanism of seed survival and longevity in the soil. Enzyme-based biochemical defenses may have broader implications since they may apply to other defense enzymes as well as to a diversity of plant species and ecosystems.
- Subjects
POLYPHENOL oxidase; SEED dormancy; FUSARIUM; SEED enzymes; PLANT defenses
- Publication
Frontiers in Plant Science, 2014, Vol 5, p1
- ISSN
1664-462X
- Publication type
Article
- DOI
10.3389/fpls.2014.00689