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Title: CHARACTERIZATION OF WILD OAT (AVENA FATUA) POLYPHENOL OXIDASE AND ITS POTENTIAL ROLE IN SEED LONGEVITY

Author
item Anderson, James
item Foley, Michael
item Kennedy, Ann
item FUERST, PATRICK - WASHINGTON ST UNIVERSITY

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2005
Publication Date: 2/13/2006
Citation: Anderson, J.V., Foley, M.E., Kennedy, A.C., Fuerst, P.E. 2006. Characterization of wild oat (Avena fatua) polyphenol oxidase and its potential role in seed longevity. [Abstract]. Weed Science Society of America Abstracts 46:31.

Interpretive Summary: Wild oat is an economically important weed of prairie environments and it can persist in the soil seed bank for multiple years prior to germination. Long-term survival in the soil seed bank requires not only dormancy, but also resistance to environmental stresses that could reduce seed viability. Since the enzyme polyphenol oxidase (PPO) is known to be induced by defense signals and by pathogen attack in plants, we are interested in determining its potential role in enhancing seed longevity of wild oat seeds. PPO activity was monitored in protein extracts obtained from seed tissue of wild oat at various stages of seed development. A wheat polyclonal PPO antibody was also used to monitor levels of wild oat PPO isoforms during seed development. Our data indicated the presence of multiple PPO isoforms in hulls but only one major PPO isoform in caryopses of developing wild oat seeds. After 4 days incubation at 25 C with the wild oat pathogen Fusarium avenaceum (isolate WF223A), PPO activity in dormant caryopses of wild oat doubled. These preliminary results implicate a potential role for PPO in the response of dormant wild oat seed to biotic stress and we are now examining PPO activity in hulls and caryopses of additional lines of wild oat.

Technical Abstract: Wild oat is an economically important weed of prairie environments and it can persist in the soil seed bank for multiple years prior to germination. Long-term survival in the soil seed bank requires not only dormancy, but also resistance to biotic and abiotic stresses that could reduce seed viability. Since polyphenol oxidase (PPO) is known to be induced by defense signals and by pathogen attack in plants, we are interested in determining its potential role in enhancing seed longevity of wild oat seeds. PPO activity was monitored in protein extracts obtained from hulls and caryopses of wild oat (M73) at various stages of seed development, using standard spectrophotometric assays. Fully developed [35 days post anthesis (DPA)] caryopses of wild oat have slightly less total PPO activity than hulls (257 vs. 306 U/gfwt, respectively). However, the specific activity of PPO in caryopses was ~5-fold less, which is likely associated with the ~4.5-fold reduction in the extractable protein content obtained from hulls at 35 DPA. A wheat polyclonal PPO antibody was also used to monitor levels of wild oat PPO isoforms during seed development, using standard Western blotting techniques. Polyclonal PPO antibody indicated the presence of multiple PPO isoforms in hulls but only one major PPO isoform in caryopses of developing wild oat. After 4 days incubation at 25 C with the wild oat pathogen Fusarium avenaceum (isolate WF223A), PPO activity in dormant caryopses of wild oat doubled. These preliminary results implicate a potential role for PPO in the response of dormant wild oat seed to biotic stress and we are now examining PPO activity in hulls and caryopses of additional lines of wild oat.