Inheritance of antipathogenic factors and their occurrence in wheat seedlings

Research Project

Project/Area Number	03806021
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	製造化学・食品
Research Institution	KYOTO UNIVERSITY
Principal Investigator	IWAMURA Hajime Kyoto Univ., Agric. Chem., Professor, 農学部, 教授 (30026570)
Co-Investigator(Kenkyū-buntansha)	SHINOZAKI Masateru Kyoto Univ., Agric. Chem., Instructor, 農学部, 助手 (80115857) HIRAI Nobuhiro Kyoto Univ., Agric. Chem., Instructor, 農学部, 助手 (00165151)
Project Period (FY)	1991 – 1992
Project Status	Completed (Fiscal Year 1992)
Budget Amount *help	¥1,700,000 (Direct Cost: ¥1,700,000) Fiscal Year 1992: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1991: ¥1,300,000 (Direct Cost: ¥1,300,000)
Keywords	Triticum aestivum / Benzoxazinones / Phytoalexins / Plant immunity / Benzoxazinomes
Research Abstract	Wheat and corn plants produce phytoalexin substances, benzoxazinones, when infected by pathogenic microbes. It has been known that the precursors of the antipathogenic factors are benzoxazinone glucosides. We found that both glucosides and benzoxazinones appear when seeds germinate, and disappear when plants become self-supporting stage. In this study, we examined the time course and mechanism of their appearance. Authentic benzoxazinone glucosides were prepared by extraction of wheat seedlings and HPLC purification, and the aglycones were obtained by hydrolysis of the glucosides by glucosidases. The benzoxazinones in the extracts were indentified and quantified by HPLC. As the results, the glucosides appeared as seeds germinated, and the aglycones were observed to appear soon after in an amount sufficient for being active as antipathogens. The rate and quantity were little affected by terilization of seedlings, inoculation with patogenic fungi, and injury given by razor blade. These facts suggested that the benzoxazinones were not produced by induction of biosynthetic pathways, but as programmed action. The biosynthetic precursors of benzoxazinones were not found in the extracts of either sowed or dry seeds, suggesting that the de novo synthetic machinary is not at operate. Suggested were that benzoxazinones appeared are synthesized in parental generation and stored in seeds as insoluble form, plausibly as high molecular weight conjugates, and this gives support to the hypothesis that there exists kind of conferment of "immunity" by parents to the second generation.