Plant Physiology 91:415-420 (1989)
© 1989 American Society of Plant Biologists
Environmental and Stress Physiology
Induction of -Amylase Inhibitor Synthesis in Barley Embryos and Young Seedlings by Abscisic Acid and Dehydration Stress 1
Masumi Robertson,
M. Walker-Simmons,
Doug Munro and
Robert D. Hill
Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada,
U.S. Department of Agriculture, Agriculture Research Service, Wheat Genetics, Quality, Physiology and Disease Research, Washington State University, Pullman, Washington 99164-6420
An endogenous -amylase inhibitor was found to be synthesized in embryos of developing barley grain (Hordeum vulgare cv Bonanza). Accumulation of this protein occurred late in development (stage IV), at the same time that endogenous abscisic acid (ABA) showed a large increase. The inhibitor could be induced up to 23-fold in isolated immature embryos (stage III) by culture in ABA. Precocious germination was also blocked in stage III embryos by ABA. Dehydration stress on the isolated immature embryos also induced higher levels of the inhibitor and ABA. An even greater response to dehydration stress was observed in young seedlings, where inhibitor content increased 20-fold and ABA increased 80-fold during water stress. The high degree of correlation between ABA and inhibitor contents in in situ embryos, dehydrated embryos and young seedlings, as well as the increase in inhibitor caused by exogenously applied ABA to isolated embryos, suggests that increased -amylase inhibitor synthesis in response to dehydration stress is mediated by ABA.
1 Supported by a Natural Sciences and Engineering Research Council of Canada and a University of Manitoba Fellowship to M. R. and by NSERC Grants STR0032343 and OGP0004689. Paper No. 830 of the Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
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