Regulation of Cyanogenesis in Plants

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In black cherry (Prunus serotina) seeds, large-scale catabolism of the cyanogenic glycoside (R)-amygdalin to HCN occurs only upon tissue disruption. Antibodies will be raised against three glycoproteins (amygdalin hydrolase, prunasin hydrolase, and mandelonitrile lyase) catalyzing amygdalin degradation to determine their tissue and subcellular localizations by immunohistochemical techniques. Together with the localization of amygdalin by subcellular fractionation or immunochemical means, this will reveal the mode of compartmentation preventing cyanogenesis in intact seeds. Preliminary to future research on the genetic regulation of cyanogenesis, the phenomenon of cyanogensis will be followed during fruit development from flowering to maturity by measuring the levels of cyanogenic glycosides and of the above catabolic enzymes. The levels of mRNAs encoding these proteins will also be assessed by in vitro translation studies with methionine labeled with a radioisotope of sulfur. Many commercially important crops cause acute and chronic cyanide poisoning in humans and livestock due to the release of hydrogen cyanide (HCN) from cyanogenic glycosides by endogenous enzymes. This research will investigate the metabolism of cyanogenic glycosides in black cheryy. Detailed knowledge of the biosynthesis, sequestration, and degradation of these glycosides will greatly facilitate efforts to reduce the toxicity of such plants and clarify the role of cyanogenesis in plant-animal interactions.