Regulation of Cyanogenesis in Plants

在黑樱桃（Prunus sertina）种子中，氰基苷(R)-苦杏仁苷的大规模分解代谢仅发生在组织破坏时。针对三种催化苦杏仁苷降解的糖蛋白（苦杏仁苷水解酶、prunasin水解酶和扁桃腈裂解酶）产生抗体，通过免疫组织化学技术确定其组织和亚细胞定位。结合亚细胞分离或免疫化学方法对苦杏仁苷的定位，这将揭示在完整的种子中防止氰化的区隔模式。为进一步研究青化的遗传调控，我们将通过测定青化苷和上述分解代谢酶的水平来跟踪果实从开花到成熟的整个发育过程中的青化现象。编码这些蛋白质的mrna水平也将通过用硫的放射性同位素标记的蛋氨酸进行体外翻译研究来评估。许多重要的商业作物由于内源性酶从氰苷中释放氰化氢（HCN）而导致人类和牲畜急性和慢性氰化物中毒。本研究旨在探讨黑樱桃中氰苷的代谢。对这些苷的生物合成、隔离和降解的详细了解将极大地促进减少这些植物毒性的努力，并阐明氰生成在植物-动物相互作用中的作用。

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.