Regulation of Cyanogenesis in Plants

在黑樱桃(Prunus Serotina)种子中，生氰苷(R)-苦杏仁苷仅在组织破裂时才发生大规模分解代谢为HCN。我们将针对催化杏仁苷降解的三种糖蛋白(杏仁苷水解酶、扁桃体蛋白水解酶和扁桃腈裂解酶)产生抗体，通过免疫组织化学技术来确定它们的组织和亚细胞定位。结合通过亚细胞分离或免疫化学方法定位苦杏仁苷，这将揭示阻止完整种子氰化物发生的区隔模式。在进一步研究氰化物发生的遗传调控之前，将通过测定生氰糖苷和上述分解代谢酶的水平来跟踪果实从开花到成熟的发育过程中的氰化现象。编码这些蛋白质的mRNAs的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会引起人和牲畜的急性和慢性氰化物中毒，原因是内源性酶从生氰苷中释放出氰化氢(HCN)。本研究将对黑菊花中生氰糖苷的代谢进行研究。对这些糖苷的生物合成、封存和降解的详细了解将极大地促进降低此类植物毒性的努力，并阐明氰化在动植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.