Lima bean, Phaseolus lunatus, is a crop legume that produces the cyanogenic glucosides linamarin and lotaustralin. In the legumes Lotus japonicus and Trifolium repens, the biosynthesis of these two α‐hydroxynitrile glucosides involves cytochrome P450 enzymes of the CYP79 and CYP736 families and a UDP‐glucosyltransferase. Here, we identify CYP79D71 as the first enzyme of the pathway in P. lunatus, producing oximes from valine and isoleucine. A second CYP79 family member, CYP79D72, was shown to catalyze the formation of leucine‐derived oximes, which act as volatile defense compounds in Phaseolus spp. The organization of the biosynthetic genes for cyanogenic glucosides in a gene cluster aided their identification in L. japonicus. In the available genome sequence of P. vulgaris, the gene orthologous to CYP79D71 is adjacent to a member of the CYP83 family. Although P. vulgaris is not cyanogenic, it does produce oximes as volatile defense compounds. We cloned the genes encoding two CYP83s (CYP83E46 and CYP83E47) and a UDP‐glucosyltransferase (UGT85K31) from P. lunatus, and these genes combined form a complete biosynthetic pathway for linamarin and lotaustralin in Lima bean. Within the genus Phaseolus, the occurrence of linamarin and lotaustralin as functional chemical defense compounds appears restricted to species belonging to the closely related Polystachios and Lunatus groups. A preexisting ability to produce volatile oximes and nitriles likely facilitated evolution of cyanogenesis within the Phaseolus genus.

中文翻译：

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菜豆中氰苷的生物合成和基于肟的防御的进化。


利马豆（ Phaseolus lunatus ）是一种豆类作物，可产生氰苷亚麻苦甙和莲藕甙。在豆科植物百脉根和白三叶草中，这两种 α-羟基腈葡萄糖苷的生物合成涉及 CYP79 和 CYP736 家族的细胞色素 P450 酶和 UDP-葡萄糖基转移酶。在这里，我们将 CYP79D71 确定为P. lunatus中该途径的第一个酶，从缬氨酸和异亮氨酸产生肟。 CYP79 家族的第二个成员 CYP79D72 被证明可以催化亮氨酸衍生肟的形成，这些肟在菜豆属中充当挥发性防御化合物。氰苷生物合成基因在基因簇中的组织有助于在日本乳杆菌中对其进行鉴定。在普通假单胞菌的可用基因组序列中，与CYP79D71同源的基因与CYP83家族的成员相邻。尽管普通假单胞菌不产生氰，但它确实产生肟作为挥发性防御化合物。我们从月圆藻中克隆了编码两个CYP83（CYP83E46和CYP83E47）和一个UDP-葡萄糖基转移酶（UGT85K31）的基因，这些基因组合形成了利马豆中亚麻苦苷和莲花素的完整生物合成途径。在菜豆属中，亚麻苦苷和莲花素作为功能性化学防御化合物的出现似乎仅限于属于密切相关的多穗属和新月属的物种。预先存在的产生挥发性肟和腈的能力可能促进了菜豆属内氰化的进化。