据介绍，防御性生物碱芦竹碱（gramine）不仅保护大麦和其他禾草免受昆虫侵害，还会降低它们对反刍动物的适口性。芦竹碱形成的关键基因一直未知，这阻碍了育种工作的开展。
研究人员报告了一个编码细胞色素P450单加氧酶CYP76M57的基因，并将其命名为AMI合酶（AMIS），它使烟草（Nicotiana benthamiana）、拟南芥（Arabidopsis thaliana）和酿酒酵母（Saccharomyces cerevisiae）能够产生芦竹碱。研究人员在不含芦竹碱的大麦（Hordeum vulgare）品种Golden Promise中重建了芦竹碱的产生，并通过Cas介导的基因编辑从品种Tafeno中消除了它。体外实验揭示了一个意外的隐秘氧化重排过程，这一非典型转化涉及氨基酸到缩短链生物胺的转换。
总之，芦竹碱形成相关遗传基础的发现，将允许通过植物育种对大麦中与芦竹碱相关的性状进行量身定制的优化。
附：英文原文
Title: Biosynthesis of the allelopathic alkaloid gramine in barley by a cryptic oxidative rearrangement
Author: Sara Leite Dias, Ling Chuang, Shenyu Liu, Benedikt Seligmann, Fabian L. Brendel, Benjamin G. Chavez, Robert E. Hoffie, Iris Hoffie, Jochen Kumlehn, Arne Bültemeier, Johanna Wolf, Marco Herde, Claus-Peter Witte, John C. D’Auria, Jakob Franke
Issue&Volume: 2024-03-29
Abstract: The defensive alkaloid gramine not only protects barley and other grasses from insects but also negatively affects their palatability to ruminants. The key gene for gramine formation has remained elusive, hampering breeding initiatives. In this work, we report that a gene encoding cytochrome P450 monooxygenase CYP76M57, which we name AMI synthase (AMIS), enables the production of gramine in Nicotiana benthamiana, Arabidopsis thaliana, and Saccharomyces cerevisiae. We reconstituted gramine production in the gramine-free barley (Hordeum vulgare) variety Golden Promise and eliminated it from cultivar Tafeno by Cas-mediated gene editing. In vitro experiments unraveled that an unexpected cryptic oxidative rearrangement underlies this noncanonical conversion of an amino acid to a chain-shortened biogenic amine. The discovery of the genetic basis of gramine formation now permits tailor-made optimization of gramine-linked traits in barley by plant breeding.
DOI: adk6112
Source: https://www.science.org/doi/10.1126/science.adk6112