Laboratory of Plant Science, Migal - Galilee Technology Center, Kiryat Shmona, Israel.
Tel-Hai College, Upper Galilee, Israel.
J Exp Bot. 2019 Aug 19;70(16):4105-4114. doi: 10.1093/jxb/erz134.
The sulfur-containing amino acid methionine belongs to the group of essential amino acids, meaning that humans and animals must consume it in their diets. However, plant seeds have low levels of methionine, limiting their nutritional potential. For this reason, efforts have been made over the years to increase methionine levels in seeds. Here, we summarize these efforts and focus particularly on those utilizing diverse genetic and molecular tools. Four main approaches are described: (i) expression of methionine-rich storage proteins in a seed-specific manner to incorporate more soluble methionine into the protein fraction; (ii) reduction of methionine-poor storage proteins inside the seeds to reinforce the accumulation of methionine-rich proteins; (iii) silencing methionine catabolic enzymes; and (iv) up-regulation of key biosynthetic enzymes participating in methionine synthesis. We focus on the biosynthetic genes that operate de novo in seeds and that belong to the sulfur assimilation and aspartate family pathways, as well as genes from the methionine-specific pathway. We also include those enzymes that operate in non-seed tissues that contribute to the accumulation of methionine in seeds, such as S-methylmethionine enzymes. Finally, we discuss the biotechnological potential of these manipulations to increase methionine content in plant seeds and their effect on seed germination.
含硫氨基酸蛋氨酸属于必需氨基酸组，这意味着人类和动物必须在饮食中摄入它。然而，植物种子中的蛋氨酸含量很低，限制了它们的营养潜力。出于这个原因，多年来人们一直致力于提高种子中的蛋氨酸水平。在这里，我们总结了这些努力，并特别关注那些利用多种遗传和分子工具的努力。描述了四种主要方法：（i）以种子特异性的方式表达富含蛋氨酸的储存蛋白，将更多可溶的蛋氨酸掺入蛋白质部分；（ii）减少种子内的蛋氨酸贫乏储存蛋白，以加强富含蛋氨酸的蛋白积累；（iii）沉默蛋氨酸分解代谢酶；和（iv）上调参与蛋氨酸合成的关键生物合成酶。我们专注于在种子中从头开始运作且属于硫同化和天冬氨酸家族途径的生物合成基因，以及来自蛋氨酸特异性途径的基因。我们还包括那些在非种子组织中运作的酶，这些酶有助于蛋氨酸在种子中的积累，例如 S-甲基蛋氨酸酶。最后，我们讨论了这些操纵增加植物种子中蛋氨酸含量的生物技术潜力及其对种子发芽的影响。
