Natural variation in theOsbZIP18promoter contributes to branched-chain amino acid levels in rice
Natural variation in theOsbZIP18promoter contributes to branched-chain amino acid levels in rice
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OsbZIP18 启动子的自然变异有助于水稻支链氨基酸水平
DOI：
10.1111/nph.16800
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发表时间：
2020-08-06
期刊：
影响因子：
9.4
通讯作者：
Luo, Jie
中科院分区：
文献类型：
--
作者：
Sun, Yangyang;Shi, Yuheng;Luo, Jie
支链氨基酸（BCAA）是人类和动物必须从饮食中获得的必需氨基酸，它们在植物生长和发育的各个方面起着重要作用。虽然BCAA在高等植物中的生物合成途径已经被发现，但其遗传控制的知识仍然有限，迄今为止还没有发现积极的调节剂。在这里，我们表明，在水稻中的支链氨基酸水平的变化是由于差异转录OsbZIP18，碱性亮氨酸拉链（bZIP）转录因子，由于其启动子的多态性。功能分析表明，OsbZIP 18通过直接与生物合成基因支链氨基转移酶1（branchedchainaminotransferase1，OsBCAT 1）和OsBCAT 2启动子中的ACE和C-box顺式元件结合，正调控支链氨基酸的合成。我们进一步证明OsbZIP18是由氮（N）缺乏强烈诱导的，并且N饥饿以OsbZIP18依赖的方式导致BCAA水平的增强。总之，我们鉴定了OsbZIP 18，一种BCAA生物合成的正调节因子，其通过直接调节关键生物合成基因OsBCAT 1和OsBCAT 2，促进BCAA水平的自然变化并介导BCAA通过新合成的积累。
Branched-chain amino acids (BCAAs) are essential amino acids that must be obtained from the diet for humans and animals, and they play important roles in various aspects of plant growth and development. Although BCAA biosynthetic pathways in higher plants have been uncovered, knowledge of their genetic control is still limited, and no positive regulators have been identified to date. Here, we showed that variation in BCAA levels in rice is attributable to differential transcription ofOsbZIP18, a basic leucine zipper (bZIP) transcription factor, due to polymorphisms in its promoter. Functional analysis revealed thatOsbZIP18positively regulates BCAA synthesis by binding directly to the ACE and C-boxcis-elements in the promoters of the biosynthetic genesbranched-chain aminotransferase1(OsBCAT1) andOsBCAT2. We further demonstrated thatOsbZIP18is strongly induced by nitrogen (N) deficiency and that N starvation results in enhanced BCAA levels in an OsbZIP18-dependent manner. Overall, we identified OsbZIP18, a positive regulator of BCAA biosynthesis, which contributed to natural variation in BCAA levels and mediated BCAA accumulation throughde novosynthesis by directly modulating the key biosynthetic genesOsBCAT1andOsBCAT2.