The OsNAC23-Tre6P-SnRK1a feed-forward loop regulates sugar homeostasis and grain yield in rice
The OsNAC23-Tre6P-SnRK1a feed-forward loop regulates sugar homeostasis and grain yield in rice
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OsNAC23-Tre6P-SnRK1a 前馈回路调节水稻的糖稳态和谷物产量。
DOI：
10.1016/j.molp.2022.01.016
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发表时间：
2022-04-06
期刊：
影响因子：
27.5
通讯作者：
Zhang, Jian
中科院分区：
文献类型：
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作者：
Li, Zhiyong;Wei, Xiangjin;Zhang, Jian
Tre6P(海藻糖-6-磷酸)介导碳有效性的感知，以维持植物中糖的动态平衡，这是作物产量和弹性的基础。然而，Tre6P如何对糖水平的波动做出反应并调节糖的利用以促进生长仍有待解决。在这里，我们报道了糖诱导的水稻NAC转录因子OsNAC23直接抑制Tre6P磷酸酶基因TPP1的转录，同时上调Tre6P和抑制海藻糖水平，从而促进碳从源到库器官的分配。同时，OsNAC23和Tre6P抑制OsNAC23的低碳感受器和拮抗剂SnRK1a的转录和酶活性，从而阻止SnRK1a介导的磷酸化和OsNAC23的降解。因此，OsNAC23、Tre6P和SnRK1a形成了一个前馈环，通过将糖运输到下沉器官来感知糖并维持糖的动态平衡。重要的是，过表达OsNAC23的植株表现出更高的光合作用速率、糖运输和库器大小，这在三个优良品种背景和两个地点持续增加水稻产量13%-17%，这表明操纵OsNAC23表达在水稻改良方面具有巨大的潜力。总之，这些发现加深了我们对Tre6P介导的糖信号和动态平衡的理解，并为水稻和其他作物的遗传改良提供了一种新的策略。
Tre6P (trehalose-6-phosphate) mediates sensing of carbon availability to maintain sugar homeostasis in plants, which underpins crop yield and resilience. However, how Tre6P responds to fluctuations in sugar levels and regulates the utilization of sugars for growth remains to be addressed. Here, we report that the sugar-inducible rice NAC transcription factor OsNAC23 directly represses the transcription of the Tre6P phosphatase gene TPP1 to simultaneously elevate Tre6P and repress trehalose levels, thus facilitating carbon partitioning from source to sink organs. Meanwhile, OsNAC23 and Tre6P suppress the transcription and enzyme activity of SnRK1a, a low-carbon sensor and antagonist of OsNAC23, to prevent the SnRK1a-mediated phosphorylation and degradation of OsNAC23. Thus, OsNAC23, Tre6P, and SnRK1a form a feed-forward loop to sense sugar and maintain sugar homeostasis by transporting sugars to sink organs. Importantly, plants over-expressing OsNAC23 exhibited an elevated photosynthetic rate, sugar transport, and sink organ size, which consistently increased rice yields by 13%-17% in three elite-variety backgrounds and two locations, suggesting that manipulation of OsNAC23 expression has great potential for rice improvement. Collectively, these findings enhance our understanding of Tre6P-mediated sugar signaling and homeostasis, and provide a new strategy for genetic improvement of rice and possibly also other crops.