Title : Sugar-inducible rice nac transcription factors regulates carbon partitioning and grain yield
Abstract:
Tre6P (trehalose-6-phosphate) senses carbon availability to maintain sugar homeostasis in plants, which underpins crop yield and resilience. However, how Tre6P responds to fluctuations in sugar levels and utilizes sugars for growth remains to be addressed. Here, we report that the sugar-inducible rice 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-SnRK1a forms a feed-forward loop to sense sugar and maintain sugar homeostasis by transporting sugars to sink organs. Importantly, plants over-expressing OsNAC23 (to optimize the source-sink interaction) showed an elevated photosynthetic rate, sugar transport, and sink organ size, which consistently increased rice yields by 13-17% in multiple elite variety backgrounds, locations, and years, showing great potential for the genetic improvement of crops. These findings enhance our understanding of Tre6P-mediated sugar signaling and homeostasis and provide a new strategy for the genetic improvement of crops.
