Duplication of an upstream silencer of FZP significantly increases grain yield in rice (Abstract)

Document Type : Original Article

Author

National Key Lab of Crop Genetic improvement, Huahzong Agricultural University, 430070, Wuhan China

Abstract

Transcriptional silencer and copy number variants (CNVs) are associated with gene expression. However, their roles in generating phenotypes have not been well studied. In this study, we identified a rice quantitative trait locus (QTL), SGDP7 (Small Grain and Dense Panicle 7). SGDP7 is identical to FZP (FRIZZLE PANICLE), which represses the formation of axillary meristems. An 18-bp fragment, named CNV-18bp, was inserted ~5.3 kb upstream of FZP, thus resulting in a tandem duplication in Chuan 7. The CNV-18bp duplication repressed FZP expression, prolonged the panicle branching period and increased grain yield by more than 15% by substantially increasing the number of spikelets per panicle (SPP) and slightly decreasing 1000-grain weight (TGW). The transcription repressor OsBZR1 binds the CGTG motifs in CNV-18bp and represses FZP expression, indicating that CNV-18bp is the upstream silencer of FZP. These findings showed that CNVs of the silencer coordinate a trade-off between SPP and TGW by fine-tuning FZP expression, and balancing the trade-off would enhance yield potential. 

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