Transcriptional silencer and copy number variants (CNVs) are associated with gene expression. However, their roles in generating phenotypes have not been well studied. Here we identified a rice quantitative trait locus, SGDP7 (Small Grain and Dense Panicle 7). SGDP7 is identical to FZP (FRIZZY PANICLE), which represses the formation of axillary meristems. The causal mutation of SGDP7 is an 18-bp fragment, named CNV-18bp, which was inserted ~5.3 kb upstream of FZP and resulted in a tandem duplication in the cultivar Chuan 7. The CNV-18bp duplication repressed FZP expression, prolonged the panicle branching period and increased grain yield by more than 15% through substantially increasing the number of spikelets per panicle (SPP) and slightly decreasing the 1,000-grain weight (TGW). The transcription repressor OsBZR1 binds the CGTG motifs in CNV-18bp and thereby represses FZP expression, indicating that CNV-18bp is the upstream silencer of FZP. These findings showed that the silencer CNVs coordinate a trade-off between SPP and TGW by fine-tuning FZP expression, and balancing the trade-off could enhance yield potential.
SGDP7與FZP等位，能抑制腋生分生組織的形成。SGDP7突變是一個(gè)18bp的片段，名為CNV-18bp，插入FZP上游約5.3kb，導(dǎo)致川7號(hào)的串聯(lián)重復(fù)。CNV-18bp重復(fù)抑制了FZP表達(dá)，延長(zhǎng)了穗分枝期，顯著增加了每穗穎花數(shù)，使千粒重略有下降，籽粒產(chǎn)量提高了15%以上。轉(zhuǎn)錄抑制因子OsBZR1與CNV-18bp中的CGTG基序結(jié)合，從而抑制FZP表達(dá)，表明CNV-18bp是FZP的上游沉默因子。這些結(jié)果表明，沉默因子CNVs通過(guò)微調(diào)FZP表達(dá)來(lái)協(xié)調(diào)每穗穎花數(shù)和前粒重之間的平衡，可以提高產(chǎn)量潛力。