FRIZZY PANICLE (FZP) is involved in the development of panicle branching in rice. Herein, a novel mutant fzp-15, demonstrating the sequential rounds of branching and severe defects in SM (spikelet meristem) formation, was identified. Map-based cloning revealed that the abnormal panicle architecture of fzp-15 resulted from an amino acid substitution (Glu (E) to Ala (A)) in the N-terminal ERF domain of rice FZP protein. To generate new advantageous FZP alleles increasing grain numbers, CRISPR/Cas9 multiplex editing system was used to target the 5’ untranslation region (UTR) of FZP in 'Nipponbare' (NIP). The 85-bp (−156 to -72 bp) or 149-bp (−157 to -9 bp) deletion in the upstream region of FZP can significantly increase grain numbers without a decrease in grain size, while the 38-bp deletion (−44 to −7 bp) in the upstream region of FZP has little effect in changing grain numbers. These results indicated that the 113-bp fragment (−157 to −45 bp) upstream of FZP is important to its function and deletion of this region can be used to increase grain numbers in rice.

中文翻译：

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鉴定一种新的突变等位基因 fzp-15，涉及水稻（Oryza sativa）的穗分枝模式

FRIZZY PANICLE ( FZP ) 参与水稻穗分枝的发育。在此，鉴定了一种新的突变体fzp-15，其证明了 SM（小穗分生组织）形成中的分枝和严重缺陷的连续轮次。基于图谱的克隆表明，fzp-15的异常穗结构是由水稻 FZP 蛋白 N 端 ERF 结构域中的氨基酸取代（Glu (E) 到 Ala (A)）引起的。为了产生增加谷物数量的新的有利 FZP等位基因，使用 CRISPR/Cas9 多重编辑系统靶向“日本晴”（NIP）中FZP的 5' 非翻译区（UTR ）。上游区域的 85-bp（-156 至 -72 bp）或 149-bp（-157 至 -9 bp）缺失FZP可以显着增加粒数而不减小粒数，而FZP上游区域的 38-bp 缺失（-44 至 -7 bp）对改变粒数影响不大。这些结果表明FZP上游的 113 bp 片段（-157 至 -45 bp）对其功能很重要，该区域的缺失可用于增加水稻的籽粒数。