Flower and fruit development are two key steps for plant reproduction. The ABCE model for flower development has been well established in model plant species; however, the functions of ABCE genes in fruit crops are less understood. In this work, we identified an EMS mutant named R27 in woodland strawberry (Fragaria vesca), showing the conversion of petals, stamens, and carpels to sepaloid organs in a semidominant inheritance fashion. Mapping by sequencing revealed that the class E gene homolog FveSEP3 (FvH4_4g23530) possessed the causative mutation in R27 due to a G to E amino acid change in the conserved MADS domain. Additional fvesep3CR mutants generated by CRISPR/Cas9 displayed similar phenotypes to fvesep3-R27. Overexpressing wild-type or mutated FveSEP3 in Arabidopsis suggested that the mutation in R27 might cause a dominant-negative effect. Further analyses indicated that FveSEP3 physically interacted with each of the ABCE proteins in strawberry. Moreover, both R27 and fvesep3CR mutants exhibited parthenocarpic fruit growth and delayed fruit ripening. Transcriptome analysis revealed that both common and specific differentially expressed genes were identified in young fruit at 6–7 days post anthesis (DPA) of fvesep3 and pollinated wild type when compared to unpollinated wild type, especially those in the auxin pathway, a key hormone regulating fruit set in strawberry. Together, we provided compelling evidence that FveSEP3 plays predominant E functions compared to other E gene homologs in flower development and that FveSEP3 represses fruit growth in the absence of pollination and promotes fruit ripening in strawberry.

中文翻译：

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MADS-box基因FveSEP3在林地草莓花器官发生和果实发育中起重要作用

花和果实的发育是植物繁殖的两个关键步骤。花卉发育的 ABCE 模型已经在模式植物物种中得到了很好的建立；然而，人们对水果作物中 ABCE 基因的功能知之甚少。在这项工作中，我们在林地草莓中发现了一个名为 R27 的 EMS 突变体（草莓)，显示花瓣、雄蕊和心皮以半显性遗传方式向萼片器官的转化。通过排序映射显示该类乙基因同源物FveSEP3（FvH4_4g23530）由于保守的 MADS 结构域中的 G 到 E 氨基酸变化而在 R27 中具有致病突变。额外的fvesep3铬由 CRISPR/Cas9 产生的突变体显示出与fvesep3-R27. 过度表达野生型或突变型FveSEP3在拟南芥中的研究表明，R27 中的突变可能会导致显性负效应。进一步的分析表明，FveSEP3 与草莓中的每种 ABCE 蛋白发生物理相互作用。此外，R27 和fvesep3铬突变体表现出单性结实的果实生长和延迟果实成熟。转录组分析显示，在开花后 6-7 天（DPA）的幼果中发现了常见和特异性差异表达基因。fvesep3与未授粉的野生型相比，授粉的野生型尤其是生长素途径中的那些，这是一种调节草莓坐果的关键激素。我们一起提供了令人信服的证据，证明FveSEP3与花发育中的其他 E 基因同源物相比，发挥主要的 E 功能，并且FveSEP3在没有授粉的情况下抑制果实生长并促进草莓果实成熟。