Fruit colour affects consumer preference and is an important trait for breeding in strawberry. Previously, we isolated the Reduced Anthocyanins in Petioles (RAP ) gene encoding a glutathione S‐transferase (GST) that binds anthocyanins to facilitate their transport from cytosol to vacuole in the diploid strawberry Fragaria vesca . The parent of rap was the F. vesca variety ‘Yellow Wonder’ that develops white fruit due to a natural mutation in the FveMYB10 gene. Here, we investigated the application potential of RAP in modulating fruit colours by overexpression of RAP in F. vesca and knockout of RAP in the cultivated strawberry Fragaria × ananassa . Unexpectedly, the RAP overexpression in Yellow Wonder background caused formation of red fruit. In addition, the red coloration occurs precociously at floral stage 10 and continues in the receptacle during early fruit development. Transcriptome analysis revealed that the anthocyanin biosynthesis genes were not up‐regulated in RAP‐ox; rap myb10 flowers at anthesis and largely inhibited at the turning stage in fruit, suggesting a coloration mechanism independent of FveMYB10 . Moreover, we used CRISPR/Cas9 to knockout RAP in cultivated strawberry which is octoploid. Six copies of RAP were simultaneously knocked out in the T0 generation leading to the green stem and white‐fruited phenotype. Several T1 progeny have segregated away the CRISPR/Cas9 transgene but maintain the green stem trait. Our results indicate that enhancing the anthocyanin transport could redirect the metabolic flux from proanthocyanidin to anthocyanin production at early developmental stages of fruit and that RAP is one promising candidate gene in fruit colour breeding of strawberry.

中文翻译：

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RAP 的基因调节会改变野生和栽培草莓的果实颜色。


果实颜色影响消费者的偏好，是草莓育种的重要性状。此前，我们分离出了叶柄中花青素减少（ RAP ）基因，该基因编码谷胱甘肽S-转移酶（GST），该酶与花青素结合，促进二倍体草莓草莓中花青素从细胞质转运至液泡。 rap的亲本是F. vesca品种“Yellow Wonder”，由于FveMYB10基因的自然突变，该品种可结出白色果实。在这里，我们通过在F. vesca中过表达RAP和在栽培草莓Fragaria × ananassa中敲除RAP ，研究了RAP在调节果实颜色方面的应用潜力。出乎意料的是，在Yellow Wonder背景下RAP的过度表达导致了红色果实的形成。此外，红色在花期 10 出现得较早，并在早期果实发育过程中在花托中持续。转录组分析表明， RAP-ox 中花青素生物合成基因并未上调； rap myb10在花期开花，并在果实的转折期很大程度上受到抑制，这表明其着色机制不依赖于FveMYB10 。此外，我们使用CRISPR/Cas9敲除八倍体栽培草莓中的RAP 。在 T0 代中，六个RAP拷贝同时被敲除，导致绿色茎和白色果实的表型。一些 T1 后代已经分离出 CRISPR/Cas9 转基因，但保留了绿色茎特征。 我们的结果表明，增强花青素运输可以在果实早期发育阶段将代谢流从原花青素转向花青素生产，并且RAP是草莓果实颜色育种中一个有前途的候选基因。