Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.
College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
J Exp Bot. 2018 Apr 27;69(10):2595-2608. doi: 10.1093/jxb/ery096.
The red color of the foliage and fruit in strawberry comes from anthocyanins stored in the vacuole; however, how this anthocyanin accumulation is regulated remains unclear. A reduced anthocyanin in petioles (rap) mutant was identified in an N-ethyl-N-nitrosourea (ENU) mutagenized population of YW5AF7, a white-fruited variety of the wild strawberry Fragaria vesca. The causative mutation was identified to be a premature stop codon in a glutathione S-transferase (GST) gene. In addition to the foliage coloration, RAP also mediates fruit pigmentation and acts downstream of the fruit-specific transcription factor FvMYB10. Among all eight GST genes in the same subfamily, RAP is most abundantly expressed in the ripening fruit. Expression analysis and transient expression assays demonstrated that RAP is the principal transporter of anthocyanins among the paralogs. Moreover, domain-swap experiments showed that both the N- and C-terminals of RAP are essential for the binding capability of anthocyanins. In addition, transient knock-down of RAP resulted in reduced fruit coloration in cultivated strawberry. Collectively, our results demonstrate that RAP encodes the principal GST transporter of anthocyanins in the strawberry foliage and fruit, and it could be modified to alter the fruit color in strawberry.
草莓叶片和果实的红色来自于液泡中储存的花青素；然而，这种花青素积累是如何调节的仍然不清楚。在 YW5AF7 的 N-乙基-N-亚硝基脲（ENU）诱变群体中，发现了一个叶柄花青素减少（rap）突变体，YW5AF7 是野生草莓 Fragaria vesca 的一个白肉品种。该突变的原因是谷胱甘肽 S-转移酶（GST）基因的提前终止密码子。除了叶片颜色，RAP 还介导了果实色素沉着，并作用于果实特异性转录因子 FvMYB10 的下游。在同一亚家族的八个 GST 基因中，RAP 在成熟果实中的表达最丰富。表达分析和瞬时表达实验表明，RAP 是同系物中花青素的主要转运蛋白。此外，结构域交换实验表明，RAP 的 N-和 C-末端对于花青素的结合能力都是必不可少的。此外，RAP 的瞬时敲低导致栽培草莓果实颜色变浅。总之，我们的结果表明，RAP 编码草莓叶片和果实中花青素的主要 GST 转运蛋白，并且可以通过修饰来改变草莓的果实颜色。
