RAP codes for a GST anthocyanin transporter that is essential for the foliage and fruit coloration in strawberry 

First author: Huifeng Luo; Affiliations: Huazhong Agricultural University (华中农业大学): Wuhan, China

Corresponding author: Chunying Kang

The red color of the foliage (枝叶) and fruit in strawberry comes from anthocyanins (花青素) stored in the vacuole (液泡). However, how anthocyanin accumulation is regulated in strawberry is still unclear. A reduced anthocyanin in petioles (rap) mutant was identified in an ENU (乙烷基亚硝基脲) mutagenized population of YW5AF7, a white-fruited variety of the wild strawberry Fragaria vesca. The causative mutation was identified to be a premature (提前的) stop codon in a glutathione S-transferase (GST; 谷胱甘肽S-转移酶) gene. In addition to the foliage coloration, RAP also mediates fruit pigmentation (色素沉着) 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 (瞬时表达) assay demonstrated that RAP is the principal transporter of anthocyanins among the paralogs. Moreover, domain swap experiments (结构域交换试验) showed that both N- and C-termini 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 could be modified to alter the fruit color in strawberry.

草莓枝叶和果实的红色是源自于储存在液泡中的花青素。然而，草莓中花青素的积累是由什么机制所调控的仍然不清楚。作者从野草莓白色果实品种YW5AF7的乙烷基亚硝基脲诱变群体中鉴定到了一个叶柄中花青素积累减少的突变体（rap）。经过鉴定，该突变体是由于一个谷胱甘肽S-转移酶基因发生提前终止的突变所导致的。另外，除了枝叶的着色，RAP同时还调控果实的色素沉着，并且在果实特异转录因子FvMYB10的下游发挥作用。在同一个亚家族所有的八个GST基因中，RAP基因是在成熟的果实中表达量最高的。表达分析和瞬时表达分析显示RAP是所有旁系同源中最主要的花青素转运蛋白。此外，结构域交换试验显示RAP的N端和C端对于其与花青素的结合能力均是必要的。综上，本文的研究结果表明在草莓的枝叶和水果中，RAP编码的蛋白是花青素主要的转运体，可以作为将来改变草莓果实颜色的靶基因。

通讯：康春颖 (http://chfs.hzau.edu.cn/info/1028/1127.htm)

个人简历：2004年，中国农业大学，生物科学学士；2010年，中国科学院上海植物生理生态研究所，博士，方向：拟南芥中气孔发育的光信号调控机制研究；2010年，美国马里兰大学帕克分校，博士后，方向：采用生物信息学手段研究森林草莓花发育和果实早期发育的分子机理。

研究方向：利用二倍体草莓作为蔷薇科的模式植物，采用正向和反向遗传学及生物信息学等手段对果实发育分子调控机理开展深入研究。

doi: https://doi.org/10.1093/jxb/ery096

Journal: Journal of Experimental Botany

Published date: 10 March, 2018

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