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Article|27 Jul 2020|OPEN
The sugar transporter system of strawberry: genome-wide identification and expression correlation with fruit soluble sugar-related traits in a Fragaria × ananassa germplasm collection
Hai-Ting Liu1,2, Ying Ji1,2, Ya Liu1, Shu-Hua Tian1, Qing-Hua Gao1,2,, Xiao-Hua Zou1, Jing Yang1, Chao Dong1, Jia-Hui Tan1,3, Di-An Ni2 & Ke Duan1,
1Shanghai Key Laboratory of Protected Horticultural Technology, Forestry and Fruit Tree Research Institute, Shanghai Academy of Agricultural Sciences (SAAS), Shanghai 201403, China
2Ecological Technique and Engineering College, Shanghai Institute of Technology, Shanghai 201418, China
3Environmental Engineering College, Suzhou Polytechnic Institute of Agriculture, Suzhou 215008, China

Horticulture Research 7,
Article number: 132 (2020)
doi: 10.1038/hortres.2020.132
Views: 423

Received: 24 Feb 2020
Revised: 02 Jun 2020
Accepted: 04 Jun 2020
Published online: 27 Jul 2020

Abstract

Sugar from plant photosynthesis is a basic requirement for life activities. Sugar transporters are the proteins that mediate sugar allocation among or within source/sink organs. The transporters of the major facilitator superfamily (MFS) targeting carbohydrates represent the largest family of sugar transporters in many plants. Strawberry (Fragaria × ananassa Duchesne) is an important crop appreciated worldwide for its unique fruit flavor. The involvement of MFS sugar transporters (STs) in cultivated strawberry fruit sugar accumulation is largely unknown. In this work, we characterized the genetic variation associated with fruit soluble sugars in a collection including 154 varieties. Then, a total of 67 ST genes were identified in the v4.0 genome integrated with the v4.0.a2 protein database of F. vesca, the dominant subgenome provider for modern cultivated strawberry. Phylogenetic analysis updated the nomenclature of strawberry ST homoeologs. Both the chromosomal distribution and structural characteristics of the ST family were improved. Semi-RT-PCR analysis in nine tissues from cv. Benihoppe screened 34 highly expressed ST genes in fruits. In three varieties with dramatically differing fruit sugar levels, qPCR integrated with correlation analysis between ST transcript abundance and sugar content identified 13 sugar-correlated genes. The correlations were re-evaluated across 19 varieties, including major commercial cultivars grown in China. Finally, a model of the contribution of the sugar transporter system to subcellular sugar allocation in strawberry fruits was proposed. Our work highlights the involvement of STs in controlling strawberry fruit soluble sugars and provides candidates for the future functional study of STs in strawberry development and responses and a new approach for strawberry genetic engineering and molecular breeding.