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Article|20 Mar 2018|OPEN
Developing gene-tagged molecular markers for evaluation of genetic association of apple SWEET genes with fruit sugar accumulation
Qiaoling Zhen1,2 , Ting Fang1,2 , Qian Peng1,2 and Liao Liao1 , Li Zhao1 , Albert Owiti1,2 , Yuepeng Han,1,3,4 ,
1Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden of the Chinese Academy of Sciences, Wuhan 430074, China
2Graduate University of Chinese Academy of Sciences, 19A Yuquanlu, Beijing 100049, China
3Sino-African Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China
4College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China
*Corresponding author. E-mail: yphan@wbgcas.cn

Horticulture Research 5,
Article number: 14 (2018)
doi: https://doi.org/10.1038/s41438-018-0024-3
Views: 1091

Received: 05 Oct 2017
Revised: 23 Jan 2018
Accepted: 25 Jan 2018
Published online: 20 Mar 2018

Abstract

Sugar content is an important component of fruit quality. Although sugar transporters are known to be crucial for sugar accumulation, the role of genes encoding SWEET sugar transporters in fruit sugar accumulation remains elusive. Here we report the effect of the SWEET genes on fruit sugar accumulation in apple. A total of 25 MdSWEET genes were identified in the apple genome, and 9 were highly expressed throughout fruit development. Molecular markers of these 9 MdSWEET genes were developed and used for genotyping of 188 apple cultivars. The association of polymorphic MdSWEET genes with soluble sugar content in mature fruit was analyzed. Three genes, MdSWEET2e, MdSWEET9b, and MdSWEET15a, were significantly associated with fruit sugar content, with MdSWEET15a and MdSWEET9b accounting for a relatively large proportion of phenotypic variation in sugar content. Moreover, both MdSWEET9b and MdSWEET15a are located on chromosomal regions harboring QTLs for sugar content. Hence, MdSWEET9b and MdSWEET15a are likely candidates regulating fruit sugar accumulation in apple. Our study not only presents an efficient way of implementing gene functional study but also provides molecular tools for genetic improvement of fruit quality in apple-breeding programs.