Yang Yingzhen, Labate Joanne A, Liang Zhenchang, Cousins Peter, Prins Bernard, Preece John E, Aradhya Mallikarjuna, Zhong Gan-Yuan
USDA-ARS Grape Genetics Research Unit, Geneva, NY, 14456, USA.
Theor Appl Genet. 2014 Nov;127(11):2433-51. doi: 10.1007/s00122-014-2388-6. Epub 2014 Sep 11.
Wild and loss-of-function alleles of the 5 - O - glucosyltransferase gene responsible for synthesis of diglucoside anthocyanins in Vitis were characterized. The information aids marker development for tracking this gene in grape breeding. Anthocyanins in red grapes are present in two glycosylation states: monoglucoside (3-O-glucoside) and diglucoside (3, 5-di-O-glucoside). While monoglucoside anthocyanins are present in all pigmented grapes, diglucoside anthocyanins are rarely found in the cultivated grape species Vitis vinifera. Biochemically 3-O-glucoside anthocyanins can be converted into 3,5-di-O-glucoside anthocyanins by a 5-O-glucosyltransferase. In this study, we surveyed allelic variation of the 5-O-glucosyltransferase gene (5GT) in 70 V. vinifera ssp. vinifera cultivars, 52 V. vinifera ssp. sylvestris accessions, 23 Vitis hybrid grapes, and 22 accessions of seven other Vitis species. Eighteen 5GT alleles with apparent loss-of-function mutations, including seven premature stop codon mutations and six frameshift indel mutations, were discovered in V. vinifera, but not in the other Vitis species. A total of 36 5GT alleles without apparent loss-of-function mutations (W-type) were identified. These W-type alleles were predominantly present in wild Vitis species, although a few of them were also found in some V. vinifera accessions. We further evaluated some of these 5GT alleles in producing diglucoside anthocyanins by analyzing the content of diglucoside anthocyanins in a set of representative V. vinifera cultivars. Through haplotype network analysis we revealed that V. vinifera ssp. vinifera and its wild progenitor V. vinifera ssp. sylvestris shared many loss-of-function 5GT alleles and extensive divergence of the 5GT alleles was evident within V. vinifera. This work advances our understanding of the genetic diversity of 5GT and provides a molecular basis for future marker-assisted selection for improving this important wine quality trait.
对负责葡萄中二糖苷花青素合成的5 - O - 葡萄糖基转移酶基因的野生型和功能缺失型等位基因进行了表征。这些信息有助于在葡萄育种中开发用于追踪该基因的标记。红葡萄中的花青素以两种糖基化状态存在：单糖苷（3 - O - 葡萄糖苷）和二糖苷（3,5 - 二 - O - 葡萄糖苷）。虽然所有有色葡萄中都存在单糖苷花青素，但在栽培葡萄品种欧洲葡萄（Vitis vinifera）中很少发现二糖苷花青素。从生化角度来看，3 - O - 葡萄糖苷花青素可以通过5 - O - 葡萄糖基转移酶转化为3,5 - 二 - O - 葡萄糖苷花青素。在本研究中，我们调查了70个欧洲葡萄（V. vinifera ssp. vinifera）品种、52个欧洲野生葡萄（V. vinifera ssp. sylvestris）种质、23个葡萄杂交品种以及其他7个葡萄品种的22个种质中5 - O - 葡萄糖基转移酶基因（5GT）的等位基因变异。在欧洲葡萄中发现了18个具有明显功能缺失突变的5GT等位基因，包括7个提前终止密码子突变和6个移码插入缺失突变，而在其他葡萄品种中未发现。共鉴定出36个无明显功能缺失突变的5GT等位基因（W型）。这些W型等位基因主要存在于野生葡萄品种中，不过在一些欧洲葡萄种质中也发现了少数几个。我们通过分析一组代表性欧洲葡萄品种中二糖苷花青素的含量，进一步评估了其中一些5GT等位基因在产生二糖苷花青素方面的作用。通过单倍型网络分析，我们发现欧洲葡萄（V. vinifera ssp. vinifera）及其野生祖先欧洲野生葡萄（V. vinifera ssp. sylvestris）共享许多功能缺失的5GT等位基因，并且在欧洲葡萄中5GT等位基因存在广泛的差异。这项工作增进了我们对5GT基因遗传多样性的理解，并为未来通过标记辅助选择改善这一重要葡萄酒品质性状提供了分子基础。
