Marcotuli Ilaria, Houston Kelly, Waugh Robbie, Fincher Geoffrey B, Burton Rachel A, Blanco Antonio, Gadaleta Agata
Department of Soil, Plant and Food Sciences, Section of Genetics and Plant Breeding, University of Bari 'Aldo Moro', Via G. Amendola 165/A, Bari, Italy.
The James Hutton Institute, Invergowrie, Dundee, Scotland.
PLoS One. 2015 Jul 15;10(7):e0132787. doi: 10.1371/journal.pone.0132787. eCollection 2015.
Arabinoxylans (AXs) are major components of plant cell walls in bread wheat and are important in bread-making and starch extraction. Furthermore, arabinoxylans are components of soluble dietary fibre that has potential health-promoting effects in human nutrition. Despite their high value for human health, few studies have been carried out on the genetics of AX content in durum wheat.
The genetic variability of AX content was investigated in a set of 104 tetraploid wheat genotypes and regions attributable to AX content were identified through a genome wide association study (GWAS). The amount of arabinoxylan, expressed as percentage (w/w) of the dry weight of the kernel, ranged from 1.8% to 5.5% with a mean value of 4.0%. The GWAS revealed a total of 37 significant marker-trait associations (MTA), identifying 19 quantitative trait loci (QTL) associated with AX content. The highest number of MTAs was identified on chromosome 5A (seven), where three QTL regions were associated with AX content, while the lowest number of MTAs was detected on chromosomes 2B and 4B, where only one MTA identified a single locus. Conservation of synteny between SNP marker sequences and the annotated genes and proteins in Brachypodium distachyon, Oryza sativa and Sorghum bicolor allowed the identification of nine QTL coincident with candidate genes. These included a glycosyl hydrolase GH35, which encodes Gal7 and a glucosyltransferase GT31 on chromosome 1A; a cluster of GT1 genes on chromosome 2B that includes TaUGT1 and cisZog1; a glycosyl hydrolase that encodes a CelC gene on chromosome 3A; Ugt12887 and TaUGT1genes on chromosome 5A; a (1,3)-β-D-glucan synthase (Gsl12 gene) and a glucosyl hydrolase (Cel8 gene) on chromosome 7A.
This study identifies significant MTAs for the AX content in the grain of tetraploid wheat genotypes. We propose that these may be used for molecular breeding of durum wheat varieties with higher soluble fibre content.
阿拉伯木聚糖（AXs）是面包小麦中植物细胞壁的主要成分，在面包制作和淀粉提取中起着重要作用。此外，阿拉伯木聚糖是可溶性膳食纤维的组成部分，在人类营养中具有潜在的促进健康的作用。尽管它们对人类健康具有很高的价值，但关于硬粒小麦中AX含量的遗传学研究却很少。
在一组104个四倍体小麦基因型中研究了AX含量的遗传变异性，并通过全基因组关联研究（GWAS）确定了与AX含量相关的区域。以籽粒干重的百分比（w/w）表示的阿拉伯木聚糖含量范围为1.8%至5.5%，平均值为4.0%。GWAS共揭示了37个显著的标记-性状关联（MTA），确定了19个与AX含量相关的数量性状位点（QTL）。在5A染色体上鉴定出的MTA数量最多（7个），其中三个QTL区域与AX含量相关，而在2B和4B染色体上检测到的MTA数量最少，其中只有一个MTA鉴定出一个单一基因座。SNP标记序列与短柄草、水稻和高粱中注释的基因和蛋白质之间的共线性保守性使得能够鉴定出9个与候选基因一致的QTL。这些基因包括：1A染色体上编码Gal7的糖基水解酶GH35和葡糖基转移酶GT31；2B染色体上包括TaUGT1和顺式Zog1的GT1基因簇；3A染色体上编码CelC基因的糖基水解酶；5A染色体上的Ugt12887和TaUGT1基因；7A染色体上的（1,3）-β-D-葡聚糖合酶（Gsl12基因）和葡糖基水解酶（Cel8基因）。
本研究确定了四倍体小麦基因型籽粒中AX含量的显著MTA。我们建议这些可用于分子育种，培育具有更高可溶性纤维含量的硬粒小麦品种。
