Olmos S, Distelfeld A, Chicaiza O, Schlatter A R, Fahima T, Echenique V, Dubcovsky J
Department of Agronomy and Range Science, University of California, Davis 95616-8515, USA.
Theor Appl Genet. 2003 Nov;107(7):1243-51. doi: 10.1007/s00122-003-1377-y. Epub 2003 Aug 16.
Grain protein content (GPC) is an important factor in pasta and breadmaking quality, and in human nutrition. It is also an important trait for wheat growers because premium prices are frequently paid for wheat with high GPC. A promising source for alleles to increase GPC was detected on chromosome 6B of Triticum turgidum var. dicoccoides accession FA-15-3 (DIC). Two previous quantitative trait locus (QTL) studies found that the positive effect of DIC-6B was associated to a single locus located between the centromere and the Nor-B2 locus on the short arm of chromosome 6B. Microsatellite markers Xgwm508 and Xgwm193 flanking the QTL region were used in this study to develop 20 new homozygous recombinant substitution lines (RSLs) with crossovers between these markers. These 20 RSLs, plus nine RSLs developed in previous studies were characterized with four new RFLP markers located within this chromosome segment. Grain protein content was determined in three field experiments organized as randomized complete block designs with ten replications each. The QTL peaks for protein content were located in the central region of a 2.7-cM interval between RFLP markers Xcdo365 and Xucw67 in the three experiments. Statistical analyses showed that almost all lines could be classified unequivocally within low- and high- protein groups, facilitating the mapping of this trait as a single Mendelian locus designated Gpc-6B1. The Gpc-6B1 locus was mapped 1.5-cM proximal to Xcdo365 and 1.2-cM distal to Xucw67. These new markers can be used to reduce the size of the DIC chromosome segment selected in marker-assisted selection programs. Markers Nor-B2 and Xucw66 flanking the previous two markers can be used to select against the DIC segment and reduce the linkage drag during the transfer of Gpc-6B1 into commercial bread and pasta wheat varieties. The precise mapping of the high GPC gene, the high frequency of recombinants recovered in the targeted region, and the recent development of a tetraploid BAC library including the Gpc-6B1 DIC allele are the first steps towards the map-based cloning of this gene.
谷物蛋白质含量（GPC）是影响意大利面和面包制作品质以及人类营养的重要因素。对于小麦种植者来说，它也是一个重要性状，因为高蛋白含量的小麦通常能卖高价。在四倍体野生二粒小麦（Triticum turgidum var. dicoccoides）种质FA - 15 - 3（DIC）的6B染色体上，发现了一个有望增加GPC的等位基因来源。此前的两项数量性状位点（QTL）研究发现，DIC - 6B的正向效应与位于6B染色体短臂着丝粒和Nor - B2位点之间的一个单一位点有关。本研究使用位于QTL区域两侧的微卫星标记Xgwm508和Xgwm193，培育了20个在这些标记之间发生交换的新的纯合重组代换系（RSL）。这20个RSL，加上之前研究中培育的9个RSL，用位于该染色体区段内的4个新的RFLP标记进行了特征分析。在3个田间试验中测定了谷物蛋白质含量，试验采用随机完全区组设计，每个试验重复10次。在这三个试验中，蛋白质含量的QTL峰值位于RFLP标记Xcdo365和Xucw67之间2.7厘摩区间的中部。统计分析表明，几乎所有品系都能明确地分为低蛋白组和高蛋白组，便于将该性状定位为一个单孟德尔位点，命名为Gpc - 6B1。Gpc - 6B1位点定位在Xcdo365近端1.5厘摩处，Xucw67远端1.2厘摩处。这些新标记可用于缩小标记辅助选择计划中所选DIC染色体区段的大小。位于前两个标记两侧的标记Nor - B2和Xucw66可用于排除DIC区段，减少将Gpc - 6B1导入商业面包和意大利面小麦品种过程中的连锁累赘。高GPC基因的精确图谱绘制、在目标区域获得的高频率重组体以及包含Gpc - 6B1 DIC等位基因的四倍体BAC文库的最新构建，是该基因基于图谱克隆的第一步。
