Butow B J, Ma W, Gale K R, Cornish G B, Rampling L, Larroque O, Morell M K, Békés F
CSIRO Plant Industry, GPO Box 1600, Canberra 2601, ACT, Australia.
Theor Appl Genet. 2003 Nov;107(8):1524-32. doi: 10.1007/s00122-003-1396-8. Epub 2003 Sep 6.
High-molecular-weight glutenin subunits (HMW-GS) are important determinants of wheat dough quality as they confer visco-elastic properties to the dough required for mixing and baking performance. With this important role, the HMW-GS alleles are key markers in breeding programs. In this work, we present the use of a PCR marker initially designed to discriminate Glu1 Bx7 and Glu1 Bx17 HMW-GS. It was discovered that this marker also differentiated two alleles, originally both scored as Glu1 Bx7, present in the wheat lines CD87 and Katepwa respectively, by a size polymorphism of 18 bp. The marker was scored across a segregating doubled-haploid (DH) population (CD87 x Katepwa) containing 156 individual lines and grown at two sites. Within this population, the marker differentiated lines showing the over-expression of the Glu1 Bx7 subunit (indicated by the larger PCR fragment), derived from the CD87 parent, relative to lines showing the normal expression of the Glu1 Bx7 subunit, derived from the Katepwa parent. DNA sequence analysis showed that the observed size polymorphism was due to an 18 bp insertion/deletion event at the C-terminal end of the central repetitive domain of the Glu1 Bx 7 coding sequence, which resulted in an extra copy of the hexapeptide sequence QPGQGQ in the deduced amino-acid sequence of Bx7 from CD87. When the DH population was analysed using this novel Bx7 PCR marker, SDS PAGE and RP HPLC, there was perfect correlation between the Bx7 PCR marker results and the expression level of Bx7. This differentiation of the population was confirmed by both SDS-PAGE and RP-HPLC. The functional significance of this marker was assessed by measuring key dough properties of the 156 DH lines. A strong association was shown between lines with an over expression of Bx7 and high dough strength. Furthermore, the data demonstrated that there was an additional impact of Glu-D1 alleles on dough properties, with lines containing both over-expressed Bx7 and Glu-D1 5+10 having the highest levels of dough strength. However, there was no statistically significant epistatic interaction between Glu-B1 and Glu-D1 loci.
高分子量谷蛋白亚基（HMW-GS）是小麦面团品质的重要决定因素，因为它们赋予面团混合和烘焙性能所需的粘弹性。鉴于这一重要作用，HMW-GS等位基因是育种计划中的关键标记。在本研究中，我们展示了一种最初设计用于区分Glu1 Bx7和Glu1 Bx17 HMW-GS的PCR标记的应用。结果发现，该标记还通过18 bp的大小多态性区分了分别存在于小麦品系CD87和Katepwa中的两个最初都被记为Glu1 Bx7的等位基因。该标记在包含156个单株系且在两个地点种植的分离双单倍体（DH）群体（CD87×Katepwa）中进行评分。在这个群体中，该标记区分了来自CD87亲本、显示Glu1 Bx7亚基过表达（由较大的PCR片段指示）的株系和来自Katepwa亲本、显示Glu1 Bx7亚基正常表达的株系。DNA序列分析表明，观察到的大小多态性是由于Glu1 Bx 7编码序列中心重复结构域C末端的18 bp插入/缺失事件，这导致CD87的Bx7推导氨基酸序列中六肽序列QPGQGQ出现额外拷贝。当使用这种新型Bx7 PCR标记、SDS-PAGE和RP HPLC分析DH群体时，Bx7 PCR标记结果与Bx7表达水平之间存在完美的相关性。SDS-PAGE和RP-HPLC均证实了该群体的这种区分。通过测量156个DH系的关键面团特性来评估该标记的功能意义。结果表明，Bx7过表达的株系与高面团强度之间存在强关联。此外，数据表明Glu-D1等位基因对面团特性还有额外影响，同时含有过表达Bx7和Glu-D1 5+10的株系具有最高水平的面团强度。然而，Glu-B1和Glu-D1位点之间没有统计学上显著的上位性相互作用。
