Linkage analysis of the wheat Wχ genes and quantitative trait loci

本研究旨在明确和探讨小麦同源3个Wχ基因对直链淀粉含量、淀粉结构、淀粉糊化特性和重要农艺性状变异的贡献。结果表明：1）直链淀粉含量从糯性中国春的0%到野生型中国春的25%不等，双无效系的结果进一步证明了直链淀粉合成能力以Wχ-Blα为主，直链淀粉产量为21-22%;其次是Wχ-Dlα（20-21%）和Wχ-Alα（15-18%）。2）8种Wx蛋白缺失株系的支链淀粉结构差异不明显，表明由于无效Wx等位基因的渐渗导致的GBSS I活性降低不影响支链淀粉的分支程度。3）在4A的短臂上定位了一个对直链淀粉含量影响较小的QTL，在4A的短臂上定位了一个对抽穗期影响较小的QTL或与之紧密连锁的QTL。3个Wχ基因座上的无效等位基因对淀粉糊化特性的影响存在差异。Wχ-Blb等位基因的相关效应给出了更高的峰值和击穿粘度，这是明确的，而无效Wχ-Alb的效应小得多。

The present study was carried out to define and discuss the contributions of the homoeologous three Wχ genes of wheat to variation for amylose content, starch structure, starch pasting properties and important agronomic traits. The results obtained from this study are summarized as follows.1) Amylose content varied from 0% of the waxy Chinese Spring (CS) to 25% of the wild-type CS.The results of the double null lines further demonstrated that for the capacity of amylose synthesis, Wχ-Blα predominates and produces 21-22% amylose, followed by Wχ-Dlα (20-21%) and Wχ-Alα (15-18%).2) No clear differences for amylopectin structure were detected among the eight types of the Wx-protein deficient lines, indicating that the reduced GBSS I activity due to introgression of the null Wχ alleles does not affect the degree of branching of amylopectin.3) An additional QTL of a minor effect on amylose content was mapped in the short arm of 4A.An effect of Wχ-Bl or a closely linked QTL on ear emergence time was identified. For plant yield and its components, there was no evidence for significant main effects associated with Wχ-Bl.4) Differential effects of null alleles at the three Wχ loci on starch-pasting properties were revealed. The associated effect of the Wχ-Blb allele giving a higher peak and breakdown viscosity, was unambiguous, while the effects of the null Wχ-Alb are much smaller.