Maximising the potential of Aegilops ventricosa introgression for Pch1 eyespot resistance and increased grain protein in wheat

纹枯病是英国最重要的谷类茎基病害，每年造成1200-2000万GB的产量损失，此外还有大量的杀菌剂支出。目前已知现代小麦品种中只有三个抗纹枯病的来源。其中最有效的是Pch1基因，它起源于一种野草。这种抗性是通过常规杂交的方式引入小麦的，用来自野草的相当部分(所谓的7DV片段)取代了小麦的一条染色体的很大一段。另外两个抗纹枯病品种(Pch2和QTL5A)都来自品种Cappelle Desprez，但它们对纹枯病的抗性都只有温和的影响。携带7DV片段的小麦品种对纹枯病具有高度的抗性，也观察到含有7DV片段的品种具有更高的籽粒蛋白质含量。不幸的是，携带这个7DV片段的品种遭受了产量损失，而且直到最近，携带Pch1的品种才被开发出来，这些品种也具有高产潜力。我们发现，这些品种大多携带完整的原始片段，因此7DV片段的负产量效应似乎被这些新品种中的其他因素所补偿。将理想的纹枯病抗性和蛋白质含量性状从有害的产量效应中分离出来的努力受到两个因素的严重阻碍：地方小麦染色体与7DV片段之间的重组明显减少，以及缺乏合适的DNA标记。然而，标记技术的最新进展使鉴定7DV片段和识别携带小得多片段的品系成为可能。在这个项目中，我们的目标是分离Pch1基因，并鉴定7DV片段中导致籽粒蛋白质含量增加的部分。这将使植物育种者能够培育出携带7DV片段的理想部分(Pch1抗纹枯病和导致籽粒蛋白质含量增加的部分)的小麦品种，而不携带不受欢迎的部分(产量损失)。Pch1位于7DV的区域，与来自Cappelle Desprez的中等有效的抗纹枯病基因Pch2相似。这两种抗性可能是由于姐妹基因造成的，我们将确定是否如此，或者它们是否处于相似但不相同的位置。

Eyespot is the most important disease of the stem base of cereals in the UK causing £12-20 million per annum in lost yield, in addition to significant expenditure on fungicides. Only three sources of resistance to eyespot are known to be present in modern wheat cultivars. The most potent of these is the gene Pch1, which originates from a wild grass. This resistance was introduced into wheat by conventional crossing, replacing a large segment of one of the wheat chromosomes with the equivalent portion from the wild grass (so-called 7DV segment). The two other eyespot resistances (Pch2 and QTL5A) both come from the variety Cappelle Desprez but they both have only moderate effects on eyespot resistance. Wheat varieties carrying the 7DV segment are highly resistant to eyespot and it has also been observed that varieties containing the 7DV segment have a higher grain protein content. Unfortunately varieties carrying this 7DV segment suffer a yield penalty and it is only relatively recently that Pch1 carrying varieties have been developed that also possess high yield potential. We have shown that most of these varieties carry the full size original segment and so it appears that the negative yield effect of the 7DV segment is compensated by other factors in these new varieties.Efforts to separate the desirable eyespot resistance and protein content traits from the deleterious yield effect have been seriously hindered by two factors: an apparent reduction in recombination between the native wheat chromosome and the 7DV segment and a lack of suitable DNA markers. However, recent advances in marker technology have made it possible to characterise the 7DV segment and identify lines carrying much smaller segments. In this project we aim to isolate the Pch1 gene and also identify the part of the7DV segment that confers the increased grain protein content. This will enable plant breeders to develop wheat varieties that carry the desirable parts of the 7DV segment (Pch1 eyespot resistance and the part responsible for increased grain protein content) without the undesirable (yield penalty) parts.Pch1 lies in a region of 7DV that is similar to that of the moderately effective eyespot resistance gene Pch2 from Cappelle Desprez. These two resistances are potentially due to 'sister' genes and we will determine whether this is the case or whether they are in similar but not identical positions.