Exploiting novel genes to improve resource use efficiency in wheat.

通过减少作物投入(如化肥或杀虫剂)来维持产量，或在作物投入相同或减少的情况下提高产量，可以提高资源利用效率。考虑到确保全球粮食安全的需要和扩大种植面积的有限空间，增加产量可能是最可持续的方法。最近完成的LINK项目(LK0958)确定了染色体3A和7D的区域(称为数量性状基因座或QTL)，这些区域与资源利用效率的提高有关，因为产量增加了0.3至0.4吨/公顷(在给定的作物投入水平上)。在6A染色体上还检测到一个较小的产量效应QTL。这些QTL还与较低的抗倒伏性有关，这主要是由于较高的高度，以及较小的茎壁宽度和根板展开。还发现了其他几个不影响产量的株高QTL。研究还表明，一些株高QTL对植物生长调节剂(PGR)的矮化反应是其他QTL的两倍。这些发现提供了提高资源利用效率的前景，方法是将提高产量的QTL(在给定的投入水平上)与提高抗倒伏能力的QTL结合起来(通过缩短作物)，以及通过更好地瞄准PGR来改善倒伏控制。然而，目前这是不可能的，因为LK0958中确定的遗传标记与QTL区域内的特定基因距离不够近，育种人员无法可靠地识别一系列遗传背景中阳性基因的存在。该项目旨在通过开发可靠的遗传标记和对QTL的生理理解来提高资源利用效率，从而在不增加作物对投入的需求的情况下提高产量和抗倒伏性。这将通过以下方式实现：1)开发仅在染色体区域上存在差异的品种，这些品种将用于实现目标2和3，2)为这些QTL寻找更可靠的遗传标记，3)了解这些QTL的作用机理并量化对资源利用效率和温室气体排放的影响，4)调查当前品种中哪些产量和高度QTL及其组合的范围，以通过提高产量和降低倒伏风险来提高资源利用效率，以及5)量化不同高度QTL对不同PGR活性成分的响应。该项目的一个主要组成部分将涉及克隆3A号染色体上高度/产量QTL内的基因，以产生一个“完美的”遗传标记。将为另一个QTL开发新的标记，由于它们更接近，将具有更高的可靠性。这将允许育种者设计杂交组合，以实现给定杂交的高度和产量QTL的最佳组合。了解QTL影响产量的生理机制(例如，库(粒/平方米)或源(同化物供应)增加)将有助于确定以最少的作物投入实现这些更高产量所需的作物管理措施，从而提高资源利用效率。高度QTL的遗传标记也将被用来预测哪些品种将以不同的作用模式对PGRs反应最大。由于PGRs在大多数小麦作物上预防性使用，这将使它们能够避免在反应迟钝的品种上使用。据估计，该项目将通过更高的产量和更好的倒伏控制，将资源利用效率提高10%。该项目还将补充Defra资助的小麦遗传改良网络(WGIN)，对该网络中产生的近等基因系(NIL)进行表型鉴定，并产生可添加到该网络遗传资源中的新的近等基因系。

Resource use efficiency can be improved by either maintaining yield with lower crop inputs (e.g. fertiliser or pesticides) or increasing yield with the same, or reduced, crop inputs. Increasing yield is likely to be the most sustainable approach given the need to ensure global food security and the limited scope for expanding the cropped area. A recently completed LINK project (LK0958) identified regions of chromosomes 3A and 7D (known as quantitative trait loci or QTL) that were associated with increased resource use efficiency resulting from yield increases of 0.3 to 0.4 t/ha (at a given level of crop inputs). A smaller yield effect QTL was also found on chromosome 6A. These QTL were also associated with a lower resistance to lodging primarily as a result of greater height, and also due to a smaller stem wall width and root plate spread. Several other height QTL were found which did not affect yield. It was also shown that some height QTL were twice as responsive as others to shortening by plant growth regulator (PGR) chemicals. These discoveries offer the prospect of increasing resource use efficiency by combining QTL for increased yield (at a given level of inputs) with QTL for increased lodging resistance (through crop shortening), as well as by improving lodging control through better targeting of PGRs. However this is not currently possible because the genetic markers identified in LK0958 are not close enough to the specific genes located within the QTL region for the breeders to reliably identify the presence of the positive genes in a range of genetic backgrounds. This project aims to increase resource use efficiency by developing reliable genetic markers and a physiological understanding for QTL that increase yield and lodging resistance without increasing the crop's requirement for inputs. This will be achieved by: 1) Developing varieties that differ only for the region of chromosome with the QTL for resource use efficiency (near isogenic lines) which will be used to achieve objectives 2 and 3, 2) Identifying more reliable genetic markers for these QTL, 3) Understanding the physiological mechanisms by which these QTL act and quantifying effects on resource use efficiency and greenhouse gas emissions, 4) Investigating which yield and height QTL are in current varieties and the scope for combining them to increase resource use efficiency through greater yield and reduced lodging risk, and 5) Quantifying the responsiveness of the different height QTL to different PGR active ingredients. A major component of this project will involve cloning the gene within the height/yield QTL on chromosome 3A to produce a 'perfect' genetic marker. New markers will be developed for the other QTL which will have much greater reliability due to their closer proximity. This will allow breeders to design crosses to achieve the optimum combination of height and yield QTL in a given cross. Understanding the physiological mechanisms by which the QTL affect yield (e.g. is sink (grains/m2) or source (supply of assimilate) increased) will help to identify the crop management practices required to achieve these greater yields with minimum crop inputs, and thereby increasing resource use efficiency. Genetic markers for the height QTL will also be used to predict which varieties will respond most to PGRs with different modes of action. As PGRs are used prophylactically on the majority of wheat crops this will allow their use to be avoided on unresponsive varieties. It is estimated that the project will increase resource use efficiency by 10% through greater yields and better lodging control. The project will also complement the Defra funded Wheat Genetic Improvement Network (WGIN) by phenotyping the near isogenic lines (NILs) produced within the network and producing new NILs that can be added to the network's genetic resources.