Optimising wheat grain shape and size for improved processing quality.

碾磨是将小麦磨成面粉的过程，在此过程中，小麦被分成不同的部分：外层（麸皮）、胚芽（胚芽）和胚乳（白面粉）。碾磨小麦或大麦是特别困难的，因为谷物的形状不规则：不像大米或多或少是圆柱形的，小麦和大麦有一个深槽或折痕在一个表面；这使得从胚乳外层分离的问题。不同的小麦品种生产不同类型的面粉，用于制作面包或饼干，但从每种谷物中提取的面粉量也不同。研究表明，每粒谷物的面粉产量取决于谷物的大小和形状，因为这决定了被胚乳吸收的谷物相对于其他谷物部分的比例。此外，随着最近面粉厂对去皮（去除外层）的采用，折痕的形状和深度对面粉提取的重要性变得非常重要。育种者经常选择新品种来提高粮食产量，其中一个组成部分是粮食的大小，但以前没有专门选择粮食形状。该项目旨在调查不同小麦品种中存在的不同晶粒尺寸和折痕形状的范围，并将它们与碾磨产量联系起来。籽粒形状对用于发芽的大麦也很重要，因为短而肥的籽粒是可取的，因为这允许存在于胚乳中的淀粉更快地被用作发芽胚胎的食物。生长在印度和巴基斯坦的一种古老的小麦亚种，有很小的球形颗粒，有很浅的折痕；我们的部分工作将是评估这种极端形状对去皮和碾磨的影响，并研究其性状在与高产现代品种杂交时的表现。大麦中也有类似的突变。然而，对于可能控制这些突变或小麦或大麦籽粒发育的基因知之甚少；作为鉴定它们的第一步，我们将使用传统的遗传作图技术在小麦和大麦染色体上定位它们。这将使我们能够开发与它们相关的DNA标记，这可以被育种者用来在新品种中选择更好的颗粒形状。虽然来自不同植物物种的种子可能看起来非常不同，但许多科学家认为，产生它们的基本潜在发育过程是共享的；有人认为，在一个物种中发现的对发育有重大影响的基因可能在其他物种中有直接对应的基因。我们的目标是利用我们自己从模式物种拟南芥和玉米中获得的这些基因信息来识别那些可能与小麦或大麦有关的基因，以便我们利用这些基因来修改谷物的形状和大小，以达到我们的优势，并获得有关谷物发育过程如何发生的信息。

Milling is the process by which wheat is ground into flour, during which the wheat grain is separated into its different parts: the outer layers (bran), embryo (germ) and endosperm (white flour). Milling wheat or barley is particularly difficult because of the irregular shape of the grain: unlike rice which is more-or-less cylindrical, wheat and barley have a deep groove or crease on one surface; this makes separation of the endosperm from the outer layers problematical. Different wheat varieties yield different types of flour for bread or for biscuit making but the amount of flour extracted from each grain also differs. Work has shown that yield of flour per grain is dependent on grain size and also shape, as this determines the proportion of the grain that is taken up by the endosperm relative to other grain parts. Moreover, with the recent uptake of de-branning (removal of the outer layers) by flour mills, the importance of the shape and depth of the crease to flour extraction has become very significant. Breeders routinely select new varieties for improvements in grain yield, a component of which is grain size, but have not previously selected specifically for grain shape. This project aims to survey the range of different grain sizes and crease shapes that exist in varieties of wheat and to relate them to milling yield. Grain shape is also important for barley used for malting (sprouting) where short fat grains are desirable since this allows starch present in the endosperm to be more rapidly used as food for the sprouting embryo. One ancient sub-species of wheat that was grown in India and Pakistan has small spherical grains with a very shallow crease; part of our work will be to assess what effect this extreme shape has on de-branning and milling and to study how its characters behave when crossed into the high yielding modern varieties. Similar mutations are also known in barley. Little is known however, about the genes that may be controlling these mutations or the development of the wheat or barley grain; as a first step to identify them we will use conventional genetic mapping techniques to locate them on the wheat and barley chromosomes. This will enable us to develop DNA markers linked to them, which can be used by breeders to select for a better grain shape in new varieties. While seeds from different species of plants may look very different, many scientists believe that the basic underlying developmental processes that give rise to them are shared; it is suggested genes that are found in one species which are proved to have major effects on development could have a direct counterpart in other species. We aim to use our own information on such genes from the model species Arabidopsis and maize to identify those potentially involved in wheat or barley for our use to modify grain shape and size to our advantage as well as to obtain information on how the process of grain development occurs.