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，小麦和大麦在一个表面上有一个很深的沟槽或折痕，这使得胚乳与外层的分离成为问题。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，随着最近面粉厂采用去皮（去除外层），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，其中一个因素是粮食的大小，但以前没有专门选择粮食形状。本项目旨在调查小麦品种中存在的不同籽粒和折痕形状的范围，以了解不同形状是如何形成和发展的，以及它们与碾磨产量的关系。在印度和巴基斯坦种植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。我们的目标是利用来自模式物种拟南芥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我们的谷物形状，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 flourmills, 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, an element of which is grain size, but have not previously selected specifically for grain shape. This project aims to survey the range of different grain and crease shapes that exist in varieties of wheat to understand how the different shapes are formed and develop and how they relate to milling yield. One ancient sub-species of wheat that was grown in India and Pakistan has small spherical grains that have 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 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 information on such genes from the model species Arabidopsis to identify those potentially involved in wheat or barley for our use to modify grain shape to our advantage as well as to obtain information on how the process of grain development occurs.