Enhancing wheat field performance and response to abiotic stress with novel growth-regulatory alleles

从20世纪60年代开始，提高全球谷物产量的“绿色革命”是由于小麦和水稻新品种的结合以及氮肥和农药使用的增加。新品种的一个重要特征是高度降低。虽然最初引入这些植物是为了让它们能够耐受高水平的肥料，而不会过度生长和枯萎，但人们发现，这些新的半矮秆品种提高了产量，因为植物在生产秸秆上浪费的能量更少，而更多的能量被用于收获的谷物。我们现在知道，这些矮种小麦携带了一种基因（称为“矮高”或Rht），使它们对植物自身的生长激素赤霉素（GA）没有反应，而赤霉素通常会增加茎秆的高度。同样，新的半矮秆水稻品种含有一种缺陷基因，导致激素水平降低。只有两种类型的Rht基因被广泛用于小麦，其中一种主要用于英国品种。气候变化、农业实践和可能限制使用生长调节化学品可能意味着含有这种基因的小麦品种不再能够产生最高产量。该项目的一部分目的是鉴定改变遗传信号从而对身高产生不同影响的小麦新基因。然后，这些基因可以单独或与现有的Rht基因结合，用于生产新的矮秆品种。我们还发现，矮化基因，通过遗传信号的变化使植物降低高度，也保护植物免受干旱、高温或盐的胁迫。随着气候变化减少了小麦产区的降雨量，这一点可能变得更加重要。有证据表明，现有的Rht基因并不是保护小麦植株免受胁迫的理想基因。因此，该项目的第二个目标将是测试受遗传信号影响的一系列基因，以了解它们在保护植物免受干旱和其他胁迫方面的有效性。最后，该项目的一个重要目标是，我们发现的新的矮化基因应该被植物育种家采用，以开发新的商业品种。因此，我们与国家农业植物学研究所一起制定了一项“预育种”战略，将这些新基因引入现代高产品种，这些品种可以传递给育种者并用于他们的小麦育种计划。

The 'Green Revolution' that improved worldwide cereal yields from the 1960s was due to a combination of new varieties of wheat and rice and the increased use of nitrogen fertilisers and pesticides. An important feature of the new varieties was reduced height. Although originally introduced to allow the plants to tolerate high levels of fertiliser without overgrowing and collapsing, it was discovered that these new semi-dwarf varieties increased yield, as less of the plants' energy was wasted on producing straw and more went into the harvested grain. We now know that these dwarf varieties of wheat carried a gene (called 'Reduced Height' or Rht) that made them unresponsive to the plant's own growth hormone, gibberellin (GA), which normally increases stem height. Similarly, the new semi-dwarf rice varieties contained a defective gene that resulted in reduced levels of the hormone. There are only two types of Rht gene that have been widely used in wheat, and predominantly one in UK varieties. Changes in climate, agricultural practise and possible restrictions in the use of growth-regulating chemicals may mean that wheat varieties containing this gene are no longer capable of producing the highest yield. Part of this programme is aimed at identifying new wheat genes that alter GA signalling and therefore have different effects on height. These genes could then be used to produce new dwarf varieties, either alone or in combination with the existing Rht genes. We have also discovered that dwarfing genes, that confer reduced height through changes in GA signalling, also protect plants against stresses such as drought, heat, or salt. This may become even more important as climate change reduces the amount of rainfall in wheat-producing areas. There is evidence that the existing Rht gene is not ideal for protecting wheat plants from stress. A second aim of this project will therefore be to test a range of genes affected in GA signalling for their effectiveness in protecting plants from drought and other stresses. Finally, an important aim of this project is that the new dwarfing genes that we discover should be taken up by plant breeders to develop new commercial varieties. Therefore, we have developed a 'pre-breeding' strategy with the National Institute of Agricultural Botany to bring these new genes into modern, high-yielding varieties that can be passed on to breeders and used in their wheat breeding programmes.