Genetic improvement of rice seed vigour for dry direct-seeded conditions

水稻是发展中国家最重要的粮食作物。据估计，亚洲有超过30亿人依靠大米提供30%到75%的卡路里。最广泛使用的水稻种植方法包括在苗圃发芽，然后将秧苗移栽到洪水泛滥的稻田。这种水坑移栽水稻(PTR)方法占全球水稻种植的约55%，占世界产量的约75%。然而，在南亚和东南亚的许多地区，农民正在转向直播水稻(DSR)，因为劳动力和水的可获得性正在下降，而与之相关的成本正在上升。西非也正在发生类似的转变。为了利用DSR获得好的作物，种子必须在土壤中迅速发芽，幼苗必须茁壮成长。然而，由于育种者一直专注于开发PTR品种，因此很少或根本没有对种子活力的选择。农学家强调了开发种子活力提高的水稻新品种的必要性，以便它们在干燥的直播条件下表现得更好。该项目的第一个目标是通过对1000个不同水稻品种进行基因组测序，并确定与种子活力相关的关键遗传差异，来确定哪些基因负责控制水稻种子活力。育种者可以利用这些知识来开发新品种。该项目的第二个目标是确定是否可以通过提高植物生长调节剂赤霉素在一种名为中胚轴的特定幼苗组织中的生产来改善现有的精英半矮秆水稻品种的地上部生长。当种子在更深的地方播种时，中胚轴伸长的增加可以帮助幼苗从土壤中长出。这是当前品种的一个关键弱点。

Rice is the most important staple crop in the developing world. It has been estimated that over three billion people in Asia rely on rice to provide 30 to 75% of their calories. The most widely used method for cultivating rice involves germinating the seeds in nurseries and transplanting the seedlings to flooded 'paddy' fields. This puddled transplanted rice (PTR) method accounts for ~55% of global rice cultivation and ~75% of world production. However, in many parts of South and Southeast Asia, farmers are switching to direct seeded rice (DSR) because the availability of labour and water is in decline and their associated costs are rising. A similar transition is also occurring in West Africa. To obtain a good crop using DSR it is imperative that the seeds germinate quickly in the soil and that the seedlings grow vigorously. However, because breeders have focused on developing varieties for PTR there has been little or no selection for seed vigour. Agronomists have highlighted a need for the development of new rice varieties with improved seed vigour so that they perform better in dry direct seeded conditions. The first aim of this project is to identify which genes are responsible for controlling seed vigour in rice by filming the germination of ~1000 different rice varieties that have had their genomes sequenced and identifying the key genetic differences that are associated with strong vigour. This knowledge can be used by breeder to develop new varieties. The second aim of this project is to determine whether the shoot growth of existing elite semi-dwarf rice varieties can be improved by enhancing the production of the plant growth regulator gibberellin in a specific seedling tissue called the mesocotyl. The increase in mesocotyl elongation could help seedlings to emerge from the soil when the seed has been planted at a greater depth. This is a key weakness of current varieties.