Rhizo-Rice: a novel ideotype for deeper roots and improved drought tolerance

稻米是全球粮食安全的支柱。干旱压力是限制水稻产量的主要因素，由于全球气候变化的影响，预计未来情况将进一步恶化。因此，培育耐旱性更好的水稻品种是全球粮食安全的一个重要战略目标。该项目通过开发水稻品种来满足这一需求，这种新的水稻品种具有根系特征，使它们能够在干旱条件下改善土壤勘探和更有效地捕获水分。黑麦-水稻品系将具有1）更陡的根生长角度，2）更少的主根，3）在深层土壤中更大的根分枝，4）增加的根气隙（通气组织）的形成，这降低了根组织的成本，以及5）更小的导水导管（木质部），这迫使植物更节约地使用土壤水。据推测，这些特征的组合将比从其单独的影响中预测的更有价值。该项目将评估在田间和计算机模拟模型中的Ryngom-rice品系的效益，并将发现控制Ryngom-rice根系性状的遗传因素。此外，我们还将评估泰国水稻育种系中的这些根系性状，并培训泰国科学家将根系性状纳入水稻育种计划的方法。该项目整合了泰国领先的水稻研究人员和育种家、英国领先的作物生理学家和菲律宾国际水稻研究所的作物生理学家，以及英国领先的根系建模师。我们将通过测量在不同条件下生长的水稻植株的根系特征来研究不同的根构型和干旱条件如何影响水稻生长。通过记录不同类型根的数量、长度和角度，并拍摄根结构的显微图像，我们将测试这些特征如何影响耐旱性。这些测量将通过计算建模来补充，这将使我们能够测试许多不同的根系结构和干旱条件。我们以前已经开发了计算模型来模拟玉米，大麦，菜豆，羽扇豆和南瓜的根系生长。我们将调整这些模型来模拟水稻根系生长，这将使我们能够预测最佳的根系生长类型，以最大限度地提高干旱条件下的水分吸收。最后，我们将确定哪些基因负责创造理想的根结构。我们将使用最近开发的技术来分析许多不同品种的水稻的基因和根结构，这将使我们能够确定最大限度地提高耐旱性的合适品种。该项目将产生若干工具，以促进培育更耐旱的水稻品系。它将验证作为水稻育种选择目标的特定根系性状;将发现这些性状的遗传标记;将确定水稻种质中理想根系性状的来源，并将提高泰国科学家创建具有上级根系性状的水稻品系育种团队的能力。

Rice is a mainstay of global food security. Drought stress is a primary limitation to rice yields and is projected to worsen in the future due to the effects of global climate change. The development of rice cultivars with better drought tolerance is therefore an important strategic goal for global food security. This project addresses this need by developing Rhizo-rice, new rice lines that have root traits that permit them to have both improved soil exploration and more efficient water capture under drought conditions. Rhizo-rice lines will have 1) steeper root growth angles, 2) fewer major roots, 3) greater root branching in deep soil, 4) increased formation of root air spaces (aerenchyma), which reduces the cost of root tissue, and 5) smaller water conductance vessels (xylem), which forces the plant to use soil water more sparingly. It is hypothesized that these traits will have much more value in combination than would be predicted from their isolated effects. This project will evaluate the benefits of Rhizo-rice lines in the field and computer simulation modelling and will discover genetic elements controlling Rhizo-rice root traits. Furthermore, we will evaluate these root traits in rice breeding lines in use in Thailand and will train Thai scientists in methods to incorporate root traits in rice breeding programs.This project integrates leading rice researchers and breeders in Thailand, leading crop physiologists in the UK and at the International Rice Research Institute in the Philippines, and leading root modelers in the UK. We will investigate how different root architectures and drought conditions affect rice growth by measuring features of the root system in rice plants grown in different conditions. By recording the number, length and angle of different types of roots and taking microscopy images of the root structures, we will test how these features affect drought tolerance. These measurements will be complemented by computational modelling, which will enable us to test many different root structures and drought conditions. We have previously developed computational models to simulate root growth in maize, barley, common bean, lupin and squash. We will adapt these models to simulate rice root growth, which will enable us to predict the best type of root growth to maximise water uptake in drought conditions. Finally, we will determine which genes are responsible for creating the desirable root structures. We will use recently developed techniques to analyse the genes and root structures in many different varieties of rice, which will enable us to identify suitable varieties for maximising drought tolerance. This project will generate several tools to facilitate the breeding of more drought tolerant rice lines. It will validate specific root traits as selection targets in rice breeding; will discover genetic markers for these traits; will identify sources for desirable root traits in rice germplasm, and will enhance the ability of Thai scientists to create a team for breeding rice lines with superior root traits.