Unravelling the molecular genetic basis of Striga resistance in cereals: integrating Quantitative Trait Loci (QTL) and genomic approaches

水稻和高粱是撒哈拉以南非洲（SSA）和半干旱热带地区数百万人的两种主要主食，但作物生产和产量提高的主要制约因素是寄生杂草Striga。这种寄生虫附着在寄主植物的根部，导致严重的发育不良和谷物产量的损失。目前，Striga物种在撒哈拉以南非洲40%以上的谷物产区出没;它们对贫瘠土壤的影响最大，受影响最严重的是最贫穷的自给农民，杂草对他们的贫困和健康产生了重大影响。目前，减轻这种寄生虫影响的最常用策略包括人工除草，提高土壤肥力和使用“耐受”品种（即使感染也能生产一些谷物），但成功有限。虽然结合几种控制措施可能是必要的控制Striga，作物损失，由于寄生虫可以通过引入宿主抗性基因到最常用的品种显着减少。然而，由于缺乏抗性材料和对寄主对独脚金抗性的分子遗传性质缺乏了解，抗性品种的使用受到限制。在过去的5年里，我们在水稻中进行了广泛的筛选计划，并确定了对S.赫尔蒙席卡。水稻对独脚金抗性的发现具有重要意义，因为它是目前分子遗传学研究的最佳“模型”谷物，因为这种作物的基因组已经测序。在这个计划中，我们建议采取综合的方法来确定和调查的抗独脚金在水稻中的分子遗传性质，结合我们的广泛知识独脚金-主机的相互作用，我们的新的植物生长系统和现代基因组和比较基因组技术。然后，我们将利用从水稻中获得的信息来确定高粱中出现类似抗性的程度。该项目不仅将加强我们对抗独脚金分子遗传性质的基本理解，而且将有助于更有效的抗独脚金育种方法，可用于非洲水稻和高粱改良的区域和国家育种计划。改进稳定产量的品种并使自给农民采用这些品种，对于加强西非和撒哈拉以南非洲的长期粮食安全和减贫至关重要。

Rice and sorghum are two of the major staple foods for millions of people in sub Saharan Africa (SSA) and the semi-arid tropics yet a major constraint to crop production and yield improvement is the parasitic weed Striga. This parasite attaches to the roots of the host plant causing severe stunting and loss of grain yield. Currently Striga species infest over 40% of the cereal producing areas of SSA; their effects are greatest on infertile soils and those most severely affected are the poorest subsistence farmers upon whom the weed exerts major impacts on poverty and health. At present the most commonly used strategies for alleviating the impact of this parasite include hand weeding, improving soil fertility and the use of 'tolerant' cultivars (which produce some grain even when infected), however success has been limited. While combining several control measures is likely to be necessary for control of Striga, crop losses due to the parasite could be reduced significantly through introducing host resistance genes into the most commonly used cultivars. However, the use of resistant cultivars is limited by a lack of resistant material and by a lack of understanding of the molecular genetic nature of host resistance to Striga. Over the last 5 years we have carried out an extensive screening programme in rice and have identified cultivars that show good post-attachment resistance to S. hermonthica. The discovery of resistance in rice to Striga is of great significance as it is currently the best 'model' cereal for molecular genetic studies as the genome of this crop plant has been sequenced. In this programme we propose to take an integrative approach to identify and investigate the molecular genetic nature of resistance to Striga in rice by combining our extensive knowledge of Striga-host interactions, our novel plant growth systems and modern genomic and comparative genomic techniques. We will then use information gained from rice to determine the extent to which similar resistance occurs in sorghum. Not only will the project enhance our fundamental understanding of the molecular genetic nature of resistance to Striga but it will contribute to more efficient breeding methods for Striga resistance that could be used in regional and national breeding programmes in Africa for rice and sorghum improvement. The improvement of varieties which stabilize yields and their adoption by subsistence farmers is critical for enhanced food security and poverty reduction in West and sub Saharan Africa in the long term.