A strategy for broad root disease resistance in barley

提高作物产量以养活世界是我们这个世纪的一项重大挑战，但它受到丝状植物病原体引起的疾病的阻碍。一个特别的挑战是由根部病原体引起的疾病，因为几种具有相似感染策略的不同真菌可能会导致根腐病。病原菌和植物之间的军备竞赛要求不断调整作物种质，以应对新出现的具有新毒力特征的病原菌小种。但对根腐病病原菌的特定抗性基因尚不清楚。此外，利用转基因方法部署抗性基因也遭到了公众的强烈反对。一种可行的替代方案是基于对感染关键寄主过程的操纵来定量抗病，因为它具有更高的持久性，并可能影响多种不同的根部病原菌。这项提议的创新方面是探索一种新发现的机制，这种机制是单子叶和双子叶植物在不影响生长、发育和种子产量性状以及植物与共生真菌相互作用的情况下普遍需要的。大麦是全球第四大种植谷物，对英国经济至关重要。它也是一个很好的实验模型，具有完全测序的二倍体基因组和关于其地上部抗病和根微生物区系的广泛信息。我们的工作揭示了编码保守的SCAR/WAVE复合体蛋白质组分的SCAR基因的失活，该复合体参与了根尖的局部细胞运输，可以改变细胞壁，使大麦的根对丝状病原体产生抗性，同时对生长、发育和种子产量没有不利影响。基于这一知识和资源，我们现在可以解决SCAR突变体介导的大麦根部抗性是否延伸到英国相关的丝状根腐病病原体(卵菌和真菌)。我们已经创造了所需的大麦种质，但需要资金支持，以进行感染过程的彻底特征，以及在理想和压力条件下与英国相关的病原体的感染研究。重要的是，我们还想检查这种种质形成根相关微生物区系的能力，并测试它与真菌共生的能力。在拟议的实验完成后，我们将很好地了解以前未探索的大麦SCAR蛋白是否控制丝状病原体的定植过程。我们将知道单个疤痕基因是否影响根部感染，以及它们是否是真菌共生所必需的。我们还将获得有关去除SCAR蛋白的影响以及植物与其土壤环境相互作用的重要信息。这将使我们能够推荐一个特定的SCAR基因作为非转基因突变育种的有希望的目标，以实现对谷物中丝状病原体的广泛抗逆性，并招募工业合作伙伴在具有经济意义的大麦品种中开发与欧盟市场兼容的最终种质。

Increasing crop yield to feed the world is a major challenge of our century but it is hampered by diseases caused by filamentous plant pathogens. A particular challenge are diseases caused by root pathogens because several different fungi with similar infection strategies can lead to root rots. The arms race between pathogen and plant demands constant adjustment of crop germplasm to tackle emerging pathogen races with new virulence features. But specific resistance genes against root rotting pathogens are not known. In addition, resistance gene deployment by use of transgenic approaches has encountered significant opposition from the public. A viable alternative is quantitative disease resistance based on manipulation of infection-critical host processes since it has a higher probability for durability and potentially may affect multiple different root pathogens. The innovative aspect of this proposal is to explore a newly discovered mechanism that is universally required for root access in monocot and dicot plants without impacting growth, development and seed yield traits as well as plant interactions with symbiotic fungi.Barley is the fourth most cereal cultivated globally and pivotal to the UK economy. It is also an excellent experimental model with a fully sequenced diploid genome and extensive information on its shoot disease resistance and root microbiota. Our work has revealed that inactivation of a SCAR gene encoding a protein component of the conserved SCAR/WAVE complex involved in localised cell trafficking at root tips can alter cell walls and renders roots of barley resistant to a filamentous pathogen while having no detrimental impact on growth, development and seed yield.Building on this knowledge and resource we can now address whether scar-mutant mediated barley root resistance extends towards Uk relevant filamentous root rot pathogens (oomycetes and fungi). We have already generated the required barley germplasm but require funding support to carry out a thorough characterisation of the infection process as well as infection studies with UK-relevant pathogens under ideal and stressed conditions. Importantly, we also want to examine the capacity of this germplasm to shape root associated microbiota and test its competence for fungal symbiosis.Upon completion of the proposed experiments we will have a good understanding whether previously unexplored barley SCAR proteins control filamentous pathogen colonisation processes. We will know whether individual SCAR genes impact on root infections and whether they are required for fungal symbiosis. We will also have obtained important information on the impact of SCAR protein removal and on the plant's interaction with its soil environment. This will allow us to recommend a specific SCAR gene as promising target for non-transgenic mutagenesis breeding to achieve broad resilience against filamentous pathogens in cereals and to recruit industrial partners to develop a EU market-compatible final germplasm in barley varieties of economic relevance.