Horticulture: Seeking new tools to manipulate soil and root microbiology for biocontrol of soft fruit Phytophthora diseases

全球数据估计，每年高达40%的作物产量因病虫害而损失。树莓疫霉根腐病是由土传病原菌疫霉鲁比引起的。当鲁比的游动游动孢子被吸引到生长的根尖时，初始感染开始，游动孢子感染并通过整个根系传播，破坏组织并阻止营养和水的吸收，杀死植物。每次感染都会释放游动孢子，然后传播到其他植物。鲁比疫霉可能已经存在于种植地点，因为孢子可能持续多年，对极端环境和许多杀虫剂具有抗性。另外，新的感染可以到达受感染的植物，或通过灌溉水通过受污染的土壤。最初的游动孢子阶段依赖于自由土壤水分。英国软果产业受到根腐病的破坏，迫使种植者在基质中使用基于盆栽的系统生产80%的英国树莓，以避免接触受污染的田间土壤。然而，根腐病仍然是一个巨大的问题，因为引起该疾病的疫霉病原体存在于繁殖种群中，并且可以在灌溉水中局部传播。为了保护树莓产业，必须确定新的、更可持续的持久有效的病原体控制方法。事实上，要实现英国政府的净零排放战略，就需要提高可持续性、复原力和资源利用效率，该战略打算在十年左右的时间内将英国的净排放量减半，并在2050年前实现零排放。新的可持续基质的潜力，更有效地管理水与新的IPM工具相结合，以控制疾病是这一战略的一部分，目前正在开发中，有很大的潜力，为这些管理根疾病抑制栽培措施，如使用有机覆盖物，包括木屑，堆肥或树皮可以帮助抑制土壤病原体种群。在一些有机覆盖物中发现的微生物活性已被证明会导致疫霉菌丝细胞壁的破裂。木霉是一种重要的自由生活的真菌属，包括许多菌株，可以直接与根相互作用，促进植物生长，提高抗病性，并增加对非生物胁迫的耐受性。已知许多木霉属菌株具有针对真菌病原体的直接拮抗活性，并且具有通过一系列机制如资源竞争、寄生、真菌寄生、菌丝相互作用和分泌酶来减少由病原体引起的疾病症状的潜力。在这里，我们将调查这些潜在的好处，树莓作为一个模式木本物种，有可能帮助控制过多的其他经济和环境显着的疫霉属疾病。我们已经建立了一个免费的团队来筛选几种木霉真菌物种，以确定它们是否适合作为一系列树莓品种的土壤和基质添加剂。他们对卵菌菌落生长的直接影响将被执行和盆为基础的研究将提供一个评估的健康和恢复力的木本模式主机树莓在木霉的存在下，在可持续的基板上发展的疾病引起的致病Phytophthora.Non-chemical方法抑制疫霉根腐病的目标病原体的生命周期的不同阶段。已经开发了新的基质，其限制了自由水的可用性，从而降低了游动孢子传播的能力，防止了新的感染。疫霉根腐病的生物防治涉及添加对疫霉属具有拮抗性的生物体，或者间接地通过竞争营养物质、产生抑制性化合物，或者直接地通过寄生作用。联合有效的控制是可能的。

Worldwide figures estimate that up to 40% of crop yields are lost to pest and diseases each year. Phytophthora root rot of Raspberry is caused by the soilborne pathogen Phytophthora rubi. Primary infection is initiated when motile water-borne zoospores of P. rubi are attracted to growing root tips, which they infect and spread through the whole root system destroying tissue and preventing nutrient and water uptake, killing the plant. Each infection releases zoospores which then spread to other plants. Phytophthora rubi may already be present on planting sites, as spores may persist for many years, being resistant to environmental extremes and many pesticides. Alternatively new infections can arrive on infected plants, or via irrigation water which has passed through contaminated soil. The initial motile spreading phase (zoospores) are reliant on free soil water. The UK soft fruit industry has been devastated by root rot disease that forced growers to produce 80% of UK raspberries using pot-based systems in substrate to avoid contact with contaminated field soil. However, root rot is still a huge problem as the Phytophthora pathogen responsible for the disease is present in propagation stocks and can spread locally in irrigation water. To protect the raspberry industry, it is imperative that new, more sustainable methods of durable and effective pathogen control are identified. Indeed, improvements in sustainability, resilience and resource-use efficiency are required to meet the UK Government's Net Zero Strategy, that intends to halve UK net emissions in around a decade and eliminate them by 2050. The potential for new sustainable substrates that manage water more efficiently in combination with novel IPM tools to control disease are part of this strategy and are currently under development and there is great potential for these to manage root diseasesDisease suppressive cultural practices such as the use of organic mulches including sawdust, compost or bark can help to suppress soil pathogen populations. The microbial activity found in some organic mulches have been shown to cause breakdown of cell walls of Phytophthora hyphae. Trichoderma is an important free-living fungal genus comprising many strains that can interact directly with roots, promote plant growth, boost resistance to diseases, and increase tolerance to abiotic stresses. Many Trichoderma strains are known for their direct antagonistic activity against fungal pathogens and potential to reduce disease symptoms caused by pathogens by a range of mechanisms such as competition for resources, antibiosis, mycoparasitism, hyphal interactions, and secreted enzymes. Here we will investigate these potential benefits to raspberry as a model woody species with potential to help control a plethora of other economically and environmentally significant Phytophthora diseases. We have established a complimentary team to screen several Trichoderma fungal species for their suitability as an additive to soil and substrates in a range of Raspberry cultivars. Their direct impact on oomycete colony growth will be performed and a pot-based study will provide an assessment of health and resilience of the woody model host raspberry in presence of Trichoderma in sustainable substrate on the development of disease caused by pathogenic Phytophthora.Non-chemical approaches for suppression of Phytophthora root rots target different phases of the life cycle of the pathogen. New substrates have been developed which limited the availability of free-water and hence reduce the ability of the motile zoospores to spread preventing new infections. Biocontrol of Phytophthora root rot involves the addition of organisms which are antagonistic to Phytophthora, either indirectly via competition for nutrients, production of suppressive compounds, or directly via parasitism. Combined effective control may be possible.