Exploiting the immune system to tackle emerging filamentous diseases in tomato

未来40年，世界人口预计将增加16亿，这对人类提出了将粮食产量增加70%的挑战。尽管目前采取了控制措施，但在使用有效控制措施后，杂草、害虫和病原体仍占我们主要作物产量的40%。丝状真菌病原体（例如霉菌、霉菌和晚疫病）的控制特别困难，因为它们的进化能力使它们非常擅长克服基因或化学杀虫剂提供的抗性。在过去的世纪里，出现了越来越多的致病真菌。由于粮食流动和气候变化，农业系统极易受到丝状疾病的出现和流行的影响。此外，在受控环境下的作物栽培，即使它在增加产量方面提供了优势，但它在控制丝状疾病的传播方面表现出明显的劣势。目前的控制方法主要依赖于使用杀真菌剂，由于其对人类健康和环境的毒性，这些杀真菌剂受到严格的欧洲监管。因此，迫切需要开发控制疾病的替代策略。植物通过组成型和诱导型防御策略来防御有害微生物。或者，植物已经进化出了使其免疫系统对攻击者做出更快、更强反应的能力。这种所谓的防御启动可以由警告即将到来的攻击的各种信号触发，包括使用引发剂如b-氨基丁酸（BABA）的治疗。BABA已被证明提供针对广泛的丝状疾病的保护。这种出色表现的原因是由于其在不同防御信号通路上的启动活性，这些信号通路被植物用于对抗不同生活方式的疾病。BABA已被证明可有效诱导作物如番茄对广谱疾病的抗性。丝状菌病原体在这种作物中特别成问题，因为它们是收获前后产量损失的原因。番茄是茄科研究的模式植物，其基因组已被测序，与其野生亲缘植物的杂交使研究不同过程背后的遗传学成为可能。然而，只有一项研究在拟南芥中研究了诱导抗性反应的遗传变异。该项目将研究BABA在番茄中诱导抗性触发的遗传变异，其总体目标是确定可能最大限度地提高商业品种诱导抗性能力的有利性状。为了实现这一目标，我将测试ABA诱导的抗性对毁灭性的病原体致病疫霉（晚疫病）在重组自交系（RIL）人口之间的商业番茄品种，并加入野生相对的交叉。诱导抗性定量将通过使用复杂的表型扫描仪进行，该扫描仪可以以高通量方式成像和分析不同的疾病参数。诱导的抗性性状（IR性状）将通过显着的数量性状基因座（QTL）的测序和响应背后的分子机制进行了研究。该项目的最后一部分将测试以下假设：由于IR性状而产生的多向抗性提供了有效的保护，以对抗新发现的具有高出现风险的丝状病原体菌株，例如晚疫病或枯萎病菌株（由多宿主病原体尖孢镰刀菌引起）。这项工作的结果将确定遗传性状，以利用番茄免疫系统增强对广谱疾病的防御，包括可能具有巨大破坏潜力的新兴病原体。

The world's population is expected to increase by 1.6 billion in the next 40 years, which challenges humanity to increase food production by 70%. Despite current control measures, weeds, pests and pathogens claim up to 40% of our major crop yields after use of effective control. Filamentous pathogens (e.g. mildews, molds and late blight) are exceptionally problematic to control as their evolutionary capacity makes them highly proficient on overcoming the resistance offered by genes or chemical pesticides. In the past century, there has been an increasing number of virulent emerging pathogenic fungi. Agricultural systems are extremely vulnerable to emergence and epidemics of filamentous disease due to food mobility and climate change. Moreover, crop cultivation under controlled environment, even when it provides advantages in terms of increased production, it represents a clear disadvantage in controlling the spread of filamentous diseases. Current methods of control depend largely on the use of fungicides, which are under strict European regulation due to its toxicity to human health and the environment. Therefore, it is urgent to develop alternative strategies to control diseases. Plants are equipped to defend themselves against harmful microbes through constitutive and inducible defence strategies. Alternatively, plants have evolved the capacity to prepare their immune system to respond faster and stronger against attackers. This so-called priming of defence can be triggered by a variety of signals that warn of an upcoming attack, including treatments with priming agents such as b-amino butyric acid (BABA). BABA has been shown to provide protection against a wide spectrum of filamentous diseases. The reason for this outstanding performance is due to its priming activity at different defence signalling pathways that are used by plants to fight diseases with different lifestyles. BABA has been shown to be effective in inducing resistance against a broad-spectrum of diseases in crops such as tomato. Filamentous pathogens are particularly problematic in this crop as they are responsible for yield loses pre- and post-harvest. Therefore, emerging filamentous diseases are a serious threat to the tomato market.Tomato is a model plant for research in Solanaceae as its genome has been sequenced and crosses with their wild relatives allow the study of the genetics behind different processes. However, only one study in Arabidopsis has investigated genetic variation in the induced resistance response. This project will investigate genetic variation in induced resistance trigger by BABA in tomato with the overarching aim to identify advantageous traits which could potentially maximise the inducible resistance capacity of commercial varieties. To achieve this aim, I will test BABA-induced resistance against the devastating pathogen Phytophthora infestans (late blight) in a Recombinant Inbred Line (RIL) population from the cross between a commercial tomato cultivar, and an accession of the wild relative. Induced resistance quantification will be done by using a sophisticated phenotyping scanner that can image and analyse different disease parameters in a high-throughput manner. The induced resistance traits (IR-traits) will be identified by sequencing of the significant quantitative trait loci (QTLs) and the molecular mechanisms behind the response will be investigated. The last part of the project will test the hypothesis that multi-directional resistance as a result of the IR-traits offers effective protection against newly identified strains of filamentous pathogens with a high risk of emergence, such as strains of late blight or Fusarium wilt (caused by the multi-host pathogen Fusarium oxysporum). The results coming from this work will identify the genetic traits to exploit the tomato immune system for enhanced defence against a broad-spectrum of diseases, including emerging pathogens that can have a huge devastation potential.