Pseudomonas biocontrol of kiwifruit canker: elucidating novel mechanisms of bioactivity

猕猴桃溃烂病(PSA)是一种严重威胁全球猕猴桃产业的细菌病害。虽然目前存在PSA的治疗方法，但这些化学方法可能会造成环境破坏，并面临耐药PSA病毒型的风险。因此，迫切需要对PSA进行有效、可持续的治疗。我们在JIC的实验室是国际公认的微生物学和植物科学的卓越中心，在我们与主要猕猴桃种植者Zespri的实验室之前的一次成功合作中，我们鉴定出了几种天然存在的生物活性细菌菌株，它们能够强烈抑制温室种植的猕猴桃中的PSA感染。随后的工作是确定每个菌株的生物活性机制，发现了多个以前未表现出特征的生物合成基因簇(BGC)，这些基因簇的破坏取消了实验室中的PSA抑制。这个博士项目将对具有生物活性的BGC及其产生的天然产物进行深入的表征，以解决我们的生物活性细菌的作用模式。学生将使用天然产物生物化学和生物测定引导的分馏来分离和表征每种生物活性BGC的天然产物。他们将结合遗传学和靶向代谢组学检查其生物合成来源，并将进行生物控制分析，以确定其天然产品在植物中的重要性。该项目将支持新西兰正在进行的田间试验和生物活性注册工作，并确定几种新天然产品的结构-活性关系，这是他们未来商业发展的关键一步。学生将接受高级分子生物学和细菌遗传操作方面的培训，以及尖端有机化学技术，包括基于LC-MS的代谢组学、生物测定指导的分离和使用2D核磁共振进行结构阐明。他们还将接受植物感染和生物防治分析方面的广泛培训，以及适用于许多就业领域的面向行业的可转移软技能。这个与行业相关的项目将包括与我们在新西兰的商业合作伙伴Zespri一起工作的3个月的安置。

The bacterial disease kiwifruit canker (Psa) is a significant threat to the global kiwifruit industry. While treatments for Psa currently exist, these chemical approaches can cause environmental damage and are at risk from resistant Psa pathovars. There is consequently an urgent need for effective, sustainable treatments for Psa. During a successful previous collaboration between our labs at JIC; an internationally recognised centre of excellence for microbiology and plant science, and the major kiwifruit grower Zespri, we identified several naturally occurring, bioactive bacterial strains that strongly suppress Psa infections in greenhouse-grown kiwifruit. Subsequent work to identify the mechanism of bioactivity in each strain identified multiple previously uncharacterised biosynthetic gene clusters (BGCs), whose disruption abolishes Psa suppression in the lab.This PhD project will undertake the in-depth characterisation of the bioactive BGCs and their resulting natural products to address the mode of action of our bioactive bacteria. The student will use natural-product biochemistry and bioassay-guided fractionation to isolate and structurally characterise the natural products of each bioactive BGC. They will examine their biosynthetic origin using a combination of genetics and targeted metabolomics, and will conduct biocontrol assays to determine the importance of their natural products in planta.This project will support the ongoing field trial and bioactives registration work in New Zealand and define the structure-activity relationship of several new natural products, which is an essential step in their future commercial development. The student will receive training in advanced molecular biology and bacterial genetic manipulation, alongside cutting-edge organic chemistry techniques including LC-MS-based metabolomics, bioassay-guided fractionation and structural elucidation using 2D NMR. They will also receive extensive training in plant infection and biocontrol assays, alongside industry-facing, transferable soft-skills with applicability to many employment areas. This industry-linked project will include a 3 month placement working alongside our commercial partners, Zespri, in New Zealand.