Molecular plant pathogenesis: regulation and impacts of bacterial soft rot virulence factors

布景主题：农业和粮食安全由于农业和粮食安全的影响，以及战略政策，BBSRC认为植物病理学是一个“脆弱”的研究领域，需要积极的DTP投资技能培训，非常适合剑桥DTP支持。软腐欧文氏菌属（现在的果胶杆菌属和狄氏菌属）侵袭马铃薯作物和各种蔬菜作物。这些病原菌都是对农业和科研影响最大的植物病原菌之一。项目名称：共同主管，乔治萨尔蒙德（生物化学）和约翰卡尔（植物科学），成功地合作了一个项目，涉及植物病原体，果胶杆菌（最初欧文氏菌）。跨部门合作发现了一种新的细菌毒素，在卡尔实验室进行的拟南芥试验中，这种毒素是坏死和致命的。细菌毒素（Nip;坏死诱导蛋白）的产生受群体感应（QS）控制，即受可扩散的细胞间化学信号N-3-氧代己酰基高丝氨酸内酯调节。在植物群体感应调节子中，Nip的产生是多个毒力决定因子之一，在植物病害中起着关键作用。其他QS调节子成员包括植物细胞壁降解酶（PCWDE：果胶酶、纤维素酶和蛋白酶）和共调节蛋白质分泌机器（特别是I型和II型）。该项目将使用病原体（果胶杆菌，如果时间允许，还将使用立枯迪克氏菌）的转录报告基因融合（LacZ、UidA、Gfp）菌株，以调查对Nip和PCWDE生产的监管投入。除了QS，我们还将评估毒素加工的新环境和生理输入。一些毒力因子受温度调节，其同源基因也可响应渗透压、pH和C、N和P营养有效性。这将通过使用适当的病原体报告基因融合菌株的高通量筛选进行评估。重要的是，我们打算研究植物信号在病原体基因诱导中的影响，最初使用植物提取物（茄属和拟南芥属）在筛选试验中定义植物诱导基因（通过高密度基因融合阵列）。将在植物中测试植物诱导基因突变体的毒力影响，并进一步检查那些表现出植物病理学影响（和/或对特定环境或生理线索的反应）的突变体。它们将与野生型一起用于蛋白质组学分析和RNA-seq研究，以确定新型调节剂在植物攻击中的更广泛的转录和蛋白质组学影响。这个项目将是数据丰富，具有可塑性的突发事件，所以是一个博士项目的理想选择。博士生将受益于跨两个部门的跨学科共同监督。她将获得植物病理学的战略重要领域的核心技能，以及遗传学，生物信息学和一些组学技术（蛋白质组学和RNA-seq）的基础技能。鉴于英国的植物病理学技能差距（正如BBSRC所强调的那样），毕业生将在基础研究或转化农业产业中具有很高的就业能力。

Theme: Agriculture and Food SecurityBecause of agriculture and food security ramifications, and strategic policy, BBSRC consider plant pathology as a "vulnerable" research area requiring active DTP investment in skills training, highly appropriate for Cambridge DTP support. Soft rotting Erwinia species (now Pectobacterium and Dickeya species) attack potato crops and various vegetable crops. These pathogens are in the "top ten" of plant pathogenic bacteria for agricultural and research impact. Project: The co-supervisors, George Salmond (Biochemistry) and John Carr (Plant Sciences), collaborated successfully on a project involving the plant pathogen, Pectobacterium (originally Erwinia). The interdepartmental collaboration uncovered a novel bacterial toxin that was necrotic and lethal in Arabidopsis assays done in the Carr laboratory. Production of the bacterial toxin (Nip; necrosis inducing protein) is under quorum sensing (QS) control i.e regulated by a diffusible intercellular chemical signal, N-3-oxohexanoyl homoserine lactone. Nip production is one of multiple virulence determinants in the quorum sensing regulon that plays key roles in plant disease. Other QS regulon members include plant cell wall degrading enzymes (PCWDEs: pectinases, cellulases and proteases) and co-regulated protein secretion machines (Type I and Type II in particular). This project will use transcriptional reporter gene fusion (LacZ, UidA, Gfp) strains of the pathogen (Pectobacterium and, if time allows, Dickeya solani) to investigate regulatory inputs to Nip and PCWDE production. In addition to QS, we will assess new environmental and physiological inputs to toxin elaboration. Some virulence factors are thermoregulated and their cognate genes could also respond to osmolarity, pH and C, N and P nutritional availability. This will be assessed by high throughput screening using appropriate pathogen reporter fusion strains. Importantly, we intend to investigate the impacts of plant signals in pathogen gene induction, initially using plant extracts (Solanum and Arabidopsis) in screening assays to define plant-inducible genes (via high density gene fusion arrays). Plant-inducible gene mutants will be tested in planta for virulence impacts and those exhibiting plant pathology impacts (and/or response to specific environmental or physiological cues) will be examined further. They will be used, with wild type, for proteomic analyses and RNA-seq studies to define wider transcriptional and proteomic impacts of the novel regulators in plant attack. This project will be data-rich, with malleable contingencies and so is ideal for a PhD project. The PhD student will benefit from interdisciplinary co-supervision across two departments. She will acquire core skills in the strategically important area of plant pathology plus underpinning skills in genetics, bioinformatics, and some 'omics technologies (proteomics and RNA-seq). Given the phytopathology skills gap in the UK (as highlighted by the BBSRC) the graduate will be highly employable, in basic research or translational agricultural industries.