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

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投资于技能培训，非常适合剑桥DTP的支持。软腐烂的欧文氏菌(现在的腐烂欧文氏杆菌属和迪克亚属)侵袭马铃薯作物和各种蔬菜作物。这些病原菌都在“十大”植物病原菌中，对农业和科研都有影响。项目：共同主管乔治·萨尔蒙德(生物化学)和约翰·卡尔(植物科学)成功地合作了一个涉及植物病原细菌(最初是Erwinia)的项目。部门间的合作发现了一种新的细菌毒素，这种毒素在CARR实验室进行的拟南芥测试中是坏死和致命的。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-氧代己酰高丝氨酸内酯的调控。NIP的产生是在植物病害中起关键作用的群体感应调节子中的多种毒力决定因素之一。其他QS调节子成员包括植物细胞壁降解酶(PCWDEs：果胶酶、纤维素酶和蛋白酶)和共同调节的蛋白质分泌机(特别是I型和II型)。该项目将使用病原体(Pecto杆菌，如果时间允许，还可以使用Dikeya solani)的转录报告基因融合(LacZ、UidA、GFP)菌株来调查NiP和PCWDE生产的调控输入。除了QS，我们还将评估新的环境和生理输入，以进行毒素精制。一些毒力因子受温度调节，它们的同源基因也可以对渗透压、pH和C、N、P营养供应做出反应。这将通过使用适当的病原体报告融合菌株的高通量筛选来进行评估。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(茄子和拟南芥)进行筛选，以确定植物诱导基因(通过高密度基因融合阵列)。植物诱导基因突变体将在植物中进行毒性影响测试，那些表现出植物病理影响(和/或对特定环境或生理线索的反应)的基因突变将被进一步检查。它们将与野生型一起用于蛋白质组分析和RNA-SEQ研究，以确定新调节剂在植物攻击中更广泛的转录和蛋白质组学影响。这个项目将是数据丰富的，具有可塑性的意外情况，因此是一个理想的博士项目。这位博士生将受益于两个系之间的跨学科合作监督。她将获得具有战略重要性的植物病理学领域的核心技能，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缺口(如BBSRC所强调的)，毕业生将在基础研究或转基因农业行业获得高度就业机会。

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.