Characterising broad-acting resistance to bacterial canker of cherry and elucidating tissue-specific mechanisms of immunity

细菌性溃疡病是樱桃上的一种主要病害，由樱桃假单胞菌引起，在整个季节中占据不同的组织。抗性育种可以在限制这种疾病方面发挥重要作用。我们的研究表明，一些樱桃品种对所有病原体都表现出广泛的部分抗性。这种抗性可能是数量上的，涉及一系列性状。与此相反，野生樱桃种质表现出很强的抗性，可能是简单的遗传，涉及一个或几个主基因。 这个博士项目将侧重于通过对在东马岭繁殖的野生和甜樱桃种群进行基因分型和表型分析来表征抗性的遗传基础，目的是确定新的溃疡病抗性来源。这将导致用于育种的分子标记的发展。此外，学生将开始研究不同宿主组织中抗性反应的生物学基础。 正在进行的细菌溃疡病研究表明，不同组织的易感性不同。田间抗性在叶和果实试验中不能完全复制。学生将优化分析，以了解免疫反应，例如活性氧的测量和研究免疫基因表达。他们将使用荧光标记菌株的显微镜来跟踪感染和细菌突变体，以剖析发生的免疫反应。

Bacterial canker is a major disease of cherry caused by various Pseudomonas syringae pathogens that occupy different tissues throughout the season. Resistance breeding could play a large role in limiting this disease. Our research has shown that broad-acting partial resistance towards all pathogens is exhibited by some cherry cultivars. This resistance is likely to be quantitative, involving a range of traits. In contrast, wild cherry accessions exhibit strong resistance that may be simply inherited and involve one or a few major genes. This PhD project will focus on characterising the genetic basis of resistance by genotyping and phenotyping wild and sweet cherry populations propagated at East Malling, with the aim to identify novel sources of resistance to canker. This would lead to the development of molecular markers for use in breeding. In addition, the student will begin to study the biological basis of resistance responses in different host tissues. Ongoing work on bacterial canker has shown that different tissues vary in their susceptibility. Field resistance is not replicated fully in leaf and fruit tests. The student will optimise assays to understand immune responses e.g. measurement of reactive oxygen species and study immune gene expression. They will use microscopy of fluorescently tagged strains to follow infection and bacterial mutants to dissect the immune responses occurring.