Identification, cloning and functional characterization of genes related to fire blight resistance in Malus X robusta

由淀粉欧文氏菌引起的火疫病目前是包括德国和瑞士在内的几个欧洲国家苹果生产的主要限制因素。只有使用抗生素才能有效控制，但应用受到特别限制，并不受欢迎。一个对环境无害的选择是种植抗病苹果品种，但现有的抗病品种不能满足消费者的需求。由于抗病新品种的选育非常耗时，而且没有人能保证苹果会被消费者接受，利用重组DNA技术改良已被接受的品种是利用苹果自有基因解决火疫病的最有前途的策略。因此，基于图谱的克隆方法将被用来分离QTL区域，解释最近在野生物种M.X robusta 5(Mr 5)中检测到的高达80%的表型变异。获得的序列将用于鉴定候选基因(S)，然后对其进行分子鉴定，并在转基因植物中进行测试。最有希望的候选基因(S)最终将被用来培育苹果抗火疫病顺性植株。此外，还将对野生型和突变型病原菌接种后Mr 5差异表达的下游作用基因和蛋白的鉴定和特性进行分析，以进一步了解其抗火疫病的机制。

The fire blight disease caused by the bacterium Erwinia amylovora is currently the major constraint for apple production in several European countries including Germany and Switzerland. An effective control is only possible with antibiotics but the application is particular restricted and not desired. An environmentally sound alternative is the growing of resistant apple cultivars, but available resistant cultivars do not fit the consumer demands. Since the breeding of a new resistant cultivar is very time consuming and nobody can assure that the apple will be accepted by the consumers the use of recombinant DNA-technology for the improvement of accepted cultivars offers the most promising strategy to solve the problem of fire blight by using Malus own genes. Therefore a map based cloning approach will be used to isolate a QTL region, explaining up to 80% of the phenotypic variance, recently detected in the wild species M. X robusta 5 (Mr5). The obtained sequence will be used to identify candidate gene(s), which will then be molecular characterized and tested in transgenic plants. The most promising candidate gene(s) will be finally used to develop a cisgenic fire blight resistant apple plant. Furthermore the identification and characterization of downstream acting genes and proteins of Mr5 differentially expressed after inoculation with wild type and mutant pathogen strains will be analyzed to get more knowledge about the mechanisms of fire blight resistance.