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Fire blight resistance of the wild apple species Malus fusca: mapping, gene isolation and functional characterization

野生苹果品种 Malus fusca 的火疫病抗性：定位、基因分离和功能表征

基本信息

批准号：
275614283
负责人：
Dr. Andreas Peil
金额：
--
依托单位：
Institut für Züchtungsforschung an Obst
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2015
资助国家：
德国
起止时间：
2014-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/275614283?language=en
关键词：
Fire blight resistance wild apple

项目摘要

Fire blight, caused by the Gram-negative bacterium, Erwinia amylovora, is the most destructive bacterial disease of apple (Malus ×domestica). The economic impacts as a result of fire blight epidemics are usually huge, reaching millions of dollars. The application of antibiotics is the most effective control measure available to apple growers. However, this measure is unsustainable and forbidden in Germany. An alternative measure is therefore inevitable. Natural resistance is thought to be the most sustainable approach to manage fire blight. Genetic resistance has been investigated in Malus leading to the detection of several quantitative trait loci (QTLs) in apple cultivars and apple wild species accessions. Nevertheless, only one functionally characterized fire blight resistance gene, FB_MR5, underlying the Malus ×robusta 5 (Mr5) QTL, has been isolated till date. The situation is more critical since it has been proven that resistance of Mr5 is strain specific and completely broken down by a highly virulent strain of E. amylovora (Ea3049) and an avrRpt2EA effector deletion mutant (ZYRKD3-1). The exchange of only one amino acid in this effector protein or its loss is responsible for the breakdown of resistance of Mr5. It is therefore crucial to identify more resistant donors and to isolate the underlying resistance genes in order to functionally characterize them and to finally establish durable resistance through pyramiding of mechanisms acting differentially. Consequently, resistance to fire blight was investigated in the wild apple species Malus fusca, which resulted in the identification of a major QTL on linkage group 10 (LG10) which explained about 66 % of the phenotypic variation. In contrast to Mr5 the M. fusca QTL (Mfu10) was not overcome after inoculation with isolate Ea3049. The objective of this research proposal is to isolate and functionally characterize the gene(s) underlying Mfu10. A population of 1,336 progeny individuals was established for a fine mapping approach. Genotyping with closely linked SSR markers has allowed for the identification of individuals showing recombination within the QTL interval. Recombinant individuals will form the basis for the isolation of the gene. To study the interaction of Mfu10 with the avrRpt2EA effector, the mapping population will be phenotyped with ZYRKD3-1 and an avrRpt2EA deletion mutant of strain Ea3049 and the respective complemented strain. Additionally, preliminary results suggest that another resistance locus in M. fusca or minor QTLs are contributing to the resistance of M. fusca. Therefore, to precisely detect these loci, the completion and saturation of the M. fusca genetic map is necessary. Overall, it is expected that the underlying resistance genes of M. fusca will provide resistance against the highly virulent E. amylovora isolates responsible for the breakdown of the Mr5 QTL and that pyramiding of these factors together with FB_MR5 will provide more durable resistance.

苹果火疫病是由革兰氏阴性细菌梨火疫病菌（Erwiniamylovora）引起的苹果细菌性病害。火疫病流行造成的经济影响通常是巨大的，达到数百万美元。抗生素的应用是苹果种植者最有效的防治措施。但这一措施在德国是不可持续和禁止的。因此，采取替代措施是不可避免的。自然抗性被认为是最可持续的方法来管理火疫病。对苹果属植物的遗传抗性进行了研究，并在苹果栽培品种和野生种中检测到了多个数量性状基因座（QTL）。然而，迄今为止，只有一个功能特征的火疫病抗性基因，FB_MR5，潜在的Malus ×robusta 5（Mr 5）QTL，已被分离。由于已经证明Mr 5的抗性是菌株特异性的，并且完全被E. amylovora（Ea 3049）和avrRpt 2 EA效应子缺失突变体（ZYRKD 3 -1）。该效应蛋白中仅一个氨基酸的交换或其丢失负责Mr 5抗性的破坏。因此，至关重要的是，以确定更多的耐药供体和分离潜在的耐药基因，以功能上表征他们，并最终建立持久的耐药性，通过消除机制的差异。因此，在野生苹果种Malus fusca中调查了火疫病抗性，这导致在连锁群10（LG 10）上鉴定了一个主效QTL，其解释了约66%的表型变异。与Mr 5相比，M.接种Ea 3049菌株后，fusca QTL（Mfu 10）未被克服。本研究计划的目的是分离和功能表征Mfu 10的基因。建立了1，336个后代个体的群体用于精细作图方法。利用紧密连锁的SSR标记进行基因分型，可以鉴定在QTL区间内显示重组的个体。重组个体将形成分离基因的基础。为了研究Mfu 10与avrRpt 2 EA效应子的相互作用，将用菌株Ea 3049的ZYRKD 3 -1和avrRpt 2 EA缺失突变体以及相应的互补菌株对作图群体进行表型分析。此外，初步结果表明，在M. fusca或次要QTL对稻瘟病菌的抗性起作用。褐色。因此，为了精确地检测这些位点，M. fusca遗传图谱是必要的。总体而言，预计潜在的抗性基因的M。fusca将提供对高毒力E.这些因子与FB_MR5一起的消除将提供更持久的抗性。