Characterization of eds1, a mutation in Arabidopsis suppressing resistance to Peronospora parasitica specified by several different RPP genes
Characterization of eds1, a mutation in Arabidopsis suppressing resistance to Peronospora parasitica specified by several different RPP genes
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DOI：
10.1105/tpc.8.11.2033
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发表时间：
1996-11-01
期刊：
影响因子：
11.6
通讯作者：
Daniels, MJ
中科院分区：
文献类型：
--
作者：
Parker, JE;Holub, EB;Daniels, MJ
拟南芥与寄生真菌霜霉病菌(Peronospora Parasitica)之间的相互作用为鉴定寄主的分子成分提供了一个诱人的模式，这些分子成分是识别寄主的基因特异性所必需的。这些成分就是所谓的RPP基因(用于抗疫霉菌)。对生态型Wassilewski ja(Ws-0)的突变分析显示，在第3染色体(RPP1/RPP14和RPP10)和第4染色体(RPP12)上的RPP基因功能所必需的一个称为EDS1(增强疾病敏感性)的RPP非特异性基因座。遗传分析表明，eds1突变是隐性的，不是任何已知RPP基因的缺陷等位基因，定位于3号染色体的底臂(类似于RPP1/RPP14下方的13个厘米器官)。在表型上，Ws-eds1突变体幼苗支持寄生疫霉菌株的大量产孢量，每个菌株对野生型Ws-0中的一个RPP基因具有诊断作用；没有一个菌株能够在野生型Ws-0上产孢。与亲和野生型Columbia和亲本eds1生态型Ws-0相比，WS-eds1幼苗对某些寄生疫霉分离物表现出更强的敏感性。这是因为孢子形成较早，分生孢子囊产量增加。令人惊讶的是，Ws-eds1的子叶也支持来自甘蓝的5个寄生孢子分离物的低产孢量。这些分离物不能在包括野生型Ws-0在内的>；100生态型拟南芥上产生孢子。一株白念珠菌(白色水泡)也在Ws-eds1上产生孢子，但与其他寄主的几个卵菌菌株接种后，突变体的表型没有发生变化。细菌抗性基因rpm1在Ws-eds1植物中不被攻克，该基因对丁香假单胞菌的无毒基因avrB具有特异性识别作用。突变体对系统获得抗性的化学诱导剂2，6-二氯异烟酸也保持了完全的反应性，经2，6-二氯异烟酸处理的Ws-eds1幼苗分别对Ws-0亲和和Ws-0不亲和的寄生疫霉菌株Emwa1和Noco2产生抗性。综上所述，EDS1基因似乎是由几个RPP基因指定的抗性反应的必要组成部分，并且可能在拟南芥的抗病途径的汇聚的上游发挥作用。
The interaction between Arabidopsis and the biotrophic oomycete Peronospora parasitica (downy mildew) provides an attractive model pathosystem to identify molecular components of the host that are required for genotype-specific recognition of the parasite. These components are the so-called RPP genes (for resistance to P. parasitica). Mutational analysis of the ecotype Wassilewskija (Ws-0) revealed an RPP-nonspecific locus called EDS1 (for enhanced disease susceptibility) that is required for the function of RPP genes on chromosomes 3 (RPP1/RPP14 and RPP10) and 4 (RPP12). Genetic analyses demonstrated that the eds1 mutation is recessive and is not a defective allele of any known RPP gene, mapping to the bottom arm of chromosome 3 (similar to 13 centimorgans below RPP1/RPP14). Phenotypically, the Ws-eds1 mutant seedlings supported heavy sporulation by P. parasitica isolates that are each diagnostic for one of the RPP genes in wild-type Ws-0; none of the isolates is capable of sporulating on wild-type Ws-0. Ws-eds1 seedlings exhibited enhanced susceptibility to some P. parasitica isolates when compared with a compatible wild-type ecotype, Columbia, and the eds1 parental ecotype, Ws-0. This was observed as earlier initiation of sporulation and elevated production of conidiosporangia. Surprisingly, cotyledons of Ws-eds1 also supported low sporulation by five isolates of P. parasitica from Brassica oleracea. These isolates were unable to sporulate on >100 ecotypes of Arabidopsis, including wild-type Ws-0. An isolate of Albugo candida (white blister) from a oleracea also sporulated on Ws-eds1, but the mutant exhibited no alteration in phenotype when inoculated with several oomycete isolates from other host species. The bacterial resistance gene RPM1, conferring specific recognition of the avirulence gene avrB from Pseudomonas syringae pv glycinea, was not compromised in Ws-eds1 plants. The mutant also retained full responsiveness to the chemical inducer of systemic acquired resistance, 2,6-dichloroisonicotinic acid; Ws-eds1 seedlings treated with 2,6-dichloroisonicotinic acid became resistant to the Ws-0-compatible and Ws-0-incompatible P. parasitica isolates Emwa1 and Noco2, respectively. In summary, the EDS1 gene appears to be a necessary component of the resistance response specified by several RPP genes and is likely to function upstream from the convergence of disease resistance pathways in Arabidopsis.