Huguet Valérie, Mergeay Max, Cervantes Emilio, Fernandez Maria P
Laboratoire d'Ecologie Microbienne, UMR CNRS 5557, Université Claude Bernard Lyon1, 43 Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France.
Environ Microbiol. 2004 Oct;6(10):1032-41. doi: 10.1111/j.1462-2920.2004.00625.x.
Myricaceae can be nodulated by a variety of Frankia strains isolated from other actinorhizal families. Consequently, the genus Myrica has been considered to have low specificity with respect to microsymbiont taxa. In contrast to controlled studies of Myrica infectious capacity, field studies in North America have indicated that M. gale symbionts belong to the genetic group of Alnus-infective strains. Myrica gale is the most widely distributed species in the genus so this study focused on describing the genetic diversity of M. gale-nodulating strains from 10 sites in Western Europe across a range of edaphic conditions. When possible, the specificity of M. gale-infective strains was compared with that of Alnus-infective strains from the same sites. Nodular strains from Belgium, France and Spain were characterized using PCR-RFLP of rrs gene and 16S-23S IGS. rrs-RFLP patterns showed a high level of homogeneity among European strains with one dominant genotype. IGS-RFLP patterns revealed the largest inter and intrasite diversity in France. In Belgium, Frankia strains were found to occur in two groups according to soil pH and organic matter characteristics of the sites. European M. gale-infective strains were genetically different from European Alnus and North American M. gale-infective strains indicating the possibility of different pathways of co-evolution among geographically isolated populations.
杨梅科可被从其他放线菌根植物科分离出的多种弗兰克氏菌菌株结瘤。因此，杨梅属被认为对微共生体分类群的特异性较低。与对杨梅感染能力的对照研究相反，北美的田间研究表明，香杨梅的共生体属于桤木感染性菌株的遗传组。香杨梅是该属中分布最广的物种，因此本研究着重描述了西欧10个地点在一系列土壤条件下结瘤香杨梅菌株的遗传多样性。在可能的情况下，将感染香杨梅的菌株与来自同一地点的感染桤木的菌株的特异性进行了比较。使用rrs基因和16S - 23S IGS的PCR - RFLP对比利时、法国和西班牙的根瘤菌株进行了特征分析。rrs - RFLP图谱显示欧洲菌株中具有一种优势基因型，具有高度的同质性。IGS - RFLP图谱揭示了法国最大的种间和种内多样性。在比利时，根据地点的土壤pH值和有机质特征，弗兰克氏菌菌株分为两组。欧洲感染香杨梅的菌株在遗传上与欧洲桤木和北美感染香杨梅的菌株不同，这表明地理隔离种群之间可能存在不同的共同进化途径。
