福建省放线菌结瘤植物共生菌Frankia遗传多样性研究

[目的]了解福建省放线菌结瘤植物共生固氮菌Frankia的遗传多样性.[方法]利用16S-23SrDNA间隔区(rrn)和nifD-K基因间隔区的PCR扩增和RFLP技术,分析了福建省木麻黄、杨梅、桤木、胡颓子等共生Frankia纯培养菌株的遗传差异.[结果]17个菌株获得rrn扩增片段,2个杨梅菌株和1个胡颓子菌株扩增未成功,酶切图谱经聚类分析表明6个地点的细枝木麻黄、短枝木麻黄、粗枝木麻黄12个共生Frankia菌株同源性高,属于一个类群,2个地点的4个杨梅菌株和1个四川桤木菌株亲缘关系近,为另一类群.25个Frankia菌株的,nifD-K基因间隔区PCR-RFLP分析结果显示,7个地点的3种木麻黄14个菌株聚类为一个类群,4个地点的7个杨梅菌株、2个地点的2个四川桤木菌株以及1个台湾桤木菌株聚类为另一个类群,胡颓子菌株则为独立的类群.[结论]研究结果表明福建省共生Frankia遗传多样性丰富.

Genetic Diversity of Frankia in Fujian

Abstract: There are lots of actinorhizal plants distributed in coastal area and mountains in Fujian province, China. [Objective] The aim of this study is to describe the genetic diversity of Frankia strains symbiotically associated with several species of Casuarina, Myrica, Alnus and Elaeagnus in Fujian. [Methods] Genomic DNA was extracted from Frankia strains and used as template in PCR with the primers targeting two DNA regions, one in ribosomal operon, and the other in nif D-K gene. PCR products were then digested by using a set of restriction endonucleases to generate the restriction fragment length polymorphism patterns. [Results] Except 2 strains nodulating M. rubra and a strain infecting E. oldhami, 17 Frankia strains had an amplified fragment of rrn region in 16S-23S rDNA intergenetic spacer (IGS), 12 Frankia strains nodulating C. equisetifolia, C. cunninghamiana and C. glauca living in 6 geographical origins had high homogeneity and were assigned to one group by clustering analysis, 5 strains from M. rubra and A. cremastogyne were closely related and fell to the other group. All 25 Frankia strains showed a single copy of IGS nif D-K and generated 8 PCR-RFLP patterns while clustering into 3 different groups. Frankia strains nodulating three species of Casuarina in seven different sites had a high degree of genetic similarity to cluster one group. Isolates infecting M. rubra, A. cremastogyne and A. formosana were closely related and belonged to the other cluster, Frankia from E.oldhami owed a quite different cluster. [Conclusion]These results demonstrated that there is great genetic diversity among Frankia microsymbionts in Fujian.