Genetic Diversity of Frankia in Fujian

Abstract:

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.