GENETIC DIVERSITY OF DATISCA CANNABINA-COMPATIBLE FRANKIA STRAINS AS DETERMINED BY SEQUENCE-ANALYSIS OF THE PCR-AMPLIFIED 16S RIBOSOMAL-RNAGENE

The presence of Frankia strains in soil samples collected from norther n areas of Pakistan was detected by inoculating Coriaria nepalensis an d Datisca cannabina plants. The abundance of compatible Frankia strain s in some areas was indicated by profuse nodulation of the host plants , whereas soil samples from other localities failed to result in nodul ation. An oligonucleotide probe (COR/DAT) directed against the 16S rRN A gene of the endophytes of Coriaria and Datisca spp. that did not cro ss-react with the RNA gene of Frankia strains isolated from other host s was developed. Genetic diversity among Frankia strains nodulating D. cannabina was determined by sequence analysis of the partial 16S rRNA gene amplified from nodules induced by soil samples from different lo calities by PCR. Four types of Frankia sequences and one non-Frankia s equence were detected by hybridization with a Frankia genus probe and the COR/DAT probe as well as by sequence analysis of the cloned PCR pr oducts.