Frankia isolates from different Discaria (Rhamnaceae) species show varied nodulation kinetics depending on the host

CHAIA E; VALVERDE C; WALL LG

CURRENT MICROBIOLOGY

Año: 2006 vol. 53 p. 523 - 528

0343-8651

Frankia BCU110601 (Da) and Frankia BCU110345 (Dc) were isolated from root nodules of Discaria articulata and Discaria chacaye, respectively, Frankia BCU110501 (Dt) was previously isolated from Discaria trinervis. The strains were identical at the 16S sequence and after analysis of RFLP of 16S and 23S rDNA intergenic region. Diversity was revealed at the molecular level after fingerprint analysis by BOX-PCR. The strains were infective and effective on the original host plants. A cross inoculation assay intra Discaria genus, including D. trinervis, D. articulata and D. chacaye, with each of these isolated Frankia strains caused effective symbioses with a similar dry weight in each plant species regardless of the inoculated strain. Nevertheless a differential degree of recognition was revealed: Homologous symbiotic pairs in the case of D. chacaye - Frankia BCU110345 (Dc), D. articulata - Frankia BCU110601 (Da) and D. trinervis - Frankia BCU110501 (Dt) had faster nodulation rate than heterologous pairs.  The differences in nodulation rate would suggest the existence of a subspecific level of recognition within a certain cross-inoculation group, pointing to sub-specific adaptation occurring in this actinorhizal symbiosis.