Bradyrhizobia nodulating the Acacia mangium x A. auriculiformis interspecific hybrid are specific and differ from those associated with both parental species.
In the context of an increasing utilization of the interspecific hybrid Acacia mangium x A. auriculiformis as a plantation tree in the tropical humid zone, its symbiotic characterization was carried out in comparison with that of its two parental species. Rhizobium strains of diverse geographical origins were isolated from root nodules of the hybrid and its parents. Almost all Acacia hybrid isolates were fast growing on yeast extract-mannitol medium, in contrast to those isolated from both parental species, which were mostly slow growing. The rhizobium strains were characterized through partial sequencing of the rRNA operon. In the phylogenetic tree, almost all strains isolated from the hybrid were grouped together in a clade close to Bradyrhizobium japonicum, while all strains isolated from both parental species were close to Bradyrhizobium elkanii. Inoculation experiments performed under in vitro or greenhouse conditions showed that all strains were infective with their original hosts but exhibited very variable degrees of effectivity according to the host plant tested. Thus, homologous strain-host associations were more effective than heterologous ones. This shows that there is still a high potential for isolating and testing new strains from hybrids to be used as inoculants in the context of large-scale afforestation programs.
LSTM, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France.
Christine
C
Le Roux
Diana
D
Tentchev
Yves
Y
Prin
Doreen
D
Goh
Yani
Y
Japarudin
Marie-Mathilde
MM
Perrineau
Robin
R
Duponnois
Odile
O
Domergue
Philippe
P
de Lajudie
Antoine
A
Galiana
D000045:Acacia / Q000235:genetics* / Q000382:microbiology* / Q000502:physiology; D000818:Animals; D044822:Biodiversity; D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D002678:Chimera / Q000235:genetics / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D053204:Root Nodules, Plant / Q000382:microbiology; D012988:Soil Microbiology; D013045:Species Specificity; D013559:Symbiosis
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012335:RNA, Ribosomal