Characterisation of Agrobacterium spp. isolated from Eucalyptus crown gall tumors
2002
Krimi, Zoulikha | Raio, A. | Nesme, Xavier | Dessaux, Y.
The prospecting performed in a forest nursery located in Tlemcen (western Algeria) recorded 60 000 seedlings, two years old of Eucalyptus occidentalis affected by crown-gall. Only this nursery showed symptoms of crown gall at this time of sampling and had not reported symptoms of crown gall on all the seedlings cultivated in the previous years. The tumor size of the infected seedlings ranged from 5 to 25 min of diameter, they were verrucous, color varies from white to brown and were located at the crown. Several seedlings digged up, showed no evidenced tumors on the roots. The representative symptoms were found only on E. occidentalis and not on E. camaldulensis nor on E. cladocalyx also co-cultivated in the same conditions Bacteria isolated from tumors of galled Eucalyptus occidentalis seedlings were typical Agrobacterium spp. Biochemical characterization of twenty (20) isolates, indicated the presence of only biovar 1 Agrobacterium strains. Pathogenicity testing of the present population on tested hosts produces tumors on wounded tissues. Molecular analysis by PCR using Vir and tmr primers indicated the presence of Ti plasmid homologous sequences. Analysis of synthesized opines on induced tumors and in-vitro sensitivity to agrocin 84, revealed that nopaline plasmid-type is the only plasmid represented. Crowngall of Eucalyptus has been for the first time reported, this species is ordered now, in the large host range of this bacterium. (Texte intégral)
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