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symbiosis can be established and productivity similar to inorganic fertilization can be
obtained under saline conditions.
Plasmid-mediated salt resistance may be ecologically important since resistance can be
rapidly transferred from resistant to sensitive bacteria (Lawlor et al., 1999). Weaver and Holt
(1990) showed that some rhizobial plasmids influenced survival under stress conditions. Our
results also opened new perspectives for the improvement of the
Rhizobium
-legume
symbiosis since plasmid profile analysis suggests that the extrachromossomal genome
contributes to survival in saline habitats. Protein profile alterations induced by salt did not
reflect a common trend. Protein pools of tolerant strains were only slightly affected,
suggesting the putative presence of tolerance mechanisms.
A
CKNOWLEDGMENTS
The authors wish to thank to Dr. Robert Grace for his revision of the English language.
This work was supported by a grant from the Centre for Cell Biology.
5.
R
EFERENCES
Abd-Alla, MH; Vuong, TD; Harper, JE. Genotypic differences in dinitrogen fixation response
to NaCl stress in intact and grafted soybean.
Crop Science
, 1998 38, 72-77.
Abedelgadir, AH; Alexander, M. Procedure to enhance heat resistance of
Rhizobium
.
Plant
and Soil
, 1997 188, 93-100.
Abdelmoumen, H; Filali-Malouf, A; Neyra, M; Belabed, A; El-Idrissi, MM. Effect of high
salt concentrations on the growth of rhizobia and responses to added osmotica.
Journal of
Applied Microbiology
, 1999 86, 889-898.
Athar, M; Johnson, DA. Effects of drought on the growth and survival of
Rhizobium meliloti
strains from Pakistan and Nepal.
Journal of Arid Environment
, 1997 35: 335-340.
Bååth, E. Measurement of heavy metal tolerance of soil bacteria using thymidine
incorporation into bacteria extracted after homogenization-centrifugation.
Soil Biology
and Biochemistry
, 1992 24, 1167-1172.
Bååth, E; Díaz-Ravina, M; Frostegård, Å; Campbell, CD. Effect of metal-rich sludge
amendments on the soil microbial community.
Applied and Environmental Microbiology
,
1998 64, 238-245.
Baldani, JI; Weaver, RW. Survival of clover rhizobia and their plasmid-cured derivates in soil
under heat and drought stress.
Soil Biology and Biochemistry
, 1992 24, 737-742.
Baldani, JI; Weaver, RWM; Hynes, MF; Early, BD. 1992. Utilization of carbon substrates,
electrophoretic enzyme patterns and symbiotic performance of plasmid-cured clover
rhizobia.
Applied and Environmental Microbiology
, 1992 58, 2308-2314.
Boivin, C; Barran, LR; Malpica, CA; Rosenberg, C. 1991. Genetic analysis of a region of the
Rhizobium meliloti
psym specifying catabolism of trigonelline, a secondary metabolite
present in legumes.
Journal of Bacteriology
, 1991
173, 2809-2817.
