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|Title: ||The Symbiotic Performance of Chickpea Rhizobia Can Be Improved by Additional Copies of the clpB Chaperone Gene|
|Authors: ||Paço, Ana|
Mateos, Pedro F.
|Issue Date: ||2016|
|Citation: ||Paço, Ana; Brígido, Clarisse; Alexandre, Ana; Mateos, Pedro F.; Oliveira, Solange. The Symbiotic Performance of Chickpea Rhizobia Can Be Improved by Additional Copies of the clpB Chaperone Gene, PLOS ONE, 11, 2, e0148221-e0148221, 2016.|
|Abstract: ||The ClpB chaperone is known to be involved in bacterial stress response. Moreover, recent
studies suggest that this protein has also a role in the chickpea-rhizobia symbiosis. In order
to improve both stress tolerance and symbiotic performance of a chickpea microsymbiont,
the Mesorhizobium mediterraneum UPM-Ca36T strain was genetically transformed with
pPHU231 containing an extra-copy of the clpB gene. To investigate if the clpB-transformed
strain displays an improved stress tolerance, bacterial growth was evaluated under heat
and acid stress conditions. In addition, the effect of the extra-copies of the clpB gene in the
symbiotic performance was evaluated using plant growth assays (hydroponic and pot trials).
The clpB-transformed strain is more tolerant to heat shock than the strain transformed
with pPHU231, supporting the involvement of ClpB in rhizobia heat shock tolerance. Both
plant growth assays showed that ClpB has an important role in chickpea-rhizobia symbiosis.
The nodulation kinetics analysis showed a higher rate of nodule appearance with the
clpB-transformed strain. This strain also induced a greater number of nodules and, more
notably, its symbiotic effectiveness increased ~60%at pH5 and 83% at pH7, compared to
the wild-type strain. Furthermore, a higher frequency of root hair curling was also observed
in plants inoculated with the clpB-transformed strain, compared to the wild-type strain. The
superior root hair curling induction, nodulation ability and symbiotic effectiveness of the
clpB-transformed strain may be explained by an increased expression of symbiosis genes.
Indeed, higher transcript levels of the nodulation genes nodA and nodC (~3 folds) were
detected in the clpB-transformed strain. The improvement of rhizobia by addition of extracopies
of the clpB gene may be a promising strategy to obtain strains with enhanced stress
tolerance and symbiotic effectiveness, thus contributing to their success as crop inoculants,
particularly under environmental stresses. This is the first report on the successful improvement
of a rhizobium with a chaperone gene.|
|Other Identifiers: ||1932-6203|
|Appears in Collections:||BIO - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica|
MED - Publicações - Artigos em Revistas Internacionais Com Arbitragem Científica
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