Abstract:
The normal nodulating chickpea cultivar (HC5) and r
evertant of non-nodulating
cultivar ICC 4993 NN designated as ICC 4993 (R) wer
e used to study and characterize the
rhizobia infecting both cultivars. On the basis of
growth characteristic and nodulation, 43
rhizobial isolates from revertant of non-nodulating
cultivar and 8 rhizobial isolates from
normal nodulating cultivar were selected. Heterogen
eity of the rhizobia infecting both of
the cultivars was estimated by ERIC (Enterobacteria
l Repetitive Intergenic Consensus) as
well as RFLP (Restriction Fragment Length Polymorph
ism) analysis of 16S rDNA
sequence. Based on the presence of different ERIC p
rofiles, rhizobial isolates from cv
.
ICC4993 (R) formed eight different clusters and tho
se from cv
.
HC5 formed three
clusters at 80% similarity. A combined dendrogram o
f all the mesorhizobial isolates from
the two cultivars showed two clusters at 70% simila
rity and eight subclusters at 80%
similarity level. Similarly, RFLP patterns showed t
hat rhizobial isolates from cv
.
ICC4993
(R) formed eleven clusters while those from cv
.
HC5 formed two clusters at 80%
similarity. A combined dendrogram of mesorhizobial
isolates from the two cultivars
formed twelve clusters at 80% level of similarity.
Using both methodologies, heterogeneity
(if any) of mesorhizobia nodulating cvs
.
ICC4993 (R) and HC5 could not be ascertained.
Further sequencing of partially amplified 16S rDNA
of three rhizobial isolate from cv.
ICC4993 (R) and one from cv
.
HC5 showed more than 98% similarity with
Mesorhizobium muleiense
and
Mesorhizobium mediterraneum
. The phylogenetic analysis
of 16S rRNA partial sequence revealed 11 monophylet
ic clades. The isolates NN78 and
HC 1065 were clustered along with
Mesorhizobium mediterraneum
strain PECA20 while
NNs13 and NN90 formed a separate cluster.
Keywords
:
Diversity, ERIC,
Nodulation,
Mesorhizobium
, Phylogenetic analysis, RFLP.
