Abstract:
Robust information of genetic diversity among
Bt
cotton genotypes is still lacking and
availability of several marker systems has prompted
us to compare their utility for the
detection of genetic diversity. Here, we report the
comparative efficiency of morphological
and molecular markers (EST-SSRs and ISSRs) in deter
mining the genetic diversity
among 30 Pakistani
Bt
cotton genotypes. Three different dendrograms base
d on 20 EST-
SSRs, 13 ISSRs and 20 morphological markers divided
the 30
Bt
cotton genotypes into
five, six, and three clusters, respectively. EST-SS
Rs and ISSRs revealed 0.73-1.00 and
0.77-0.97 genetics similarity among
Bt
cotton genotypes which indicated low level of
genetic diversity. Further population structure ana
lysis showed extensive allelic
admixture among
Bt
cotton cultivars and identified three (EST-SSRs) a
nd six (ISSRs)
subgroups. The MGHES-31 (EST-SSRs) and UBC-807 and
UBC-815 (ISSRs) showed
maximum values of Polymorphic Information Contents
(
PIC
) and
Dj
and had low value
of
Cj
. The comparison of two marker systems showed that
EST-SSRs had high value of
Expected heterozygosity (H
ep
) and low value of Marker Index (MI) as compared to
ISSRs.
In conclusion, high level of genetic similarity amo
ng
Bt
cotton genotypes compel the plant
breeders for the introduction of divers/exotic geno
types in their breeding program and
marker discriminating indices could be a potential
tool for selection of particular marker
system to unveil the genetic difference.
Keywords:
Confusion probability, Expected heterozygosity, Ma
rker Index, Population
structure analysis, Polymorphic information content
s.
