Basic HTML Version
Molecular Plant Breeding 2012, Vol.3, No.2, 11
-
25
http://mpb.sophiapublisher.com
12
gov.in/html/reports/commercial/2010-11_10PA/chap
10.pdf). In recent years the importance of jute crop
has increased further due to its use in diversified value-
added industrial products and packaging materials
(Mondal, 2000).
The yield and quality of jute fibre need to be improved
further through redesigning of breeding programs to
allow its successful competition with widely and
abundantly used synthetic fibres. However, only very
limited number of indigenous and exotic jute accessions
representing only a narrow range of genetic variability
have been exploited so far in jute breeding programs
(Roy et al., 2006). Early success in varietal development
of tossa jute was achieved through utilization of an
African genotype “Sudan green”, while induced
mutations were the major source for varietal develop-
ment of white jute. Until 2010, only 16 varieties of
C. capsularis
and 15 varieties of
C. olitorius
were
released in India, mainly following intra-specific
hybridization (Kar et al., 2010). Therefore, there is a
need for the use of newer and diverse germplasm for
jute improvement programs.
C. capsularis
has fine fibre with slightly weak strength.
It is relatively resistant to flood and drought and also
susceptible to diseases and pests. In contrast,
C.
olitorius
has stronger and lustrous fibre and is also
more resistant to diseases and pests, although it is
susceptible to abiotic stresses like flood and drought.
Therefore, ideally a desirable approach for jute
improvement would be to combine the contrasting
features of the two species into a single genotype.
However, these two species are cross incompatible
precluding inter-specific hybridization for combining
the desirable traits (Patel and Datta, 1960; Swaminathan
et al., 1961). Therefore, only intra-specific hybridization
involving diverse germplasm may be used for
producing improved varieties belonging to each of
these two commercially important species of jute.
Although a large collection of 939 accessions of
C.
capsularis
and 1 647 accessions of
C. olitorius
is
available at Central Research Institute for Jute and
Allied Fibres (CRIJAF), Barrackpore, Kolkata, India,
but systematic and planned efforts have seldom been
made to study genetic diversity in the available
germplasm of the two cultivated species. Also, genetic
diversity in jute was studied in the past using only
morpho-physiological traits such as plant height,
harvest index, cambial activity and fibre strength
(Palit et al., 1996). These traits are limited in number
and are often influenced by the environment, and
therefore, may not be suitable for correct assessment
of the genetic diversity. This limitation can be largely
overcome by the use of molecular markers, which are
unlimited in number and are not influenced by the
environment.
The molecular markers have been widely used for the
study of genetic diversity in almost all crops (Prasad
et al., 2000; Malysheva-Otto et al., 2006; Mazzucato
et al., 2008; Wen et al., 2009; Ming et al., 2010; Zarkti
et al., 2010; Mir et al., 2011). In jute, molecular
markers like RAPDs, chloroplast-SSRs, gSSRs, ISSRs,
and AFLPs have been used to assess genetic diversity
in both cultivated and wild species (Qi et al., 2003a;
2003b; Hossain et al., 2002a; 2003b; Basu et al., 2004;
Roy et al., 2006; Haque et al., 2007; Mir et al., 2008a;
Mir et al., 2008b; Akter et al., 2008; Huq et al., 2009).
However, these studies were carried out on rather
small collections of up to 81 genotypes of cultivated
and wild species giving only very limited idea about
the genetic diversity available in the gene pool of the
two cultivated species of jute. The present study on
genetic diversity and population structure was
conducted using a relatively larger and more diverse
set of 292 jute genotypes (152 genotypes of
C.
capsularis
and 140 genotypes of
C. olitorius
) from
both indigenous and exotic collections with the help
of 172 genomic SSRs.
1 Results
1.1 SSR polymorphism
Genotyping of all the 292 jute genotypes including
152 genotypes of
C. capsularis
and 140 genotypes of
C. olitorius
was carried out using a set of 167 SSR
primers which identified 172 polymorphic SSR loci
carrying 596 alleles (3.45 alleles per locus, range 2~7
alleles). Out of the 172 polymorphic loci, 8 loci
(4.65%) exhibited only inter-specific polymorphism
and were bi-allelic, one allele for each of the two
species and 93 SSR loci (~54%) accounted for 150
alleles shared by the both species. The remaining 71
loci (41.27%) exhibited both inter and intra-specific