International Journal of Horticulture, 2015, Vol.5, No.21, 1-45
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cultivars. Molecular markers were obtained in every subculture cycle and from the acclimatized plants. Only one
shoot from the 7th subculture of the cultivar ‘Refocus’ showed a different band pattern. The analysis has been
carried out with RAPD markers and different aspects of the culture, as source of explants, media composition and
culture age have been considered. Xu et al. (2006) investigated the genetic diversity of 22 Chrysanthemum
morifolium accessions by RAPD markers. A total of 233 bands were amplified, of which 89.7% bands were
found to be polymophic. The results of cluster analysis by using UPGMA method showed that all the tested
accessions showed much genetic diversity at the molecular level and could be differentiated by RAPD marks.
Sehrawat et al. (2003) examined genetic variation in 13 commercial chrysanthemum (
Chrysanthemum morifolium
Ramat.) cultivars using RAPD markers. A total of 257 clear and reproducible bands were detected of which 239
bands were polymorphic. Genetic variation amongst cultivars was high enough to divide them into two major
groups. These groupings were in consistent with their morphological differences and geographical distribution.
The results indicate that RAPDs are efficient for identification of chrysanthemum cultivars and for determination
of genetic relationships. Teng et al. (2006) studied the genetic variation of regenerated plantlets in chrysanthemum
following
in vitro
mutation using RAPD methods. Results showed that genetic variation of generated plantlet was
proportional to the dosage of gamma ray, while the 15 and 20 Gy treatments were not significantly different,
which was consistent with the common conception that genetic variation of radiomutants was usually proportional
to the dosage of mutagen within a certain range. They concluded that RAPD is a useful technique for the rapid and
easy assessment of genetic variation of mutants and may become a potential tool for the quick selection of
mutants with great genetic variation during early growth stages.
Authors (Chatterjee et al., 2006a, 2006b) selected 47 large flowered varieties, 48 small flowered varieties, 21
mutant varieties and 24 mini varieties of chrysanthemum at random from germplasm collection for molecular
characterization. The objective was to find out the genetic diversity present in the entire chrysanthemum
germplasm in general and large flowered, small flowered and mini chrysanthemum in particular. Special aim was
also to find out the molecular basis of somatic flower colour mutations i.e. how gamma ray induced
morphological mutants (flower colour/shape) can be identified by molecular markers. A total of 50 random
primers were screened and only 10 gave good results which were selected for final RAPD analysis. Some primers
yielded extremely different banding patterns in mutants and parents. Band generated by RAPD fragments are of
low molecular weight ranging from 400 bp to 1500 bp. Bands for each primer ranged from 3-13. All the miniature
varieties look like similar in vegetative stage. Though each and every miniature cultivars could not be
differentiated by these selected primers but it was sufficient to estimate the genetic diversity among the twenty
four cultivars. This result did not show any relation between the geographical distribution and genetic diversity of
species as cultivar ‘Shizuka’ (imported from Japan) show close relation with the local cultivars ‘Little Darling’
and ‘Pancho’. The average diversity among the large flowers was found to be low whch may be due to continuous
selection of superior varieties leading to extinction of some of the cultivars. Dendrogram of large cultivars
indicated two major groups and dendrogram of the small group clearly indicated three groups.
Jackson, et al. (2000) examined how DNA fingerprinting techniques based on PCR amplification of microsatellite
and
Copia
like sequences can be utilized in the Chrysanthemum DUS process. On the basis of their results, they
have discussed the benefits of these approaches.
Kishimoto et al. (2003) studied the variations in chloroplast DNA of
Dendranthema
species by PCR-RFLP
analysis to find out the maternal origin of the cultivated chrysanthemum,
D. grandiflorum
. Ten genes,
atpH, matK,
petA, perB, psaA, rbcL, rpoB, rpoC, trnK
and 16S in the chloroplast DNA of 12 Japanese wild species and 1
cultivar were amplified by PCR. The amplified DNAs that were digested with each of 32 restriction
endonucleases revealed 13 site changes among the 13 species in the following 9 gene plus restriction
endonuclease combinations:
petA-AvaII
,
petA-HaeIII
,
petA-MboII
,
petA-NdeII
,
rpoC-EcoRV
,
trnK-DraI
,
trnK-HinfI
,
trnK-MboII
and
trnK-ScrFI
. No Japanese wild species showed the same PCR-RFLP pattern of
chloroplast DNA as
D. grandiflorum
.
Genetic relationships among Calathea species and cultivars were studied among 34 commonly grown cultivars
