International Journal of Horticulture, 2015, Vol.5, No.21, 1-45
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Iwata et al. (2000) did RAPD analysis to clarify the origin of Damask roses. DNA analysis of the Damask
varieties proved that they had an identical profile, indicating they were established from a common ancestor. They
have never been allowed to reproduce sexually; their reproduction depends entirely on vegetative propagation.
They identified three
Rosa
species,
R. moschata
,
R. gallica
and
R. fedschenkoana
, as parental species of the
original hybridization that contributed to forming the four oldest Damask varieties by sequencing the internal
transcribed spacer of ribosomal DNA.
AFLP markers were used to estimate the level of heterozygosity in the progrnies of two segregating populations
obtained from crosses made between a parthenogenetic diploid
Rosa hybrida
L. used as female and two diploid
botanic species (
Rosa wichuraiana
Crép. and
Rosa rugosa
Thunb.) used as pollinators. Ninety four percent and 41%
of the AFLPs analysed were found heterozygous in
R. wichuraiana
and
R. rugosa
, respectively (Crespel et al.,
2001).
The genetic diversity among 128 Iranian
Rosa persica
accessions was analyzed using AFLP technique. The
results did not show relative agreement with the genotypes’ region of origin. Analysis revealed that Iranian
R.
persica
genotypes are highly variable and genetically distinct from their origins (Basaki et al., 2009).
Authors (Datta and Chakrabarty, unpublished) studied RAPD of original rose cultivars and their gamma ray
induced flower colour mutants. Out of 20 primers screened, 14 primers yielded completely identical fragments
patterns. Other seven primers gave highly polymorphic banding patterns among the radiomutants (Table 2). The
percentage of polymorphism varied from 50 (P31) to 100% (P4 and P34). PCR amplification with primer P4
clearly revealed that three bands (500, 700, 800 bp) were absent in ‘Contempo Stripe’ as compared to the other
‘Contempo’ mutants (Figure 2A, Lane 4). Similarly in ‘Contempo New’, a highly specific band of 900 bp was
absent in comparison to other mutants when amplified with primer P40 (Figure 2B, Lane 2). In case of ‘Imperator’
(parent), two highly specific bands (400 and 2200 bp) were noticed when genomic DNA was amplified with P4
primer (Figure 2A, Lane 7). Similarly, a polymorphic band of 600 bp was absent in parent cultivar ‘Frist Prize’
(parent) but present in its mutant, when RAPD marker P40 was used (Figure 2B, Lane 10). Amplification with
primer P31 indicated a highly distinct and polymorphic band (800 bp) present only in ‘American’s junior Miss’,
but absent in its mutant ‘Sukumari’, which can be used as a specific marker (Figure 2C, Lane 13-14) . A highly
polymorphic band (800 bp) was present in the mutant cultivar of ‘Sylvia White’ when the RAPD marker P31 was
used (Figure 2C, Lane 15). Similarly two highly distinct polymorphic bands (500 and 800 bp) were present in the
parent cultivar ‘Sylvia’, which can be used to differentiate between the parent and its mutant when the RAPD
marker P34 was used. The parent cultivar ‘Mrinalini’ and its mutant ‘Mrinalini lighter’ could not be distinguished
by any primer tested. However, ‘Mrinalini Stripe’ could be distinguished from its parent and ‘Mrinalini lighter’
when RAPD marker P4 and P40 were used. Based on the presence or absence of the 48 polymorphic bands, the
genetic variations within and among the 18 cultivars were measured. Genetic distance between all 18 cultivars
varied from 0.40 to 0.91, as revealed by Jaccard’s coefficient matrix. Dendrogram was constructed based on the
similarity matrix using Neighbor Joining Tree method showed three main clusters. Cluster A consists of ‘Mrinalini’
and its mutants. Cluster B consists of two subclusters, one subcluster consists of ‘Contempo’ and its mutants and
the other contains ‘Imparator’ and its mutant. ‘Sylvia’ and its mutant have been placed in two different subclusters,
indicating high genetic diversity from its parent which may be due to larger genomic rearrangements due to
gamma irradiation. ‘First Prize’ and ‘American’s Junior Miss’ and their mutants were placed in cluster C. Cluster
analysis separated rose mutants into different groups but genetic distance observed between them was low. In the
present study most of the mutants appeared to be phenotypically same as parents, except flower colour. To clarify
to what extent this phenotypical variation was related to the genetic level, present RAPD analysis showed
noticeable differences between parents and their mutants. This indicated that somatic flower colour changes could
have resulted due to some sort of genomic rearrangements rather than point mutations. The present RAPD
analysis can be used not only for estimating genetic diversity present in different floricultural crops but also for
correct identification of mutant/new varieties for their legal protection under plant variety right.
