International Journal of Horticulture, 2015, Vol.5, No.21, 1-45
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UPGMA dendrogram nor the PCA analysis exhibited strict relationship with geographic distribution and
morphotypes among the accessions.
Huge genotypic variability has been developed in
Opuntia
via natural hybridization associated with polyploidy
and geographical isolation (Gibson and Nobel, 1986). Wang et al. (1998) did experiment with eight
Opuntia
accessions (five cactus fruit varieties from Mexico and Chile, two ornamental Texas accessions, and one vegetable
accession from Mexico) using RAPD to determine whether polymorphism was sufficient to distinguish
Opuntia
accessions and to assess the patterns of genetic diversity among a selected group of accessions. Phenotypic and
molecular analyses distinguished ornamental, vegetative, and fruit market accessions of
Opuntia
from each other,
and suggested significant differences among accessions of different market classes. The experiment demonstrates
the potential usefulness of molecular markers in classification of cactus accessions, and indicated the feasibility of
a comprehensive effort to determine the relationships among
Opuntia
species using molecular markers.
Ko et al. (1996) studied genetic diversity of 6 most important cultivars of popular flowers of
Ozothamnum
diosmifolius
(Vent.) DC by RAPD using 19 arbitrary primers.
Fajardo et al. (1998) analyzed genetic variation of 52 accessions representing 14 species of the genus
Passiflora
L.
by RAPD using 50 random primers.
Palumbo et al. (2007) tested the feasibility ofTarget region amplification polymorphism (TRAP) for molecular
characterization of Pelargonium collections comprising cultivars, breeding lines and wild species. On the basis of
their observations, they mentioned that TRAP is an effective method for molecular characterization of ornamental
collections and this will help to retain the most diverse genotypes and to use as genetic markers in future breeding
programme.
Peltier et al. (1994) established the first linkage map for
Petunia hybrida
based upon both RAPD and phenotypical
markers. They also applied RAPD markers on a set of ten P. hybrida, lines chosen for their diversity and on a set
of seven wild species corresponding to the possible ancestors of the
P. hybrida
species.
RAPD profiles of thirteen rhododendron hybrids, species and cultivars were analyzed to study their genetic
relationships. The cluster analysis grouped together varieties and/or hybrids in accordance with their known
genetic relationship. The genetic relationship revealed from cluster analysis on the basis of RAPD profiles was
similar to their known genetic makeup (Iqbalet al., 1995).
Menziesia, a small genus in Ericaceae bear small bell-shaped flowers, which is white, yellow, pink or brick red
colors in spring-summer time. Handa et al. (2003) analyzed sequences of both chloroplast
matK
gene and nuclear
internal transcribed spacer (ITS) region from genus
Rhododendron
and its closely related genera including
Menziesia
. Results revealed that
Menziesia
is nested within the genus
Rhododendron
.They tried to make new
intergeneric hybrids between
Menziesia
and
Rhododendron
by crossing. In an orchid genus
Dendrobium
, section
Callista
includes many attractive species but the flower-vase-life is relatively short. They also analyzed both
matK
and ITS sequence of section
Callista
and its related sections in
Dendrobium
. Results indicated that other sections
such as
Calyptrochilus
and
Pedilonum
, which have long-lasting flowers, are closely related to section
Callista
. On
the basis of this phylogenetic information, they successfully obtained intersectional hybrids of section
Callista
with these other sections. Phylogenetic information is useful for the exploitation of ornamental germplasm
in introducing novel resources or selecting closely related species for the introgression of horticultural interesting
traits.
In the International Union for the Protection of New Varieties of Plants Act of 1991, mutation is mentioned as one
of the mechanisms to obtain an ‘essentially derived’ variety (EDV). For the implementation of the EDV concept in
the case of mutation, it is important that the level of genetic relatedness between an initial variety and derived
mutant varieties can clearly be distinguished from the level of relatedness between arbitrary pairs of varieties
without a derivation relation. In rose, mutants or ‘sports’ are frequently observed during multiplication, making it
a suitable crop for studying the possibilities for introduction of the EDV concept in ornamentals. Vosman et al.
