DNA FINGERPRINTING AND DIVERSITY ANALYSIS OF NERIUM (Nerium oleander L.) CULTIVARS AND HYBRIDS
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Date
2021-01
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University of Horticultural Sciences, Bagalkot. (College of Horticulture, Bagalkot).
Abstract
An experiment entitled ‘DNA fingerprinting and diversity analysis of Nerium
(Nerium oleander L.) cultivars and hybrids’ was conducted at Department of
Floriculture and Landscape Architecture, College of Horticulture, Bagalkot, University
of Horticultural Sciences, Bagalkot during the 2018 to 2020. Evaluation of nerium
cultivars for growth and qualitative traits, floral biology, in vivo pollen germination and
pollen pistil interaction were investigated. Fourteen direct intervarietal cross
combinations were conducted, fruit setting and seed germination behaviour of different
cross combinations were studied. In vitro inter varietal immature seed culture was
studied. The DNA fingerprinting as well as diversity analysis of nerium cultivars and
hybridity conformation at molecular level were investigated.
The results revealed that maximum value for plant growth increment UHSBN10 (226.20 cm), plant spread in East-West UHSBN-29 (199.79 cm), plant spread in
North-South UHSBN-13 (201.47 cm), number of primary branches UHSBN-27 (6.03),
number of secondary branches UHSBN-1 (13.28), inter nodal length UHSBN-29 (5.40
cm), leaf length UHSBN-29 (23.50 cm), leaf width UHSBN-12 (3.02 cm) and petiole
length UHSBN-21 (1.16 cm) were recorded in the nerium cultivars. Maximum mean
number of inflorescence per plant UHSBN-12 (27.92), number of flowers per
inflorescence UHSBN-2 (90.23), bud length UHSBN-13 (3.28 cm), corolla tube length
UHSBN-13 (1.22 cm), flower diameter UHSBN-18 (5.86 cm), individual flower weight
UHSBN- 27 (1.40 g), hundred flower weight UHSBN-27 (139.90 g) and yield per plant
UHSBN-17 (4.92 kg) were recorded in the prasent investigation.
Anthesis, anther dehiscence and stigma receptivity were observed during the
morning hours. Irrespective of nerium cultivars, pollen viability (88.77 to 97.90 %) and
quality of the pollen grains (61.20 to 77.12 %) was good, it is suggesting that all the
studied cultivars can be used as male parent in hybridization programme. Observation
of stigmatic papillae under florescent microscope reveals that presence of herkogamy in
the nerium. Receptive area on the stigmatic papillae was restricted in nerium which was
present at below the stylar ribs on both the sides. In vivo pollen germination and pollen
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pistil interaction by selfing in popular cultivar UHSBN-12 indicates that no barriers
were present. Nerium is self-compatible, but automatic selfing was prevented by the
presence of sticky drop. Most of the pollen tube showing irregular growth, twisting and
branching of pollen tubes were noticed in Double X Double type cultivar crosses. There
was wide variation with respect to pod set was observed and it ranged from 12 to 87.27
% among the different cross combinations. The cross combination UHSBN-14 X
UHSBN -3 was recorded the maximum seed viability per cent (96.66) and maximum
seed germination were noticed in the cross combination UHSBN-12 X UHSBN-14
(66.00 %). By following the immature in vitro intervarietal seed culture it is possible to
reduce the time up to 6 months for one hybridization cycle when compare to traditional
breeding cycle.
Fifteen ISSR primers were used to produce DNA fingerprint profiles of nerium
cultivars. Among the fifteen primers used for the study, eleven primers showed
polymorphism with the 122 loci across thirty neruim cultivars. Out of these loci, 111
loci were polymorphic (89.98 %), reflecting the richallelic diversity in the sampled
populations. Thirty nerium cultivars were clustered into two major clusters by the Mega
X based on the polymorphic bands with total branch length of 382.09. Major cluster-I
consisting of 23 cultivars with total sub tree distance of 272.17 and cluster II consisting
of 7 cultivars with sub tree distance of 109.92. ISSR analysis was carried out in five
randomly selected individuals of nerium F1 hybrids in each cross combination, which
exhibited intermediate characteristics to confirm hybridity on the molecular level. Band
pattern was evaluated and male parent informative bands were present in the sample of
the progeny, were verified as hybrids.