Developments in the micropropagation of Cocos nucifera L.
File(s)
Author(s)
Hornung, Roland Karl Wilhelm
Type
Thesis
Abstract
The coconut palm {Cocos nucifera L.) is a major crop plant which does not
develop axillary shoots and must therefore be propagated from seed. As it is a
heterozygous outbreeder, seedlings are variable and only after a long juvenile stage
(4-7 years) can their performance be assessed. Thus the establishment of a reliable
micropropagation method for elite palms is required. Much research has been
devoted to this, but the recalcitrant character of the coconut palm in vitro has
limited progress. The induction of embryogenic callus is the first stage in such a
procedure and is the subject of this thesis.
Immature inflorescence has been much used as a source of explants, but the
rates of embryogenic callus production have been low. Values not exceeding 0.1%
with low reproducibility were obtained in this investigation and therefore
alternative sources of tissue have been explored.
Experiments with zygotic embryos showed that while mature embryos were
unsatisfactory for the culture of embryogenic callus, immature zygotic embryos
yielded callus in considerable amounts. Isolation of plumular tissue from mature
zygotic embryos gave embryogenic callus in around 80% of explants. This success
level exceeded other systems reported to date. Development of clonal plantlets
from plumular callus further indicated the significance of this as a useful tissue for
further research.
The synthetic auxin 2,4-D is normally used for the initiation of callus, but
other synthetic auxins with related chemical structures were also examined. The
highest yields of embryogenic callus (85 %) were obtained from plumules incubated
with picloram at 6 x 10"* M in media containing activated charcoal (AC). Levels
up to 2 X 10^ M picloram were also tolerated.
The effect of AC in reducing the availability of regulators in media has been
examined, using radio-labelled fluroxypyr acid, clopyralid and 2,4-D. Traces of
suspended AC in media held a significant proportion of the auxin in solution. The
release of adsorbed auxins from AC in culture media was achieved by the addition
of certain organic acids.
The monoclonal antibody ICS which hybridised with a 50 Kda protein in early
embryogenic cultures of various monocotyledonous species was found to hybridise
to a 50 Kda protein in coconut. Whether the presence of this protein is related to
the embryogenicity of coconut cultures remains to be determined.
develop axillary shoots and must therefore be propagated from seed. As it is a
heterozygous outbreeder, seedlings are variable and only after a long juvenile stage
(4-7 years) can their performance be assessed. Thus the establishment of a reliable
micropropagation method for elite palms is required. Much research has been
devoted to this, but the recalcitrant character of the coconut palm in vitro has
limited progress. The induction of embryogenic callus is the first stage in such a
procedure and is the subject of this thesis.
Immature inflorescence has been much used as a source of explants, but the
rates of embryogenic callus production have been low. Values not exceeding 0.1%
with low reproducibility were obtained in this investigation and therefore
alternative sources of tissue have been explored.
Experiments with zygotic embryos showed that while mature embryos were
unsatisfactory for the culture of embryogenic callus, immature zygotic embryos
yielded callus in considerable amounts. Isolation of plumular tissue from mature
zygotic embryos gave embryogenic callus in around 80% of explants. This success
level exceeded other systems reported to date. Development of clonal plantlets
from plumular callus further indicated the significance of this as a useful tissue for
further research.
The synthetic auxin 2,4-D is normally used for the initiation of callus, but
other synthetic auxins with related chemical structures were also examined. The
highest yields of embryogenic callus (85 %) were obtained from plumules incubated
with picloram at 6 x 10"* M in media containing activated charcoal (AC). Levels
up to 2 X 10^ M picloram were also tolerated.
The effect of AC in reducing the availability of regulators in media has been
examined, using radio-labelled fluroxypyr acid, clopyralid and 2,4-D. Traces of
suspended AC in media held a significant proportion of the auxin in solution. The
release of adsorbed auxins from AC in culture media was achieved by the addition
of certain organic acids.
The monoclonal antibody ICS which hybridised with a 50 Kda protein in early
embryogenic cultures of various monocotyledonous species was found to hybridise
to a 50 Kda protein in coconut. Whether the presence of this protein is related to
the embryogenicity of coconut cultures remains to be determined.
Version
Open Access
Date Issued
1995-01
Date Awarded
1995
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Blake, Jennet
Taylor, Herbert
Sponsor
European Community
Publisher Department
Agriculture, Horticulture and the Environment
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)
Author Permission
Permission granted