Reproductive biology and ex situ conservation of the genus Restrepia (Orchidaeae)

2.50
Hdl Handle:
http://hdl.handle.net/2436/311706
Title:
Reproductive biology and ex situ conservation of the genus Restrepia (Orchidaeae)
Authors:
Millner, Helen Jean
Abstract:
The genus Restrepia is well known to orchid enthusiasts but its micromorphology has not been described, and its pollination and breeding systems have not been investigated. The aim of this investigation was, therefore, to add to existing knowledge so that the resultant data could be used to facilitate ex situ conservation initiatives. A detailed electron microscopy study (SEM) of the floral organs was performed. This confirmed the structure of the dorsal sepal and lateral petal osmophores, their secretory nature together with that of the synsepal and the labellum. It was postulated how, by manipulating different labellar surface textures, the flower might use these ‘tactile guides’ to steer the insect (fly) through the flower. The cirrhi were postulated to help by destabilising the pollinator in flight, trapping it and bringing about pollination. The papillate structure of the calli was established and their optical properties investigated. Media comparison investigations established that Western medium supported the highest germination rates and, with the addition of banana supplement, the highest rates for seedling growth and development. This represented the first protocol for axenic germination of Restrepia in the literature (Millner et al., 2008) and provided a tested methodology for investigating breeding systems and producing Restrepia plant material for both scientific and horticultural purposes. Self-pollinations were found to produce fewer embryos compared to cross-pollinations. The operation of self-incompatibility (SI) was confirmed by the study of pollen tube growth which further confirmed the time interval between pollination and fertilisation. A time line from pollination/fertilisation to flowering was established. The type of SI in operation was best explained by gametophytic incompatibility. This demonstrated that it was possible to raise Restrepia hybrids and species from seed, by performing intraspecific crosses so helping to preserve them for posterity and relieve pressure on wild populations. Narrow endemic Restrepia species face combined threats from habitat loss, habitat degradation and problems of viable seed production due to the effects of SI and inbreeding depression (ID). Recently developed online resources, such as GeoCAT, were used to perform a Red List assessment in order to identify the degree of threat individual species faced, both globally and nationally. All species were classified as facing substantial levels of threat; although this was lessened for populations in protected habitats. Conservation is needed for cultivated collections as well as these wild populations by keeping alive existing knowledge and expertise in growing these species.
Advisors:
Baldwin, T.C. & McCrea, A.R.
Publisher:
University of Wolverhampton
Issue Date:
2013
URI:
http://hdl.handle.net/2436/311706
Type:
Thesis or dissertation
Language:
en
Description:
A thesis presented for the degree of Doctor of Philosophy
Appears in Collections:
E-Theses

Full metadata record

DC FieldValue Language
dc.contributor.advisorBaldwin, T.C. & McCrea, A.R.en_GB
dc.contributor.authorMillner, Helen Jeanen_GB
dc.date.accessioned2014-01-22T14:58:49Z-
dc.date.available2014-01-22T14:58:49Z-
dc.date.issued2013-
dc.identifier.urihttp://hdl.handle.net/2436/311706-
dc.descriptionA thesis presented for the degree of Doctor of Philosophyen_GB
dc.description.abstractThe genus Restrepia is well known to orchid enthusiasts but its micromorphology has not been described, and its pollination and breeding systems have not been investigated. The aim of this investigation was, therefore, to add to existing knowledge so that the resultant data could be used to facilitate ex situ conservation initiatives. A detailed electron microscopy study (SEM) of the floral organs was performed. This confirmed the structure of the dorsal sepal and lateral petal osmophores, their secretory nature together with that of the synsepal and the labellum. It was postulated how, by manipulating different labellar surface textures, the flower might use these ‘tactile guides’ to steer the insect (fly) through the flower. The cirrhi were postulated to help by destabilising the pollinator in flight, trapping it and bringing about pollination. The papillate structure of the calli was established and their optical properties investigated. Media comparison investigations established that Western medium supported the highest germination rates and, with the addition of banana supplement, the highest rates for seedling growth and development. This represented the first protocol for axenic germination of Restrepia in the literature (Millner et al., 2008) and provided a tested methodology for investigating breeding systems and producing Restrepia plant material for both scientific and horticultural purposes. Self-pollinations were found to produce fewer embryos compared to cross-pollinations. The operation of self-incompatibility (SI) was confirmed by the study of pollen tube growth which further confirmed the time interval between pollination and fertilisation. A time line from pollination/fertilisation to flowering was established. The type of SI in operation was best explained by gametophytic incompatibility. This demonstrated that it was possible to raise Restrepia hybrids and species from seed, by performing intraspecific crosses so helping to preserve them for posterity and relieve pressure on wild populations. Narrow endemic Restrepia species face combined threats from habitat loss, habitat degradation and problems of viable seed production due to the effects of SI and inbreeding depression (ID). Recently developed online resources, such as GeoCAT, were used to perform a Red List assessment in order to identify the degree of threat individual species faced, both globally and nationally. All species were classified as facing substantial levels of threat; although this was lessened for populations in protected habitats. Conservation is needed for cultivated collections as well as these wild populations by keeping alive existing knowledge and expertise in growing these species.en_GB
dc.language.isoenen
dc.publisherUniversity of Wolverhamptonen
dc.subjectOrchidaceaeen_GB
dc.subjectRestrepiaen_GB
dc.subjectex situ conservationen_GB
dc.subjectself-incompatibility (SI)en_GB
dc.subjectRed List statusen_GB
dc.subjectfly pollinationen_GB
dc.subjecttissue cultureen_GB
dc.subjectscanning electron microscopyen_GB
dc.subjectosmophoresen_GB
dc.subjectcallien_GB
dc.titleReproductive biology and ex situ conservation of the genus Restrepia (Orchidaeae)en_GB
dc.typeThesis or dissertationen
dc.type.qualificationnamePhDen
dc.type.qualificationlevelDoctoralen
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