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    Comparison of seed traits of tropical (Indonesia) and temperate (New Zealand) orchid species to support orchid seed conservation : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Horticultural and Agricultural Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2020) Diantina, Surya
    Most orchid species are endangered, and a basic understanding of their seed biology is required to support conservation efforts. In particular, more knowledge of orchid seed characteristics would be useful for both in situ and ex situ conservation. This comparative study used morphological and biochemical approaches to characterise and compare orchid seed qualitative and quantitative traits, to explore biochemical changes during natural seed ageing and to investigate different asymbiotic in vitro seed germination media and cryopreservation techniques for ex situ conservation. This study included six orchid species with different growth habits and distribution ranges (Dendrobium strebloceras, D. lineale, D. cunninghamii (epiphytic), Gastrodia cunnninghamii, Pterostylis banksii and Thelymitra nervosa (terrestrial)) from temperate New Zealand and tropical Indonesia. Morphometric analyses revealed similarities in the qualitative traits of seeds and capsules at the genus level (Dendrobium). However, high variability in micro-morphological seed characteristics were observed in the orchid species in this study which were unrelated to their taxonomy, biogeographical origin, or growth habit, suggesting different ecological adaptations possibly reflecting different modes of dispersal. An investigation of the seed fatty acids showed that linoleic, oleic and palmitic acids (polyunsaturated, monounsaturated and saturated fatty acids, respectively) were the most abundant fatty acids in the seeds of all species and that rapid degradation of unsaturated acids occurred during ageing. Three epiphytic Dendrobium species had similar lipid composition but Gastrodia cunnninghamii, Pterostylis banksii and Thelymitra nervosa (terrestrial species) were characterised by the absence of erucic and palmitoleic acid. Changes in the proportion of oleic and linolenic acid were strongly correlated with seed viability loss. The ageing pattern was species-specific with D. strebloceras being more vulnerable to lipid degradation. Epiphytic Dendrobium orchids had a less stringent media formulation requirement for seed growth than terrestrial orchids, and similarly, seeds of tropical species D. lineale and D. strebloceras germinated more easily than those of temperate species in this study. Cryopreservation with direct immersion of dry orchid seeds in liquid nitrogen is suggested as the most effective and efficient method for orchid seed conservation.
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    Chloroplast genome evolution in New Zealand mycoheterotrophic Orchidaceae : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Biology at Massey University, Manawatu, New Zealand
    (Massey University, 2019) Murray, Katherine Jane Hope
    The plastid genomes, or plastomes, of most photosynthetic land plants are highly similar. In contrast, those of non-photosynthetic, heterotrophic land plants are often reduced in both size and gene content. The apparent degradation of mycoheterotrophic plant plastomes has been attributed to a functionally-driven stepwise pattern of loss. However, the number of complete plastome sequences available for mycoheterotrophic plants is small and taxonomic coverage is biased. In this thesis, the plastomes of two mycoheterotrophic orchid species endemic to New Zealand, Corybas cryptanthus Hatch (Diurideae) and Danhatchia australis Garay & Christenson (Goodyerinae), as well as those of an albino and several photosynthetic representatives of Corybas are reported. Beyond increasing the number of mycoheterotrophic plastomes available for evaluating broad hypotheses about plastome evolution in non-photosynthetic plants, these data also provide insights into two little studied aspects of plastome evolution in mycoheterotrophs; intraspecific variation in the plastomes of mycoheterotrophs and the differences between mycoheterotrophs and their closest photosynthetic relatives. The plastomes of C. cryptanthus and D. australis differ in the extent to which they are degraded. Perhaps unexpectedly, the plastome of C. cryptanthus, which has close photosynthetic relatives and therefore is likely to have arisen more recently than the taxonomically isolated D. australis, is more reduced. Specifically, the plastomes of C. cryptanthus are approximately half the size and have half the gene content of the other Corybas sequenced whereas the plastome of D. australis is similar to those available for photosynthetic relatives. This contrast may reflect underlying differences between the two genera; the photosynthetic relatives of D. australis have plastomes containing NADH dehydrogenase (ndh) genes whereas those of photosynthetic Corybas have lost their ndh genes and their small single copy regions are highly reduced. These features may have predisposed the ancestor of C. cryptanthus to rapid genome degradation. Finally, observations on these results strongly suggest that plastome degradation follows, rather than precedes, the shift to mycoheterotrophy.
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    Pollination ecology of New Zealand orchids : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University
    (Massey University, 2002) Lehnebach, Carlos A
    The New Zealand orchid flora comprises twenty-five genera and at least 100 species occurring throughout the country. Although the number of endemic species is high (69%) only four genera are endemic to New Zealand. The main physical threats to orchid survival in New Zealand are habitat destruction, modification and fragmentation. The effect of the disruption of interactions with their pollinators has never been considered. This study concentrates on this mutualistic interaction, by assessing the breeding system, pollination syndromes and pollinator-dependence of four widespread terrestrial (Gastrodia cunninghamii, Thelymitra longifolia, Pterostylis alobula and P. patens) and four widespread epiphytic orchids (Earina autumnalis, E. aestivalis, E. mucronata and Winika cunninghamii) occurring in the southern portion of the North Island. In order to determine the breeding system and the presence of self-incompatibility, hand-pollination treatments were conducted in all eight orchid species during the flowering seasons of 2001 and 2002. Pollen grains and ovules numbers, pollen:ovule ratio and presence of floral scent glands were assessed. In those nectariferous species (E. autumnalis, E. aestivalis, E. mucronata and W. cunninghamii), the nectar standing crop was determined using the anthrone colorimetric assay for total carbohydrates. The activity of pollinator was observed both in the field and in captivity. Insects observed foraging in these orchids were identified and ranked according to their likely pollination effectiveness. Finally, measurements of pollination success and pollinia removal and deposition were used to assess whether fruit-set is pollen limited in these species and explore the effect contrasting rewarding strategies (nectar v/s deception) has on the pollination success of these orchids. Pollination treatments in three terrestrial (T. longifolia, P. alobula and P. patens) and two epiphytic (E. autumnalis and E. mucronata) orchids confirmed the absence of genetic incompatibility. Despite these five orchids being self-compatible, their reproduction relies on contrasting reproductive strategies. T. longifolia is predominantly self-pollinated, whereas Pterostylis and Earina species are incapable of autonomous selfing and completely dependent on pollinators. The epiphytic species E. aestivalis and W. cunninghamii are partially self-incompatible and also completely dependent on pollinators. Agamospermy is likely to occur in G. cunninghamii but not involved in seed-production in any of the remaining seven orchids. Both terrestrial and epiphytic species showed a positive reaction to neutral red except E. autumnalis. This indicated the presence of scent glands, mainly located around the column, lip and sepal tips. Pollen:ovule ratios calculated for these species ranged from 20:1 in E. mucronata and E. aestivalis to 320: 1 in P. alobula. Of the four terrestrial orchids studied, insect visitation was observed only in P. alobula. This orchid is pollinated by male fungus gnats of the genus Zygomyia (Diptera: Mycetophilidae). Pollination by sexual deception is likely to occur in species of this genus. Numerous insects were recorded visiting the nectariferous epiphytic orchids (3 orders, 13 families). Insects considered as "probable pollinator" were Eristalis tenax (Diptera: Syrphidae) for Earina autumnalis, Dilophus nigrostigmus (Diptera: Bibionidae) for E. mucronata, and Melangyna novaezealandiae (Diptera: Syrphidae), Calliphora quadrimaculata (Diptera: Calliphoridae), the Ichneumonid wasp Aucklandella sp. (Hymenoptera: Ichneumonidae), Hylaeus sp. (Hymenoptera: Colletidae) and an unidentified weevil (Coleoptera: Curculionidae) for E. aestivalis. In W. cunninghamii the species Apis mellifera and the native syrphid flies Helophilus antipodus and M. novaezealandiae were considered as "probable pollinators". Levels of natural fruit-set were similarly low in rewarding and non-rewarding species fluctuating from 4.3% (P. alobula) to 40% (P. patens). Fruiting in these orchids is pollen limited, as supplementary hand-pollinations increased fruit set above 40% in all species except P. patens. The degree of pollen limitation varied from 0.32 (P. patens) and 0.94 (P. alobula and E. mucronata). Pollen limitation in these orchids may be caused by the simplicity of their flowers, the poor efficiency of their pollinators in depositing pollinia and the use of species-specific pollination systems (e.g. Pterostylis). The survival capability and conservation requirements of these orchids are discussed in the light of the specific reproductive requirements revealed by this study.
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    The biogeography, ecology and endophyte mycorrhiza of the New Zealand Corybas alliance (Orchidaceae) : specifically, Nematoceras iridescens (Irwin et Molloy) Molloy, D.L.Jones & M.A.Clem. (species) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology at Massey University, Palmerston North, New Zealand
    (Massey University, 2012) Watkins, Roger L S
    No research on the fungal endophytes in the green New Zealand terrestrial orchids has been published. Identification of the endophyte resident in Nematoceras iridescens roots was accomplished by comparing hyphal septal ultra-structure and using TEM imaging of the hyphal septa, all of which indicated that the genus Tulasnella was involved. The Tulasnella species was identified using molecular techniques focused on sequencing of the ribosomal RNA locus on the ITS1–5.8S–ITS2 nuclear ribosomal gene. The endophytic fungi, resident in the host plant N. iridescens and the germinating seed of this species, were identified for the first time as strains of Tulasnella calospora. Scanning electron microscopy (SEM), light microscopy (LM) and Confocal Laser Scanning Microscopy (CLSM) was used to investigate spatial distribution of the endophyte hyphae within the plant. The SEM results identified four morphological types of hyphae: initiating, divaricating, intercellular and necrotised, or undergoing lysis. Peloton formation only occurred in specific areas of the root; mainly within the sub-epidermal and mid cortex cells. No hyphal involvement within the stele or the immediately adjacent cortex cells occurred. This thesis, based on meteorological information, proposes that the centre of origin of Nematoceras is likely to be Papua New Guinea, with on-going dispersal being direct or from Australia to New Zealand. Wind vectors and Nematoceras adaptations to seed dispersal, both local and long distance, were investigated and tend to support this hypothesis. Germination of all known orchid seed requires an obligate mycoheterotroph, generally a member of the Basidiomyceteae. For the first time, CLSM has imaged the fungal endophyte within the seed embryo and this was identified by molecular techniques and found to be a unique strain of T. calospora. Three methods of orchid seed germination were trialled: symbiotic, asymbiotic and field envelopes. After a 12-month period, only field envelopes produced germinating seeds of N. iridescens. In all other methods the seed failed to germinate. All Nematoceras spp. are solitary leafed and classified as moist mesophytes. Leaves were found to be hypostomatous. Being single leaved, protection is essential and a number of adaptations to counter herbivoury were found: raphide crystals, wax cuticle, winter maturity with summer–autumn aestivation all provide an antiherbivoury component. The relationship between the genera of Nematoceras plus Singularybas and the associated species, of the far more ancient Hepatophyte order of Metzgeriales, were investigated. The genus Aneura contains peloton like vesicles of various strains of T. calospora. The majority of the Hepatophytes have a parallel geographic-ecological requirement. The T. calospora mycorrhiza of the Metzgeriale genus Aneura was found to have a close association with the Corybas alliance observed.