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dc.contributor.authorMurray, Katherine Jane Hope
dc.date.accessioned2020-08-19T21:53:43Z
dc.date.available2020-08-19T21:53:43Z
dc.date.issued2019
dc.identifier.urihttp://hdl.handle.net/10179/15561
dc.description.abstractThe 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.en_US
dc.language.isoenen_US
dc.publisherMassey Universityen_US
dc.rightsThe Authoren_US
dc.subjectOrchidsen_US
dc.subjectGenome mappingen_US
dc.subjectEvolutionen_US
dc.subjectNew Zealanden_US
dc.subjectChloroplastsen_US
dc.titleChloroplast 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 Zealanden_US
dc.typeThesisen_US
thesis.degree.disciplinePlant Biologyen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science (MSc)en_US
dc.subject.anzsrc310803 Plant cell and molecular biologyen


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