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dc.contributor.authorAbernethy, Grant Andrew
dc.date.accessioned2012-11-12T20:30:29Z
dc.date.available2012-11-12T20:30:29Z
dc.date.issued1996
dc.identifier.urihttp://hdl.handle.net/10179/4017
dc.description.abstractResponses to water-deficit stress by a xerophytic tussock native to sub-alpine grasslands of New Zealand have been investigated. Festuca novae-zealandiae possesses some structural adaptions such as curled laminae, limited stomatal distribution, and dense trichomes characteristic of dry-land adapted species. These features were compared with those of a mesophyte, F. arundinacea. In addition to structural adaptions, evidence that metabolic changes contribute to the drought tolerance of F. novae-zealandiae was sought. Plants of F. arundinacea and F. novae-zealandiae were grown in glasshouse pots and were subjected to water-deficit. Concentrations of the phytohormone ABA and the osmoprotectants proline and glycine-betaine increased in mature laminae of F. arundinacea as SWC declined to 8%. In F. novac-zealandiae, ABA concentration increased from 25-50 ng/gDW in two steps. At the first step (at 9-10% SWC), the increase was greatest in leaf bases (to 150 ng/gDW), and the second increase (at 6% SWC) was greatest in laminae (to 320 ng/gDW) and non-existent in leaf bases. In water-sufficient tillers, proline concentration was elevated in leaf bases (5-8 mg/ g DW) compared to laminae (2 mg/ g DW) and increased to 28 mg/ g DW in leaf bases, and to 14 mg/ g DW in laminae as SWC declined to 8-9%. Glycine-betaine concentration (40-100 µmol/ gDW) was unchanged by water-deficit stress. Leaf and tiller counts, and estimates of leaf tip scorching indicated that leaf death progressed with increasing water-deficit. Although leaf elongation declined, it did not cease until the last tillers had died. SDS-PAGE and Western analysis of soluble proteins using antisera to ubiquitin indicated that protein turnover increased in lamina, but not in leaf bases in response to water-deficit. It was concluded that in response to water-deficit stress, leaf bases of F. novae-zealandiae retained turgor and remained viable at the expense of existing leaf laminae, which died back. Southern analysis suggested that the F. novae-zealandiae genome contains sequence(s) with homology to group 2 LEA proteins. Western analysis using antisera raised against the dehydrin consensus sequence KIKEKLPG revealed several related proteins in seeds of F. novae-zealandiae, but these were not induced by water-deficit stress in leaves.en
dc.language.isoenen
dc.publisherMassey Universityen_US
dc.rightsThe Authoren_US
dc.subjectTussocken
dc.subjectFescue tussocken
dc.subjectHard tussocken
dc.subjectFestuca novae-zelandiae.en
dc.subjectDrought toleranceen
dc.titleResponse to water deficit stress in the native New Zealand tussock, Festuca novae-zealandiae : submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Department of Plant Biology and Biotechnology, Massey University, Palmerston North, New Zealanden
dc.typeThesisen
thesis.degree.disciplinePlant Biologyen
thesis.degree.grantorMassey Universityen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophy (Ph.D.)en


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