Mr Albert investigated the genetic mechanisms controlling complex floral and vegetative pigmentation patterns in Petunia. He discovered two new MYB transcription factors that control the timing and spatial location of anthocyanin pigment production in flowers and leaves, giving rise to specific colour patterns. He showed that complex pigmentation patterns are formed by tightly controlling the expression of genes required to synthesise anthocyanin pigments and involves proteins that both activate genes and repress them from being expressed. The interactions between distinct classes of transcription factors form an intricate network and hierarchy, allowing fine control of gene expression and strict control of pigment production. These findings will aid in the development of ornamental plants with new pigmentation patterns and also this research serves as a model for how plants control the expression of genes to produce health-promoting plant compounds.

Mr Albert investigated the genetic mechanisms controlling complex floral and vegetative pigmentation patterns in Petunia. He discovered two new MYB transcription factors that control the timing and spatial location of anthocyanin pigment production in flowers and leaves, giving rise to specific colour patterns. He showed that complex pigmentation patterns are formed by tightly controlling the expression of genes required to synthesise anthocyanin pigments and involves proteins that both activate genes and repress them from being expressed. The interactions between distinct classes of transcription factors form an intricate network and hierarchy, allowing fine control of gene expression and strict control of pigment production. These findings will aid in the development of ornamental plants with new pigmentation patterns and also this research serves as a model for how plants control the expression of genes to produce health-promoting plant compounds.

Mr Albert investigated the genetic mechanisms controlling complex floral and vegetative pigmentation patterns in Petunia. He discovered two new MYB transcription factors that control the timing and spatial location of anthocyanin pigment production in flowers and leaves, giving rise to specific colour patterns. He showed that complex pigmentation patterns are formed by tightly controlling the expression of genes required to synthesise anthocyanin pigments and involves proteins that both activate genes and repress them from being expressed. The interactions between distinct classes of transcription factors form an intricate network and hierarchy, allowing fine control of gene expression and strict control of pigment production. These findings will aid in the development of ornamental plants with new pigmentation patterns and also this research serves as a model for how plants control the expression of genes to produce health-promoting plant compounds.

This research investigated the rhizobia that are associated with New Zealand legume plants. Rhizobia are a diverse group of bacteria that live in symbiosis with legumes in root nodules. Rhizobia fix Nitrogen from the atmosphere and provide this nutrient to the plant. The objectives of this research were to: 1) Determine the identity of the rhizobial species nodulating the native legumes of New Zealand: Sophora (kowhai), Carmichaelia (NZ broom), and Clianthus (kakabeak); and the identity and origin of rhizobial species nodulating invasive exotic legumes in New Zealand: Ulex (gorse), Cytisus (broom), and Acacia (wattles). 2) Determine the specificity and nitrogen fixing capacity of both groups of rhizobia. 3) Investigate the possible exchange of transmissible symbiotic genetic elements. A polyphasic strategy was used to determine the identity of bacterial isolates. The 16S rRNA, atpD, recA, and glnII genes were PCR amplified and sequenced, then analysed by maximum likelihood and Bayesian methods. Phenotypic characters were also assessed by use of the Biolog and FAME techniques. Nodulation and fixation ability was assessed by inoculating legume seedlings with rhizobial strains, then determining nitrogenase activity after ten weeks by gas chromatography, and examining roots for nodules. A gene involved in symbiosis, nodA, was sequenced from rhizobial strains to determine if transmission between strains had occurred. The results of the experiments showed that the native legumes were predominately nodulated by diverse Mesorhizobium spp. that contain three different nodA genotypes (two of which are novel) that have transferred between rhizobial strains. The Mesorhizobium spp. showed little nodulation specificity and could nodulate an exotic legume Astragalus (milk vetch), but not the invasive weed legumes. Rhizobium leguminosarum was also found to nodulate native legumes, albeit ineffectively. The exotic invasive woody legumes of this study were nodulated by diverse Bradyrhizobium spp. that had nodA genotypes typical of Australian and European species. The origins of these bacteria can not be categorically determined. However the evidence is presented to suggest that nodulating Mesorhizobium spp. arrived with the ancestors of the native legumes, while Bradyrhizobium spp. nodulating Ulex and Cytisus arrived recently from Europe. Bradyrhizobium spp. nodulating Acacia may be recently introduced, possibly from Australia, although further work is required to confirm these hypotheses. / This study was supported by a grant from the Marsden Fund of the Royal Society of New Zealand, under contract 97-LAN-LFS-002, and a grant from the Non-Specific Output Fund of Landcare Research.

The analysis of presence/absence data of plant species by regression analysis is the subject of this thesis. A nonparametric approach is emphasized, and methods which take into account correlations between species are also considered. In particular, generalized additive models (GAMs) are used, and these are applied to species’ responses to greenhouse scenarios and to examine multispecies interactions. Parametric models are used to estimate optimal conditions for the presence of species and to test several niche theory hypotheses. An extension of GAMs called vector GAMs is proposed, and they provide a means for proposing nonparametric versions of the following models: multivariate regression, the proportional and nonproportional odds model, the multiple logistic regression model, and bivariate binary regression models such as bivariate probit model and the bivariate logistic model. Some theoretical properties of vector GAMs are deduced from those pertaining to ordinary GAMs, and its relationship with the generalized estimating equations (GEE) approach elucidated. / Whole document restricted, but available by request, use the feedback form to request access.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / This work constitutes a detailed study of the spores, of the ferns and fern allies, both native and adventive, which grow in New Zealand, from the Kermadec Islands in the North, to the Chatham Islands in the East and the Subantarctic Islands in the South. Twenty live families with sixty five genera, two hundred and eleven species (of which c.20 are introduced) and three subspecies are included. Seven species are heterosporous the remainder are homosporous. Trilete spores are found in c.104 species representing c.30 genera. Perine is present in most taxa (with the exception of Gleichenia) and ranges from the large and sac-like form as seen in Cyathea smithii, to the thin and reduced form seen in Adiantum. Monolete spores are found in c.109 species representing c.37 genera (two genera are included twice, Isoetes which has trilete megaspores and monolete microspores and Lindsaea which has both monolete and trilete species). Perine is present in most taxa (except Sticherus spp.) and ranges from a fine deposit as seen in the Psilotaceae, to an enlarged form, heavily winged, as seen in the Aspleniaceae. Sculpture in all taxa (with the exception of the Lycopodiaceae and some members of the Ophioglossaceae, which may have ornamentation distributed distally), is present on both distal and proximal faces. One adventive taxon Equisetum arvense L. has an unusual circular laesura and elaborate elaters. Light micrographs of acetolysed and fresh spores along with scanning electron micrographs, are included for each taxon. Keys presented, are based on gross spore morphology and are applicable to fresh and acetolysed material. Descriptions include a list of synonymous species, details of spore shape, laesura/ae details, perine/exine sculpture and thickness (where sections allow), size (measured from n=50 spores per population), for samples treated with cotton blue (lactophenol aniline blue formula), mounted in glycerine jelly and acetolysed samples, mounted in silicone oil. Percentage size differences for acetolysed material mounted in glycerine jelly are also noted, along with previous spore dimensions recorded in the literature. Descriptions also contain chromosome number, where known, a list of previously recorded descriptions, a brief indication of geographic location and a list of vouchers for each sample. Experiments on the size and morphology of fern spores in reaction to different preparation techniques are discussed. Fresh spores of seven species, four trilete (Adiantum fulvum, Cyathea smithii, Hymenophyllum flabellatum and Lycopodium volubile) and three monolete (Blechnum chambersii, Paesia scaberula and Tmesipteris elongata), were assessed wth regard to the effect of three standard pretreatments (lactophenol aniline blue, 10% KOH, acetolysis) and two mounting media (glycerine jelly and silicone oil). Changes in morphology and size of the various wall layers were noted in comparison to spores observed fresh in water. Results indicate that variation includes shrinkage e.g. silicone oil and expansion of both exine and perine in glycerine jelly. Both effects are modified by previous treatments.

Pterocladia lucida (R. Br.) J. Ag. is the prinipal raw material for agar production in New Zealand. Since collection commenced in 1943 the annual harvest has never stabilised and over recent years there has been a general decline, which has inhibited expansion of the indigenous industry. Field and laboratory studies have been made in order to obtain information on the biology of P. lucida. Form variability is considered in detail and a relationship between external morphology and wave exposure of the habitat is proposed. The culture of P. lucida from spores in a running seawater system is described in detail. Results on carpospore and tetraspore germination, and sporeling growth under light and temperature regimes are presented. Germination of both spore types was inhibited at 10°C while at higher temperatures germination was greatest under 4 klux. Spore germination and sporeling development in culture is described. Only sterile prostrate thalli possessing rhizoidal haptera were obtained and a hypothesis relating the appearance of surface haptera to the direction of irradiation is proposed. The development of an outdoor wave tank for culturing is described and the growth rate and development of sporelings is discussed with reference to water movement. Sporelings were maintained in culture for up to 22 months. Cultured sporelings have also been transplanted into different habitats. Creeping axes established from carpospores produced erect fronds, which produced tetraspores after seven to ten months in situ. This confirmed part of a Polysiphonia-type life history for the first time in a Gelidioid species. Axis elongation rate in situ was estimated to be less than 10cm year-1 at Leigh. It was concluded that the collection of attached weed could not be sustained annually, but controlled harvesting in specific areas every two years is advocated. Seasonal variation in agar yield and gel strength from wave exposed and sheltered populations of P. lucida was studied. Agar levels varied throughout the year, being greatest in spring and summer, while gel strengths showed a similar trend. The feasibility of utilising indigenous Gracilaria secundata Harvey forma pseudoflagellifera May has been studied. The yield and gel properties of agar were determined from different alkali pretreatments. There was a marked increase in gel strength when weed was pretreated in alkali, the maximum gel strength being obtained from a weed treatment of 3 percent NaOH for three hours at 80°C. The gel properties of agar from G. secundata f. pseudoflagellifera are compared with agar from other sources. The agar was suitable for commercial use, but exhibited a greater resilience than that from Pterocladia lucida. The vegetative regeneration of G. secundata f. pseudoflagellifera in the Manukau Harbour has been studied and an experimental harvest of 0.68t is described. During spring 100 percent regeneration from hand cleared and raked areas occurred after eight to thirteen weeks. Based on regeneration results, mechanical harvesting four times a year of Gracilaria mats in the Manukau Harbour is advocated. The predicted sustainable yield is 1084-1304t year-1. The extraction and gel properties of agar from Melanthalia abscissa (Turn.) Hook. et Harv. are reported for the-first time, but the commercial collection of this species is not advocated.

The role of, and response to, disturbance, in the dynamics of the mountain beech forest at western Mt Ruapehu, was examined, using palynology, dendrochronology, and vegetation survey. The pollen record indicates that, two thousand years ago, the west Ruapehu forest was dominated by Nothofagus solandri. About 1800 years B.P., the eruption of Lake Taupo devastated the forest. Though Halocarpus spp. and Phyllocladus asplenifolius were important early colonizers, Nothofagus solandri re-established itself close to its present limits after the eruption. Fire, from about 650 years ago onwards, did not affect the beech forest, but did affect the coniferous vegetation on the ring plain near the mountain. The age structure of the forest shows that there was a large disturbance event shortly before 1740. A dieback occurring about 1969 appears to have been the largest episode of mortality since 1740, larger than the dieback episode described by Cockayne at the beginning of this century. Dieback occurred as a short peak-period of Nothofagus solandri death about 1969. It was the large trees of the mature cohort which tended to be killed by dieback rather than the smaller individuals. Tree-ring analysis, showed that narrow tree-rings occurred in beech in the 1960's. Extreme rainfall years in the early 1960's may have put the beech trees under stress, making them susceptible to dieback. The drought in 1969 may have precipitated extensive mortality. The characteristics of N. solandri rings from Ruapehu are similar to ring characteristics of that species from South Island studies. The 1982 cyclone had a noticeable impact on the forest, affecting some areas severely. However, the impact was relatively minor compared to the influence of dieback. The mean density of trees >= 10cm dbh was 520 stems/ha., of which 220 stems/ha. were Nothofagus solandri. The mean basal area was 22m2 /ha., of which 11m2 /ha. was N. solandri. The basal area is very low compared to that in other N.Z. forests. N. solandri, Griselinia littoralis, Phyllocladus asplenifolius, Podocarpus hallii, and Libocedrus bidwillii, made up 35, 22, 16, 9, and 8 percent, respectively, of the total density. Basal area, density, and species composition varied as much within sites, as between them. The shrub layer formed a large part of the vegetation at west Ruapehu. Coprosma species were particularly abundant. There is sufficient regeneration to indicate that a new cohort of N. solandri is becoming established in most areas. Some areas will probably remain in shrubland for many decades. The result of dieback and windthrow has been to virtually eliminate the canopy of large old beech trees, and to increase the heterogeneity of stand structure. N. solandri seedling densities are not as high as those found in many South Island beech forests. Nothofagus solandri is growing faster than are most of the co-existing tree species, and it appears likely that it will continue as the dominant tree species. Implications for forest management are discussed.

Mr Albert investigated the genetic mechanisms controlling complex floral and vegetative pigmentation patterns in Petunia. He discovered two new MYB transcription factors that control the timing and spatial location of anthocyanin pigment production in flowers and leaves, giving rise to specific colour patterns. He showed that complex pigmentation patterns are formed by tightly controlling the expression of genes required to synthesise anthocyanin pigments and involves proteins that both activate genes and repress them from being expressed. The interactions between distinct classes of transcription factors form an intricate network and hierarchy, allowing fine control of gene expression and strict control of pigment production. These findings will aid in the development of ornamental plants with new pigmentation patterns and also this research serves as a model for how plants control the expression of genes to produce health-promoting plant compounds.

Pterocladia lucida (R. Br.) J. Ag. is the prinipal raw material for agar production in New Zealand. Since collection commenced in 1943 the annual harvest has never stabilised and over recent years there has been a general decline, which has inhibited expansion of the indigenous industry. Field and laboratory studies have been made in order to obtain information on the biology of P. lucida. Form variability is considered in detail and a relationship between external morphology and wave exposure of the habitat is proposed. The culture of P. lucida from spores in a running seawater system is described in detail. Results on carpospore and tetraspore germination, and sporeling growth under light and temperature regimes are presented. Germination of both spore types was inhibited at 10°C while at higher temperatures germination was greatest under 4 klux. Spore germination and sporeling development in culture is described. Only sterile prostrate thalli possessing rhizoidal haptera were obtained and a hypothesis relating the appearance of surface haptera to the direction of irradiation is proposed. The development of an outdoor wave tank for culturing is described and the growth rate and development of sporelings is discussed with reference to water movement. Sporelings were maintained in culture for up to 22 months. Cultured sporelings have also been transplanted into different habitats. Creeping axes established from carpospores produced erect fronds, which produced tetraspores after seven to ten months in situ. This confirmed part of a Polysiphonia-type life history for the first time in a Gelidioid species. Axis elongation rate in situ was estimated to be less than 10cm year-1 at Leigh. It was concluded that the collection of attached weed could not be sustained annually, but controlled harvesting in specific areas every two years is advocated. Seasonal variation in agar yield and gel strength from wave exposed and sheltered populations of P. lucida was studied. Agar levels varied throughout the year, being greatest in spring and summer, while gel strengths showed a similar trend. The feasibility of utilising indigenous Gracilaria secundata Harvey forma pseudoflagellifera May has been studied. The yield and gel properties of agar were determined from different alkali pretreatments. There was a marked increase in gel strength when weed was pretreated in alkali, the maximum gel strength being obtained from a weed treatment of 3 percent NaOH for three hours at 80°C. The gel properties of agar from G. secundata f. pseudoflagellifera are compared with agar from other sources. The agar was suitable for commercial use, but exhibited a greater resilience than that from Pterocladia lucida. The vegetative regeneration of G. secundata f. pseudoflagellifera in the Manukau Harbour has been studied and an experimental harvest of 0.68t is described. During spring 100 percent regeneration from hand cleared and raked areas occurred after eight to thirteen weeks. Based on regeneration results, mechanical harvesting four times a year of Gracilaria mats in the Manukau Harbour is advocated. The predicted sustainable yield is 1084-1304t year-1. The extraction and gel properties of agar from Melanthalia abscissa (Turn.) Hook. et Harv. are reported for the-first time, but the commercial collection of this species is not advocated.