Blue-flowered Conospermum are endemic to Western Australia, and show great potential as cut flowers. Propagation from cuttings or seed proved difficult, and root initiation in vitro is problematic. This thesis examines the floral biology of the species and the possibility of using somatic embryogenesis to overcome propagation problems. A survey of explant tissue types for C. eatoniae and C. caeruleum was carried out to identify tissue that could be induced into embryogenic pathways. Vegetative, semi-floral and floral buds were initiated into culture from February to June, but were found unsuitable for embryogenesis, producing shoots, callus or dying in culture. Leaves from in vitro leaf cultures formed callus in the presence of 2,4-D and BAP, but were unable to differentiate into embryos in the presence of a variety of growth regulator combinations and concentrations. Immature zygotes died in culture. Direct embryogenesis and/or embryogenic callus was observed on mature zygotes of the species C. caeruleum, C. spectabile, C. dorrienii and C. brownii, and somatic embryos were maintained in culture for up to 18 months for C. caeruleum. Maturation and germination of somatic embryos proved difficult; treatments of cold, ABA, desiccation or mannitol did not induce maturation. It appears that developmental pathways in Conospermum are well defined and are difficult to alter in vitro. It was concluded that somatic embryogenesis has limited commercial potential in these species. Conospermum species have an active pollination mechanism where the style is held in a state of tension when the flower opens. When pressure is applied at the base of the style by an insect, the style flicks downwards, striking the insect pollinator and releasing pollen from the anther in a single dusty mass. However, the breeding systems of blue-flowered Conospermum have not previously been well explored. Flowers on a C. eatoniae inflorescence opened from the basal end upwards acropetally, with the terminal two or three buds never opening. Fruit and seed set occurred only from the basal one to three buds. Isolation of C. eatoniae and C. amoenum flowers showed they were unable to self-pollinate in the absence of insect pollinators. Experiments to determine the timing of the peak of stigmatic receptiveness were inconclusive. Pollen germinated and penetrated the stigma 0 ¡V 6 days after anther dehiscence. Pollen loads on the stigma did not relate to the number of pollen tubes observed down the style. Controlled pollinations of cultivated C. eatoniae at a field station using self and cross pollen, revealed compatibility with a range of pollen genotypes, as pollen tubes were observed extending down the style. However, late-acting incompatibility could not be ruled out as controlled crosses failed to set any seed as flowers were shed from the bush. DNA analysis of open pollinated C. eatoniae seed progeny from two plants from a field station and two plants in natural bushland revealed very different pollination habits. Plants from the field station showed no outcrossing, with progeny closely resembling the maternal parent, whereas plants from the wild population showed outcrossing with several different paternal parents. These results suggest self-pollinated seed can be reliably obtained in a plantation situation using stands of ramets of the same clone. Alternatively, assuming that the required insect pollinators are present in a cultivated stand, it should be possible to obtain cross pollinated seed by surrounding the maternal plant with the desired paternal parent. Unusual pollen behaviour was observed for many blue-flowered species, a white-flowered species of Conospermum, and close relative, Synaphea petiolaris. Up to three pollen tubes emerged from the triporate pollen in vitro, and at rates of up to 55 ƒÝms-1. This rate was maintained for only 2 s but is greater than 20 times faster than reported in the literature for any species, in vitro or in vivo. Pollen with multiple tubes was also observed on the stigma in vivo in C. amoenum flowers. Changing the osmotic pressure of the germination medium by altering sucrose concentration influenced the number of tubes to emerge from the pollen grain; generally the number of tubes decreased as sucrose increased. However, the rate of tube growth was unaffected. The addition of calcium channel blockers to the germination medium had no effect on Conospermum growth rate, nor did they eliminate pulses of tube growth. Observation of Conospermum pollen ultrastructure revealed similarities to Gramineae pollen. The tube cytoplasm was packed with vesicles filled with material of similar electron density to the cell wall. Few golgi were identified, and the apical end of the tube contained these vesicles, smaller secretory vesicles and mitochondria. This is atypical of the tip, which is normally free of large vesicles. Distinct zones in the cytoplasm were not identified, which is similar to Gramineae. Like the grasses, Conospermum appears to pre-manufacture cell wall material and store it in vesicles ready for rapid germination and extension. A biological function of multiple pollen tube emergence with such rapid growth was not elucidated. This research has shown Conospermum to be a complex and very interesting genus. Further investigation into the remarkable growth of multiple pollen tubes would enhance our knowledge of the biological processes involved in tube growth and the process of fast wall formation. The potential benefits to the cut flower industry of commercialising some of these species warrants further effort to find an efficient method of propagation. Introduction into horticulture may be the only means by which these threatened species will survive.

The period between pollination and fertilization, or the progamic phase, is a critical life history stage in seed plants and innovations in this life history stage are hypothesized to have played an important role in the diversification of flowering plants. Over the course of this dissertation research, I investigated programic phase development in Nymphaeales (water lilies), an ancient angiosperm lineage that diverged from the basalmost or next most basal node of the angiosperm phylogenetic tree and that is represented in the oldest angiosperm fossil record. I used field experiments and microscopy to document pollination biology, breeding system, and reproductive developmental traits in two families of Nymphaeales: Cabombaceae (Brasenia, Cabomba) and Hydatellaceae (Trithuria). Nymphaeales exhibits considerable variation in reproductive traits and true carpel closure, wind-pollination, and a primarily selfing breeding system have arisen independently in the lineage. Pollen tube pathway length, timing of stigma receptivity, and pollen tube growth rates are conspicuous traits that have undergone considerable modification in concert with shifts in pollination biology and breeding system. Post-pollination developmental processes in Nymphaeales appear to experience selective pressures similar to those experienced by more derived angiosperms and to evolve in similar ways. Nymphaeales also exhibits traits, such as accelerated pollen tube growth, callosic pollen tube walls, and the formation of callose plugs, that are almost certainly plesiomorphic in angiosperms and may have facilitated modification of carpel structure and progamic phase ontogenies. The finding that pollen tube traits that underlie developmental flexibility were already in place before the divergence of Nymphaeales supports the hypothesis that innovations in male gametophyte development were instrumental in facilitating early angiosperm diversification.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(農学) / 甲第19043号 / 農博第2121号 / 新制||農||1032 / 31994 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 縄田 栄治, 教授 田中 千尋, 教授 北島 宣 / 学位規則第4条第1項該当

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19043号 / 農博第2121号 / 新制||農||1032(附属図書館) / 学位論文||H27||N4925(農学部図書室) / 31994 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 縄田 栄治, 教授 田中 千尋, 教授 北島 宣 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Invasive plants can alter pollination dynamics in invaded communities by disrupting patterns of pollinator visitation, pollen transfer dynamics (conspecific [CP] and heterospecific [HP]), and reproductive success. The direction of invasive effects (competitive, neutral, and facilitative) may be partially determined by spatial scale and species’ floral traits. Here, we investigated pollinator visitation, CP and HP receipt, and pollen tube growth for species in a C. arvense present community and non-present community at two scales. At the community-level, the effect of C. arvense on pollinator visitation varied among species. Floral symmetry seemed to explain this variation. At the floral neighborhood-level, we found competitive effects for pollinator visits and mixed effects on CP deposition. The overall structure of plant-plant HP deposition networks was slightly altered. We observed lower average centrality across shared species in the C. arvense present community suggesting C. arvense had subverted their roles as pollen donors.

Die vorliegende Arbeit prüft bei der gärtnerischen Modell-Kultur Cyclamen den Einfluss des Genotyps (interspezifische Hybriden) auf generative Merkmale sowie bei C. persicum `Melody´ den Einfluss von Kultivierungsmaßnahmen wie die Besiedelung der Wurzeln durch einen symbiontischen Pilz (Piriformospora indica) in Kombination mit einem differenzierten Phosphor-Angebot auf vegetative und generative Merkmale: (1) Pflanzendurchmesser, (2) Blühzeitpunkt und Blütenanzahl, (3) Anzahl Samenanlagen pro Fruchtknoten, (4) Vitalität von Pollen und Samenanlagen, (5) Mikrosporogenese, (6) Befruchtungsvorgang (Pollenschlauchwachstum, Anteil Fruchtknoten mit Pollenschläuchen, Anzahl Pollenschläuche im Griffel und Penetration der Pollenschläuche in die Micropyle), (7) abortierte Blüten nach der Bestäubung (8) Samenbildung und (9) Samenanzahl. / The present paper investigates Cyclamen as an horticultural model-culture. A main Focus is on the characteristics of the Cyclamen genotype, notably with interspecific hybrids. Further, Cyclamen persicum cv. served as a model to analyse effects on parameters of pollination, seed development and number of ovules per ovary, which are caused by a root colonization of the seed bearer with the symbiotic fungus Piriformospora indica (Piri) in combination with a differentiated phosphorus supply. In this regard, plant diameter, flowering time and flower number, the viability of pollen and ovules, the microsporogenesis, the growth of pollen tubes, the seed formation and the seed count were considered among important parameters of pollination and seed development.