This thesis is concerned with the formation and structure of silicified deposits in biology. The major system studied is silicified macrohairs from the lemma of the grass Phalaris canariensis L. The macrohairs consist of silica and polysaccharides. Chemical and structural studies on the mineral phase utilised electron microscopy (transmission (TEM), scanning (SEM) and ultra high resolution (HRTEM)), energy disoersive X-ray analysis (EDXA), solid state nuclear magnetic resonance ( ᷣ⁹ Si nmr), infrared spectroscopy, birefringence and nitrogen adsorption experiments. Results showed that the silica is chemically 'pure', hydrated, amorphous at a resolution of 1OÅ and a variety of structural morphologies were observed which are related to the maturity of the macrohair. Analytical studies at different times after emergence of the inflorescence utilising EDXA and scanning proton microprob eanalysis (SPM) showed that the inorganic elements Si, K, P, S and Cl are spatially organised within the macrohairs during silicification. It is proposed that the macrohairs are silicified under strict cellular control. The organic matrix in the mature macrohairs was investigated by acid hydrolysis and chromatography. The changing emphasis of polysaccharide synthesis in the macrohairs as mineralisation occurs was followed by in vivo radioactive labelling of inflorescences at different stages using ⁱ⁴C glucose and Harabinose. Analysis o fpolysaccharides synthesised involved acid hydrolysis and enzymic digestions (Amylase and Driselase), followed by paper and thin layer chromatography with scintillation counting of the products. Results showed that at the early stages of mineralisation, arabinoxylans and cellulose are the major polymers synthesised but as the macrohair matures, largely non-cellulosic glucans (as yet unidentified) are synthesised. It is proposed that the change in emphasis of polysaccharide synthesis during wall development is related to the size and ultrastructural arrangements of silica particles observed. The organic matrix was also observed to give additional order to the system, the resulting material being totally impervious. A second system, chosen for comparison, is mineralised teeth from the radula of the common limpet Patella vulgata. The mature teeth contain silica, iron oxide (goethite) and an organic matrix. Investigations on the silicified phase utilising electron microscopy revealed morphological structural variations. Analytical studies involving EDXA and SPM analysis showed that there are complex temporal and spatial variations in the inorganic composition (P, S, Ca, Fe, Si, Cu) in all regions of the teeth. It is proposed that these changes can be correlated with changes in composition of the organic matrix. A comparison is made of the silica from the two systems.

Le lac Saint-Pierre (LSP) est un écosystème d'une valeur écologique nationale et internationale. Cependant, il subit une dégradation due à la conversion des terres en cultures annuelles, principalement le maïs (*Zea mays* L.) et le soja (*Glycine max* [L.] Merr.). Cela a entraîné une diminution significative des populations de perchaudes (*Perca flavescens*), indicateurs clés de sa santé. Pour préserver le milieu, des bandes herbacées pérennes sont proposées, offrant une double protection contre l'érosion des sols et la pollution agricole tout en favorisant la biodiversité. L'alpiste roseau (*Phalaris arundinacea* L.), adapté aux conditions du littoral du LSP, peut créer des habitats de reproduction pour les poissons. Ce projet analyse les facteurs menant au succès d'implantation des bandes herbacées pérennes, dont l'alpiste roseau, dans le littoral du LSP. Un dispositif expérimental a été établi à l'été 2022 sur deux sites dans la plaine inondable du LSP. Il a permis d'évaluer divers facteurs comme les plantes-abris, les taux de semis d'alpiste et le travail du sol. Les résultats après deux années ont montré un effet négatif des plantes-abris sur l'établissement de l'alpiste. En leur absence, l'alpiste atteint des niveaux optimaux de recouvrement, de hauteur et de biomasse. Le taux de semis n'a pas affecté le recouvrement de l'alpiste, mais des différences ont été observées dans la croissance verticale et la répression des adventices. Le faux semis n'a pas limité la croissance des adventices. De plus, trois autres essais ont été réalisés, évaluant les mélanges herbacés, les traitements de paillis et l'implantation de l'alpiste par rhizomes. Les mélanges avec des plantes indigènes ont présenté des résultats mitigés, tandis que certains paillis ont limité la croissance des adventices. L'implantation de l'alpiste par rhizomes a échoué faute d'équipement adéquat. Cette étude souligne l'intérêt de considérer certains facteurs dans l'établissement des bandes herbacées pérennes en contexte de plaine inondable. / Lake Saint-Pierre (LSP) is an ecosystem of national and international ecological value. However, it is undergoing degradation due to land conversion to annual crops, mainly maize (*Zea mays* L.) and soybean (*Glycine max* [L.] Merr.). This has led to a significant decrease in populations of yellow perch (*Perca flavescens*), key indicators of its health. To preserve the environment, perennial herbaceous strips are proposed, providing dual protection against soil erosion and agricultural pollution while promoting biodiversity. Reed canarygrass (*Phalaris arundinacea* L.), suited to the conditions of the LSP shoreline, can create breeding habitats for fish. This project analyzes factors contributing to the success of perennial herbaceous strip establishment, including reed canarygrass, in the LSP shoreline. An experimental setup was established in the summer of 2022 at two sites in the LSP floodplain. It evaluated various factors such as companion plants, reed canarygrass seeding rates, and soil tillage methods. Results after two years showed a negative effect of companion plants on reed canarygrass establishment. In their absence, reed canarygrass reached optimal levels of coverage, height, and biomass. Seeding rates did not affect reed canarygrass coverage, but differences were observed in vertical growth and weed control. Stale seed bed method did not limit weed growth. Additionally, three other trials were conducted, evaluating herbaceous mixtures, mulching treatments, and rhizome implantation of reed canarygrass. Mixtures with native plants showed mixed results, while some mulches limited weed growth. Rhizome implantation failed due to inadequate equipment. This study underscores the interest of considering specific factors in establishing perennial herbaceous strips in floodplain contexts.

Self-incompatibility (SI) is an important genetic mechanism to prevent the inbreeding of flowering plants and also an excellent system for studying cell-cell recognition and signal transduction. During evolution, several SI systems have been evolved. A unique SI system widely spreads in the grasses. In the grasses, two unlinked, multi-allelic loci (S and Z) determine SI specificity. A putative self-incompatibility gene (Bm2) was previously cloned. In this study, the role of Bm2 in self-incompatibility was investigated first. The cDNA homologues of Bm2 were sequenced from two pollen-only mutants. The results indicated that Bm2 is not the one of SI genes in Phalaris, but represents a subclass of thioredoxin h. Thus a map-based cloning strategy was then adopted to clone the SI genes from Phalaris. Fine linkage maps of the S and Z regions were constructed. RFLP probes from wheat, barley, oat and rye were screened and the S locus was delimited to 0.26 cM and the Z locus to 1.0 cM from one side using specially designed segregating populations. The S locus was located to the sub-centromere region of triticeae chromosome group 1 and the Z locus to the middle of the long arm of group 2. Finally, barley and rice bacterial artificial chromosome (BAC) clones corresponding to the S and Z region were identified to analyse the chromosome structures and to seek candidate SI genes. The abundant repetitive sequences in the identified barley BAC clones limit their usefulness. Identification of Rice BAC clones orthologous to the S and Z regions open the gate to use rice genome information to clone SI genes from the grasses. A positive rice clone (139.9 kb) orthologous to the S region contained 19 predicted genes. Several of these genes might be involved in pollen tube germination and pollen-stigma interaction, which are the major parts of SI reaction. A positive clone (118.9 kb) orthologous to the Z region gave 16 predicted genes. The predicted genes on the outmost ends of these clones could be used to construct contigs to cover the S and Z regions and delimit the S and Z loci in the grasses. / Thesis (Ph.D.)--Department of Plant Science, 2001.

Self-incompatibility (SI) is an important genetic mechanism to prevent the inbreeding of flowering plants and also an excellent system for studying cell-cell recognition and signal transduction. During evolution, several SI systems have been evolved. A unique SI system widely spreads in the grasses. In the grasses, two unlinked, multi-allelic loci (S and Z) determine SI specificity. A putative self-incompatibility gene (Bm2) was previously cloned. In this study, the role of Bm2 in self-incompatibility was investigated first. The cDNA homologues of Bm2 were sequenced from two pollen-only mutants. The results indicated that Bm2 is not the one of SI genes in Phalaris, but represents a subclass of thioredoxin h. Thus a map-based cloning strategy was then adopted to clone the SI genes from Phalaris. Fine linkage maps of the S and Z regions were constructed. RFLP probes from wheat, barley, oat and rye were screened and the S locus was delimited to 0.26 cM and the Z locus to 1.0 cM from one side using specially designed segregating populations. The S locus was located to the sub-centromere region of triticeae chromosome group 1 and the Z locus to the middle of the long arm of group 2. Finally, barley and rice bacterial artificial chromosome (BAC) clones corresponding to the S and Z region were identified to analyse the chromosome structures and to seek candidate SI genes. The abundant repetitive sequences in the identified barley BAC clones limit their usefulness. Identification of Rice BAC clones orthologous to the S and Z regions open the gate to use rice genome information to clone SI genes from the grasses. A positive rice clone (139.9 kb) orthologous to the S region contained 19 predicted genes. Several of these genes might be involved in pollen tube germination and pollen-stigma interaction, which are the major parts of SI reaction. A positive clone (118.9 kb) orthologous to the Z region gave 16 predicted genes. The predicted genes on the outmost ends of these clones could be used to construct contigs to cover the S and Z regions and delimit the S and Z loci in the grasses. / Thesis (Ph.D.)--Department of Plant Science, 2001.

Canary grasses (Phalaris, Poaceae) include 21 species widely distributed throughout temperate and subtropical regions of the world with centers of diversity in the Mediterranean Basin and western North America. The genus contains annual/perennial, endemic/cosmopolitan, wild, and invasive species with basic numbers of x=6 (diploid) and x=7 (diploid/tetraploid/hexaploid). The latter display vastly greater speciation and geographic distribution. These attributes make Phalaris an ideal platform to study species diversification, dispersal, historic hybridization, polyploidy events, and chromosome evolution in the grasses. This body of research presents the first molecular phylogenetic and phylogeographic reconstruction of the genus based on the nuclear ITS and plastid trnT-F DNA regions allowing species relationships and the importance of polyploidy in speciation to be assessed. Divergence dates for the genus were determined using Bayesian methods (BEAST, version 1.6.2) and historic patterns of dispersal were analyzed with RASP (version 2.1b). Self-incompatibility and the feasibility of hybridization between major groups within the genus were studied with a series of greenhouse experiments. Acetocarmine and fluorescent staining techniques were used to study the morphology of the chromosomes in a phylogenetic context and the nuclear DNA content (C values) was quantified using flow cytometry. Four major clades were revealed in the genus with cytological and geographic affinities leading to the establishment of two subgenera and four sections in the first comprehensive infrageneric treatment of Phalaris. Divergence dating revealed a Miocene emergence (20.6-8.4 MYA) for the genus which is concurrent with studies of other genera in the Aveneae tribe. The hypothesis stating that Phalaris originated in the Mediterranean Basin and dispersed to the New World via a western route leading to a secondary center of diversification in western North America was supported by phylogeographic and cytological analyses. An empirical study comparing the weight, length, and width of the florets by morphological type and cytotype revealed significant differences that support a dispersal advantage among the New World and Arundinacea species. The x=6 species displayed greater intraspecific C value variation, higher DNA content per haploid chromosome set, and a distinct karyotype compared with the x=7 species indicating a complex history of chromosome evolution. / Ph. D.

No description available.

Reed canarygrass (Phalaris arundinacea) is adapted to low wet lands and survives flooding and periods of drought. Much of the valley bottom land of Utah is flooded during part of the year, yet some of this land is very dry late in the summer. This grass could become an important forage for Utah's valley bottom lands if stand establishment could be assured. Low germination percentages and long germination periods under field conditions often result in poor stands.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Thesis (M. Ag. Sci.)--University of Adelaide, Dept. of Genetics, 1954. / Typewritten copy. Comparative study of genes for resistance to bunt (Tilletia caries (D.C.) Tul. and T. foetida (Wallr.) Liro); Cytological investigations in Phalaris called part 2.

Azoxystrobin (AZY), a systemic broad-spectrum fungicide, is applied on crops to control soil-borne pathogenic fungi. This study aimed to determine the effects of AZY on non-target plant species and Glomus intraradices Schenck & Smith, an arbuscular mycorrhizal fungus (AMF) associated with plants' roots. We hypothesized that AZY negatively affects AMF viability; and that, if the plants were dependent on this symbiosis, AZY exerts an indirect detrimental effect on plant growth. To test this, three mycotrophic (Phalaris arundinacea L., Solidago canadense L., Geum canadense Jacq.) and one non-mycotrophic (Chenopodium album L.) native plant species were subjected to five AZY doses with or without AMF. Plants were grown for 60 days in a greenhouse, in individual pots, (4 plants X 2 AMF X 5 AZY X 6 replicates), and mesocosms (1 mes. X 2 AMF X 5 AZY X 6 replicates), and harvested 30 days after spraying, and dry mass was taken. Fresh root samples were used for microscopic assessment of AMF colonization. The results from the individual pot experiment show that the effects of AZY on biomass varied across plant species. AZY led to a significant increase in shoot and root mass of P. arundinacea, and a decrease in shoot mass of AMF inoculated G. canadense. The presence of AMF resulted in a significant increase in root and shoot mass of P. arundinacea, and an increase in root mass of S. canadense and shoot mass of C. album. In the mesocosm experiment AZY did not have a significant effect on the measured parameters, although the presence of AMF significantly increased root, shoot, and total dry mass of G. canadense and P. arundinacea. Conversely, AMF significantly decreased shoot and total dry mass of S. canadense. The results suggest that both direct and indirect effects should be taken into account when assessing the impact of pesticides on non-target plant species.