N-Acylethanolamines (NAEs) are enriched in seed-derived tissues and are believed to be formed from the membrane phospholipid, N-acylphosphatidylethanolamine (NAPE) via the action of phospholipase D (PLD). In an effort to identify a functional NAPE-PLD in cotton seeds and seedlings, we have screened a cotton seedling cDNA (cotyledon mRNA from 48 h dark grown seedlings) library with a 1.2 kb tobacco partial cDNA fragment encoding the middle third of a putative PLDβ/γ (genbank accession, AF195614) isoform. Six plaques were isolated from the Uni-ZAP lambda library, excised as pBluescript SK(-) phagemids and subjected to nucleotide sequence analysis. Alignment of derived sequences with Arabidopsis PLD family members indicated that the cDNAs represent six different PLD gene products -three putative PLD β isoforms and three putative PLD δ isoforms. The PLD β isoforms, designated Ghpldβ1a, GHpldβ1b and a truncated Ghpldβ1b isoform. Both the full-length PLD β proteins contained characteristic HKxxxxD catalytic domains, a PC-binding domain, a PIP2-binding domain and a C2 domain. In addition both cotton PLD β isoforms had a N-terminal "SPQY" rich domain which appeared to be unique to these PLDs. The three PLD δ isoforms, designated Ghpldδ1a, Ghpldδ1b and Ghpldδ1b-2 encode full-length PLDδ proteins, and like the above PLDs, contained the characteristic catalytic and regulatory domains. The expression of Ghpldδ1b showed hydrolytic and transphosphatidylation activity toward radiolabelled phosphatidylcholine (PC) but it appears Ghpldδ1b does not utilize NAPE as a substrate to produce NAEs nor does it seem to be suppressed by NAEs.

Four species of Phoradendron were examined for seedling morphology: P. bolleanum subsp. densum (on Juniperus), P. californicum (on Prosopis), P. juniperinum subsp. juniperinum (on Juniperus, P. villosum subsp. villosum (on Quercus). The main species used in the study was P. juniperinum, using the other species for comparison. The initial shoot(s) of P. juniperinum may develop from the epicotyl of the developing seedling, from adventitious buds which arise from a cushion of tissue, termed the haustorial cushion, formed beneath the holdfast, or from both positions. When shoots arise only from adventitious buds the original seedling remains attached in a lateral position, often persisting for a number of years, giving the false impression of an autoparasite establishing itself near the base of the plant. In P. bolleanum and P. villosum, initial shoots arise from the epicotyl although adventitious shoots may also develop, particularly in P. bolleanum. In contrast, P. californicum shoots are entirely adventitious in origin, and the initial seedling can frequently be seen near the center of the cluster of adventitious shoots. Cotyledons of all species in the study were found to be persistent and possess a distinctive tip probably resulting from the site of attachment to the endosperm. These distinctive, persistent cotyledons and other clearly identified morphological features, allow to readily distinguish between plumular and adventitious shoots.

No description available.

<p> The experiments described in this thesis were performed to investigate the: 1. Role of nitrate in the growth of maize seedling and 2. Role of amino acids in the assimilation of nitrate by the growing embryo.</p> <p> Nitrate stimulated the germination of Zea mays L. seeds by 10 to 15 percent. Further growth of the embryo axis, up to 6 days, however, was not affected by nitrate. During the early growth of the seedling, endosperm nitrogen was able to support the requirements of the embryo for 6 to 8 days. After a lag of 2 days, the protein content of the embryo increased linearly up to 6 days at a rate of 597 μ g a day. Some increase was observed between 6 and 8 days also. After 8 days, the protein level of embryo plateaued. Addition of 10 mM nitrate caused an increase in the protein and total nitrogen of the embryo only after 6 days. The endosperm mutant of maize, opaque-2, also responded to the nitrate in the same way.</p> <p> The protein content of the primary leaves increased linearly between 5 and 7 days. After 7 days, there is no increase in the leaf protein. Nitrate increased the protein level of primary leaves by 25 percent after 7 days. It protected against the further loss of protein in mature leaf. These results suggest that the primary role of nitrate in the growth of maize seedlings is to prevent protein loss.</p> <p> Out of 8 amino acids tested individually, only lysine and to a lesser extent arginine, inhibited the induction of nitrate reductase in the maize root tips. Different ammonium salts had no effect on the induction of nitrate reductase. The initial rate of induction in opaque-2 mutant (high lysine) was lower than the wild type, W64A (low lysine). From a comparison of the rate of induction of nitrate reductase between young and mature leaf, it was suggested that the amino acid supply from the endosperm may inhibit the induction of nitrate reductase. In the young maize seedling, this effect of amino acids may be more effective in vivo and in this way the assimilation of exogenous nitrate could be restricted, when the endosperm amino acids are supporting the growth of the embryo.</p> / Thesis / Master of Science (MSc)

No description available.

Soil moisture tension had a greater effect on both soil surface temperatures and growth of young Kentucky 31 tall fescue (Festuca arundinacea) seedlings under solar radiation than either wood-cellulose mulch or slope-facing. More growth and lower temperatures occurred at low than high moisture tensions. Mulch did not consistently benefit growth. Slope effects were evident primarily at high tensions: higher temperatures and less growth occurred on south than north slopes. Temperatures (a) within a millimeter above the soil-air interface and (b) below the surface of, yet within the mulch layer seemed the most critical to seedling growth. Inadequate moisture control, a sparse seeding rate, a high mulching rate, and below optimal weather conditions complicated environmental control and produced some ambiguous results. A characterization of surface temperature injury to perennial ryegrass (Lolium perenne) seedlings grown with wood-cellulose mulch at two moisture tensions showed seedling injury to increase with surface temperature while air and soil temperatures had no significant effect. Low moisture tension produced lower surface temperatures and less injury than high tension. / M.S.

The purpose of this study was to investigate seedling recruitment beneath kanuka forest at Tiromoana Bush, North Canterbury. The regeneration of broadleaved tree species is evident throughout Tiromoana Bush. This research aimed to quantify the biotic and abiotic factors influencing the distribution of small and large seedlings of canopy tree species, their relative growth rates, their survival, abundance and composition throughout the forest understorey of Tiromoana Bush. Tiromoana Bush is a forest restoration area of 410 hectares adjacent to the Kate Valley landfill. To determine the future tree species composition at Tiromoana Bush, seedling recruitment, growth and survival was quantified through remeasuring tagged seedlings in 26 permanent vegetation monitoring plots located in the major forest patches at Tiromoana Bush. In addition, seedling data from 78 temporary vegetation survey plots established in three major forest patches were used to assess the influence of different factors on seedling abundance. At Tiromoana Bush, the most common canopy tree species as seedlings in the permanent vegetation monitoring plots was mahoe followed by fivefinger. Mahoe seedling density was significantly affected by canopy openness, distance to seed sources, light index, shrub cover and slope, but not by aspect, basal area and time. For fivefinger, seedlings increased in abundance with time, but the difference was not statistically significant. The relative growth rate of mahoe in the 20-49cm height class (in which most seedlings occurred) was significantly affected by shrub cover, light index and canopy vii openness. Mahoe seedling recruits were significantly affected by light index and canopy openness. Survivability of mahoe was affected by aspect. For fivefinger, individual relative growth rates were significantly affected by canopy openness and light index. Similar results were found for tree species seedlings present in the temporary survey plots provided with mahoe and fivefinger again the most common species, followed by kohuhu. Light index significantly affected golden akeake small seedlings as well as canopy openness. Light index significantly affected ngaio large seedling distribution. Aspect was the only significant factor for kohuhu large seedling distribution. Distance from seed sources significantly affected fivefinger small seedling distribution as seedlings are dependent upon dispersal away from the parent trees. Slope significantly affected the distribution of red matipou small seedlings. The most important environmental attribute influencing seedling abundance is light. This is evident in both the permanent seedling monitoring plots and the temporary vegetation survey plots. Based on data from the temporary vegetation survey plots, mahoe, fivefinger and kohuhu are most abundant suggesting that these three canopy tree species will dominate the forest canopy at Tiromoana Bush once the kanuka starts to senesce.

N-acylation of phosphatidylethanolamine (PE) with free fatty acids catalyzed by N-acyl phosphatidylethanolamine (NAPE) synthase was reported in cotyledons of 24-h-old cotton seedlings. Here I report subcellular localization of this enzyme. Differential centrifugation, sucrose density gradient fractionation,aqueous two-phase partitioning and electron microscopy techniques were utilized to elucidate subcellular site(s) of NAPE synthase. Marker enzymes were used to locate organelles in subcellular fractions. Differential centrifugation indicated that NAPE synthase is present in more than one organelle and it is a membrane bound enzyme. Sucrose density gradient fractionations indicated that NAPE synthase is present in membranes derived from endoplasmic reticulum (ER),Golgi and possibly plasma membrane (PM) but not mitochondria, glyoxysomes or plastids. Aqueous two-phase partitioning experiments with cotton and spinach tissues supported these results but Goigi appeared to be the major site of NAPE synthesis. Electron microscopy of subcellular fractions was used to examine isolated fractions to provide visual confirmation of our biochemical results. Collectively, these results indicate that NAPE is synthesized in plant ER, Golgi and possibly PM.

Orientador: Iraê Amaral Guerrini / Coorientador: Agnaldo Scarassati / Banca: Clarice Backes / Banca: Edivaldo Casarini / Resumo: O presente estudo teve por objetivo comparar os sistema hidropônico e o de fertirrigação no desenvolvimento de mudas da espécie florestal nativa jequitibábranco (Cariniana estrellensis). O experimento foi conduzido no Viveiro da Fazenda Experimental Cantareira, pertencente à Faculdade Integral Cantareira (FIC), no município de Mairiporã - SP - setor de Pesquisa Florestal. Foi estudado o desenvolvimento da Cariniana estrellensis sob dois sistemas de produção: fertirrigação e hidropônico. Os sistemas tiveram quatro parcelas com 25 plantas cada, totalizando 100 plantas por sistema. Para avaliação morfológica não destrutiva realizada a cada 14 dias, considerou-se a altura da planta e o diâmetro do colo das 100 plantas de cada sistema, totalizando 200 plantas e, ao término do experimento, para avaliação morfológica destrutiva, foram consideradas como plantas úteis as 9 centrais, totalizando 36 plantas úteis de cada sistema. A qualidade das mudas produzidas no sistema hidropônico foi superior àquelas do sistema de fertirrigação para os seguintes parâmetros e relações: diâmetro do coleto (D), altura da parte aérea (H), massa seca da parte aérea (MSPA), massa seca total (MST), área foliar (AF), relação altura e diâmetro (H/D), altura e massa seca da parte aérea (H/MSPA), massa seca da parte aérea e do sistema radicular (MSPA/MSR), e o Índice de Qualidade Dickman (IQD). Em função dos resultados obtidos, pode-se inferir que para Cariniana estrellensis o sistema hidropônico proporcionou melhor desenvolvimento, reduzindo o período de produção das mudas / Abstract: This study aimed to compare hydroponics and fertigation systems on seedlings production of native species (jequitibá-branco, Cariniana estrellensis). The experiment was conducted at Cantareira Experimental Farm Nursery, owned by Integral Cantareira College (FIC) at the Forestry Research Sector of Mairiporã, SP. We studied the development of jequitibá branco under two production systems: drip irrigation and hydroponics. The systems presented four plots with 25 plants each, totaling 100 plants per system. It was considered for the non-destructive morphological evaluation the plant height and stem diameter of 100 plants per system, totaling 200 plants. This procedure was conducted every 14 days. At the end of the experiment, the morphological destructive assessment was performed on the central 9 plants, with a total of 36 useful plants per system. The quality of seedlings produced in the hydroponic system was superior to the fertigation system for the following parameters and relations: the collar diameter (D), shoot height (H), shoot dry mass (MSPA), total dry mass (MST), leaf area (LA), height and diameter ratio (H/D), dry mass of shoot and root system (MSPA/MSR), and Dickman Quality Index (IQD). Based on the results, we can infer that the hydroponic system enhanced Cariniana estrellensis, growth reducing the period of seedlings production / Mestre

This research was conducted to determine the effects of temperature and competition on seedling root and shoot growth of cheatgrass (Bromus tectorum L.) and 5 collections of Idaho fescue (Festuca idahoensis. Elmer). For the temperature study, seedlings were grown in environmental chambers with 16 hours day/8 hours night, at temperatures of 5, 10 and l5°C. Root depth was weekly recorded during 9 weeks growth period. Seedlings were destructively harvested after 63 days and evaluated for root and shoot characteristics. At all temperatures, cheatgrass exhibited greater above and below-ground biomass, root depth, total root length, daily root depth rate and shoot height than Idaho fescue. Seedlings of the 5 Idaho fescue collections produced fewer roots and grew slower than seedlings of cheatgrass. As a group, the Idaho fescue collections showed similar root and shoot growth and produced more tillers than cheatgrass, except at 5°C. As temperature increased from 10 to 15 °C, shoot growth of Idaho fescue increased while that of cheatgrass was similar. For the competition study, seedlings were grown in pots in a greenhouse with planting ratios of Idaho fescue to cheatgrass of 1:0, 1:5 and 1:10, and under 2 watering regimes. Seedlings of Idaho fescue were established from transplants grown two months ahead of cheatgrass. Shoot height, tiller and leaf number were weekly recorded. Seedlings were harvested after 49 days and evaluated for aboveground dry weight. Competition from cheatgrass depleted soil moisture and reduced growth of Idaho fescue. Cheatgrass had greater aboveground dry weight and shoot height than Idaho fescue. However, Idaho fescue had greater tiller and leaf number than cheatgrass. In addition, when competing with cheatgrass, remnant Idaho fescue plants were less adversely affected in aboveground dry weight and shoot height than Idaho fescue plants from pristine areas. These results indicated that remnant Idaho fescue plants may be a different ecotype occurring in response to competition and may better tolerate the effect of the interference from cheatgrass. This information may serve as a basis for reestablishment of Idaho fescue in Central Oregon rangelands. / Graduation date: 1993