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Red spruce (Picea rubens Sarg.) and black spruce (Picea mariana (Mill.) B.S.P.) are genetically and morphologically similar but ecologically distinct species. We determined intraspecific seed-source and interspecific variation of red spruce and black spruce, from across the near-northern margins of their ranges, for several light-energy processing and freezing-tolerance adaptive traits. Before exposure to low temperature, red spruce had variable fluorescence (Fv) similar to black spruce, but higher photochemical efficiency (Fv/Fm), lower quantum yield, lower chlorophyll fluorescence (%), and higher thermal dissipation efficiency (qN), although the seed-source effect and the seed-source x species interaction were significant only for Fv/Fm. After low-temperature exposure (-40 degrees C), red spruce had significantly lower Fv/Fm, quantum yield and qN than black spruce, but higher chlorophyll fluorescence and relative fluorescence. Species, seed-source effect, and seed-source x species interaction were consistent with predictions based on genetic (e.g., geographic) origins. Multi-temperature exposures (5, -20 and -40 degrees C) often produced significant species and temperature effects, and species x temperature interactions as a result of species-specific responses to temperature exposures. The inherent physiological species-specific adaptations of red spruce and black spruce were largely consistent with a shade-tolerant, late-successional species and an early successional species, respectively. Species differences in physiological adaptations conform to a biological trade-off, probably as a result of natural selection pressure in response to light availability and prevailing temperature gradients. 相似文献
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Background
High throughput DNA isolation from plants is a major bottleneck for most studies requiring large sample sizes. A variety of protocols have been developed for DNA isolation from plants. However, many species, including conifers, have high contents of secondary metabolites that interfere with the extraction process or the subsequent analysis steps. Here, we describe a procedure for high-throughput DNA isolation from conifers. 相似文献4.
Om P. Rajora 《Euphytica》1989,43(3):207-213
Summary Horizontal starch gel electrophoresis was done to assay 10 enzyme systems in root tips of 14 Populus deltoides x P. nigra clones developed by controlled hybridization and selected in North America, and some clones sharing one or both parents. The genotypes of the clones were determined for 31 loci coding for 10 enzyme systems. The interclonal allozyme variability was controlled by 12 loci. Each of the 14 clones had unique 12-locus genotypes, thus could be distinguished from each other. The clones differed from each other on an average of 4.2 loci. The first two Principal Components from Principal Component Analysis of the clonal allozyme genotype data accounted for 48% of the total variation in the 12 variant loci. 6-Pgd-3, Per-2, 6-Pgd-1, Aco-1 and Per-1 were found to be the most discriminating loci for the clones. The ordination of the clones on Principal Component axes 1 and 2 was in general agreement with the origin of the clones. 相似文献
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Increased use of forest resources and a shrinking forestland base threaten the sustainability of forest genetic resources
and highlight the importance of conservation and sustainable management of these resources. As forest trees are normally the
keystone species of forest ecosystems, their continued existence is essential for many floral and faunal associations of these
ecosystems. Major concepts, challenges and opportunities for conservation of forest genetic resources are briefly discussed
in this paper. The major challenges include population decline and population structure changes due to forest removal and
conversion of forest land to other uses,forest fragmentation, forestry practices, climate change, disease conditions,introduced
pests, atmospheric pollution, and introgressive hybridization. Developing scientifically sound conservation strategies, maintaining
minimum viable population sizes, and deployment of genetically engineered organisms represent other important challenges in
conservation. The usefulness of various biochemical and molecular genetic markers, adaptive traits, and genetic diversity
measures for developing conservation strategies for in situ and ex situ genetic resource conservation are also discussed. Major opportunities for conservation of forest genetic resources include:
use of molecular genetic markers and adaptive traits for developing conservation strategies; in situ conservation through natural reserves,protected areas, and sustainable forest management practices; ex situ conservation through germplasm banks, common garden archives, seed banks, DNA banks, and tissue culture and cryopreservation;
incorporation of disease, pest, and stress tolerance traits through genetic transformation;plantation forestry; and ecological
restoration of rare or declining tree species and populations. Forest genetic resource conservation and resource use should
be considered complementary rather than contradictory to each other.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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A successful attempt has been made to transmit T. evansi orally in dogs and mice by allowing them to feed on infected meat and blood. The infection status was determined by daily examination of blood smears and clinical manifestations of trypanosomiasis. 相似文献
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OBJECTIVE: To determine the infectivity of ovine and caprine strains of Dichelobacter nodosus for both sheep and goats. DESIGN: Pen experiments in which 20 sheep and 19 goats were challenged directly with the two strains, and transmission experiments on pasture, using donors infected by experimental challenge. RESULTS: Sheep and goat strains of D nodosus infected both animal species in experimental challenges. Animals so infected transmitted footrot to both sheep and goats on pasture plots. A significantly smaller proportion of goats than sheep was infected when challenged with either strain. The interval between exposure and development of footrot in goats was longer than in sheep when recipient animals were exposed to infected donors on pasture. The disease was less invasive in goats than in sheep. CONCLUSIONS: With the strains of D nodosus used there was no evidence of host specificity. Direct transmission of footrot can occur between sheep and goats in the same environment. There is a need to include goats in ovine footrot eradication programs and vice versa. 相似文献
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