38 research outputs found
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Biochemical markers of quality in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings : the relationship between survival, root growth potential, freezing and drying damage, and time of lift
The physiological condition of a seedling often determines its ability to survive when planted. However, physiological damage is difficult to determine from external measurement or observation, because a healthy looking seedling can be of poor quality (quality is defined as the ability of a seedling to survive when outplanted). Methods currently used to assess quality rely primarily on the growth performance of a seedling. The most widely used quality evaluation method tests a seedlings ability to initiate and elongate roots, commonly called root growth potential (RGP). Other evaluation methods measure seedling frost hardiness, plant water potential, and speed of bud break. However, these indirect measurements of seedling physiology are often
inaccurate evaluators of quality and are slow to yield results. To obtain a direct measure of the physiological condition of seedlings, and hence a direct measure of seedling quality, biochemical markers were sought for Douglas-fir [Pseudotsuga menziesii
(Mirb.) Franco] plants of varying vigor.
Markers of field survival, growth room survival, RGP (number and total length of
new roots), exposure to freezing and drying conditions, and time of lifting were
identified by measuring a large number of compounds from methanol extracts of the apical shoots of 300 seedlings using high performance liquid chromatography (HPLC).
Data were acquired and processed on a computer, and analyzed with five different
multivariate statistical techniques. Principal component analysis was used as an
exploratory technique to investigate the structure of the data. Stepwise multiple
regression and cluster analysis were used to explore grouping among the treatments and
to identify markers The nature of many of the resulting clusters was not easily
determined using this method. Unknown factors in addition to survival, RGP, and exposure to freezing and drying conditions, appeared to control treatment similarity.
However, it was possible to cluster treatments accurately based on the time seedlings were lifted from the nursery.
Results from stepwise and canonical discriminant analysis imply that markers
identified with these procedures are capable of separating treatments of varying field
survival, growth room survival, RGP, or time of lift. Markers were unable to confirm a
clear separation between seedlings that had been damaged by exposure to freezing or
drying conditions. A strong relationship was observed between survival and RGP as
indicated by shared markers. Biochemical markers can be used to predict the survival of seedlings by classifying plants of unknown survival into predetermined groups. This technique promises to be a rapid, reliable, and quantitative means of evaluating seedling quality
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Repeated sequences associated with inversions and length mutations in the chloroplast genomes of Pseudotsuga and Pinus
To help understand the mechanisms of conifer chloroplast genome evolution, we characterized the nucleotide sequences of Douglas-fir (Pseudotsuga menziesiz) and
Monterey pine (Pinus radiata) chioroplast DNA that are associated with a length
mutation hotspot and inversion. The chloroplast DNA ofthese two conifers are
characterized by shared large inversions that are not found in angiosperms or nonconiferous gymnosperms, and are distinguished from each other by an additional 40-50 kb inversion. We cloned and sequenced common endpoints of the 40-50 kb
inversion from Monterey pine and Douglas-&, and a hypervariable chloroplast DNA region from two individuals of Douglas-fir and one individual of its relative,
Pseudotsugajaponica. We found repeated sequences to be associated with all the observed structural changes in these genomes. The locus of polymorphism in the Pseudotsuga hotspot is characterized by hundreds of base pairs of imperfect, tandem direct repeats flanked by a partially duplicated and intact trnY-GUA gene in direct orientation. Repetitive DNA was likely generated at the time of the partial IrnY gene duplication by slipped-strand
mispairing and these sequences expanded further by unequal crossing-over. At inversion borders, we observed the presence of inverted repeats that were hundreds of
base pairs in length, adjacent tRNA genes, and pseudo-tRNA genes. We propose that
homologous recombination between tRNA genes, with the concomitant pseudo-tRNA gene formation, inversion, and creation of repeated sequences at inversion borders, was
the cause of this rearrangement
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Pollen contamination trends in a maturing Douglas-fir seed orchard
Pollen contamination was investigated in one block (block 4) of a 10-block Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed orchard complex in western Oregon. Blocks (25 clones each) represent different breeding zones; thus, contaminant pollen sources not only included the adjacent natural stand of Douglas-fir, but also other blocks within the
orchard complex. Stored seed lots from five crop years (i.e., 1982, 1985, 1987, 1989, 1990) were sampled (200 seeds each) and assayed at 11 allozyme loci. One seed lot (1982) was found to have a high proportion of seed contaminants and was discarded, leaving five crop years for comparison (including 1980 from a previous study). Despite large increases (up to
6-fold) in pollen production from the first commercial crop in 1980, levels of pollen contamination (m) in block 4 remained high and did not differ significantly among years (mean m^ = 0.489, range 0.421-0.606). On average, 79% of the contaminants since 1985 came from the natural stand; 21% from other orchard blocks. Without spatial isolation from nonorchard pollen sources or intensive pollen management to limit contamination (e.g., bloom delay and supplemental mass pollination), levels of pollen contamination can be quite high, even in mature Douglas-fir seed orchards
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Pollen contamination trends in a maturing Douglas-fir seed orchard
Pollen contamination was investigated in one block (block 4) of a 10-block Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed orchard complex in western Oregon. Blocks (25 clones each) represent different breeding zones; thus, contaminant pollen sources not only included the adjacent natural stand of Douglas-fir, but also other blocks within the orchard complex. Stored seed lots from five crop years (i.e., 1982, 1985, 1987, 1989, 1990) were sampled (200 seeds each) and assayed at 11 allozyme loci. One seed lot (1982) was found to have a high proportion of seed contaminants and was discarded, leaving five crop years for comparison (including 1980 from a previous study). Despite large increases (up to 6-fold) in pollen production from the first commercial crop in 1980, levels of pollen contamination (m) in block 4 remained high and did not differ significantly among years (mean m ^ = 0.489, range 0.421 0.606). On average, 79% of the contaminants since 1985 came from the natural stand; 21% from other orchard blocks. Without spatial isolation from nonorchard pollen sources or intensive pollen management to limit contamination (e.g., bloom delay and supplemental mass pollination), levels of pollen contamination can be quite high, even in mature Douglas-fir seed orchards.Keywords: pollen, Douglas-firKeywords: pollen, Douglas-fi
Genetic Diversity and Population Structure In the Rare, Endemic Baker Cypress ( Hesperocyparis bakeri
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Isozyme variation in Sisyrinchium sarmentosum (Iridaceae)
Sisyrinchium sarmentosum is a rare, duodecaploid plant endemic to the Mt. Adams and Mt. Hood areas of Washington and Oregon. Isozyme variation in six Washington populations was assessed to infer genetic variation in this species. Five of the six sampled populations were monomorphic for the sixteen enzymes surveyed, although at one putative locus one of these populations was monomorphic for an enzyme band pattern not seen in any other population. The sixth population had low levels of variation in two enzymes. This low level of variation has often been observed in very rare species and high polyploids. Apparently, the species has recently gone through a bottleneck, perhaps during its recent origin as a species
Mitigating Scoring Errors in Microsatellite Data from Wild Populations
Microsatellite data are widely used to test ecological and evolutionary hypotheses in wild populations. In this paper, we consider three typical sources of scoring errors capable of biasing biological conclusions: stuttering, large-allele dropout and null alleles. We describe methods to detect errors and propose conventions to mitigate scoring errors and report error rates in studies of wild populations. Finally, we discuss potential bias in ecological or evolutionary conclusions based on data sets containing these scoring errors.This article is from Molecular Ecology Notes 6 (2006): 951, doi:10.1111/j.1471-8286.2006.01449.x.</p
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Isozyme variation in showy stickseed, a Washington endemic plant, and relatives
Hackelia venusta, a rare plant endemic to Chelan County, Washington, USA, consists of two entities that differ most notably by flower colour and geographic location. We evaluated the hypothesis that these entities are separate species using a phenotypic analysis of isoenzyme variation to compare both forms of H. venusta with sympatric and allopatric populations of the closely related H. diffusa var. arida, and with the allopatric taxa H. diffusa var. cottonii and H. diffusa var. diffusa. Enzyme band phenotypes revealed that all populations were variable, with 60 to 80% polymorphic enzyme systems. Most variation was within population, with only 32% among population variation detected. The level of variation was moderate to high in H. venusta populations compared to other Hackelia populations. Enzyme band pattern data support the separation of H. venusta from H. diffusa. However, data do not provide evidence for the taxonomic separation of the two colour forms of H. venusta at the species level. Regardless of the taxonomic recognition of H. venusta colour forms, they should be conserved as rare extremes of Hackelia morphology and habitat preference