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1.
Relation of light and nitrogen source to growth, nitrate reductase and glutamine synthetase activity of jack pine seedlings 总被引:5,自引:0,他引:5
Two-month-old jack pine ( Pinus banksiana Lamb.) seedlings were placed in a greenhouse where both nitrogen source and light level were varied. After 4 months, whole seedling biomass, leaf biomass and relative growth rate were greatest in seedlings grown with NH+ 4 /NO/NO− 3 -N and full light (FL) and least in seedlings grown with NO − 3 -N and low light (LL). NO − 3 -seedlings grown under full light and NH+ 4 /NO− 3 -seedlings grown under low light were approximately equal. This indicates that the extra carbon costs of assimilating only NO− 3 -N were similar to the reduction of carbon fixation resulting from a 50% decrease in photon flux density. Percentage and total nitrogen content of needles were greater in seedlings grown under low light independent of nitrogen fertilization. Percentage and total nitrogen content of roots were higher under low light and lower when fertilized with NO− 3 .
Nitrate reductase (NR) activity was higher in roots than in needles, while glutamine synthetase (GS) activity was higher in needles than in roots. Low light resulted in decreased NR activity (mg N)−1 in needles, but not in roots. However, no nitrate was detected in the needles in any treatment. GS activity, on the other hand, was greater under low light in both needles and roots. GS activity in needles is most likely involved with the reassimilation rather than the initial assimilation of ammonium. Some implications of these shifts in enzymatic activity for ecological phenomena in forests are discussed. 相似文献
Nitrate reductase (NR) activity was higher in roots than in needles, while glutamine synthetase (GS) activity was higher in needles than in roots. Low light resulted in decreased NR activity (mg N)
2.
The water relations of shoots of young jack pine (Pinus banksiana Lamb.) seedlings were examined 6 and 15 weeks after the initiation of four different dynamic nitrogen (N) treatments using a pressure-volume analysis. The N treatments produced a wide range of needle N concentrations from 12 to 32 mg g?1 dry mass and a 10-fold difference in total dry mass at 15 weeks. Osmotic potential at full turgor did not change over the range of needle N concentrations observed. Osmotic potential at turgor-loss point, however, declined as N concentrations decreased, indicating an increased ability of N-deficient jack pine plants to maintain turgor. The increase could be attributed largely to an increase in cell wall elasticity, suggesting that elasticity changes may be a common, significant adaptation of plants to environmental stresses. Dry mass per unit saturated water almost doubled as needle N level dropped from 32 to 12 mg g?1 and was inversely correlated to the bulk modulus of elasticity. This suggests that cell wall elasticity is determined more by the nature of its cross-linking matrix than by the total amount of cell wall material present. Developmental change was evident in the response of some water relation variables to N limitation. 相似文献
3.
TIANSHAN ZHA ALAN G. BARR T. ANDY BLACK† J. HARRY McCAUGHEY‡ J. BHATTI§ I. HAWTHORNE† PRAVEENA KRISHNAN† J. KIDSTON† N. SAIGUSA¶ A. SHASHKOV Z. NESIC† 《Global Change Biology》2009,15(6):1475-1487
A large area of boreal jack pine (Pinus banksiana Lamb.) forest in Canada is recovering from clear‐cut harvesting, and the carbon (C) balance of these regenerating forests remains uncertain. Net ecosystem CO2 exchange was measured using the eddy‐covariance technique at four jack pine sites representing different stages of stand development: three postharvest sites (HJP02, HJP94, and HJP75) and one preharvest site (OJP). The four sites, located in the southern Canadian boreal forest, Saskatchewan, Canada, are typical of low productivity jack pine stands and were 2, 10, 29, and 90 years old in 2004, respectively. Mean annual net ecosystem production (NEP) for 2004 and 2005 was ?137±11, 19±16, 73±28, and 22±30 g C m?2 yr?1 at HJP02, HJP94, HJP75 and OJP, respectively, showing the postharvest jack pine stands to be moderate C sources immediately after harvesting, weak sinks at 10 years, moderate C sinks at 30 years, then weak C sinks at 90 years. Mean annual gross ecosystem photosynthesis (GEP) for the 2 years was 96±10, 347±20, 576±34, and 583±35 g C m?2 yr?1 at HJP02, HJP94, HJP75, and OJP, respectively. The ratio of annual ecosystem respiration (R) to annual GEP was 2.51±0.15, 0.95±0.04, 0.87±0.03, and 0.96±0.03. Seasonally, NEP peaked in May or June at all four sites but GEP and R were highest in July. R at a reference soil temperature of 10 °C, ecosystem quantum yield and photosynthetic capacity were lowest for the 2‐year‐old stand. R was most sensitive to soil temperature for the 90‐year‐old stand. The primary source of variability in NEP over the course of succession of the jack pine ecosystem following harvesting was stand age due to the changes in leaf area index. Intersite variability in GEP and R was an order of magnitude greater than interannual variability at OJP. For both young and old stands, GEP had greater interannual variability than R and played a more important role than R in interannual variation in NEP. Based on year‐round flux measurements from 2000 to 2005, the 10‐year stand had larger interannual variability in GEP and R than the 90‐year stand. Interannual variability in NEP was driven primarily by early‐growing‐season temperature and growing‐season length. Photosynthesis played a dominant role in the rapid rise in NEP early in stand development. Late in stand development, however, the subtle decrease in NEP resulted primarily from increasing respiration. 相似文献
4.
Differential screening of a cDNA library constructed from root mRNA from jack pine (Pinus banksiana Lamb.) seedlings exposed to two cycles of drought conditioning identified a S-adenosylmethionine synthetase (sam-s) cDNA. A cDNA encoding the entire open reading frame of SAM-S was identified and characterized. Analysis of the full-length sam-s cDNA revealed that it was 1675 bp, encoded an open reading frame of 393 amino acids and had a predicted protein mass of 43 kDa. Jack pine sam-s was found to be highly similar to several other plant sam-s genes. RNA gel blot analysis showed that sam-s mRNA abundance increased following two cycles of drought conditioning and remained abundant after 3 d of rewatering. Expression of this gene appears to be root-specific. Quantitative slot blot analysis showed that two cycles of drought conditioning caused a 6-fold increase in sam-s mRNA abundance whereas heat shock, cold stress and anoxia did not result in the accumulation of sam-s mRNA. SAM-S enzyme activity increased 2-fold following two cycles of drought conditioning. The increase in the rate of SAM-s enzyme activity was also correlated with changes in rates of ethylene and betaine synthesis, biosynthetic pathways that utilize SAM as a substrate. Ethylene evolution and betaine abundance increased following two cycles of drought conditioning. 相似文献
5.
Ultrastructure of vascular cambial cell cytokinesis in pine seedlings preserved by cryofixation and substitution 总被引:4,自引:0,他引:4
Summary. Trees depend on the secondary vascular cambium to produce cells for new xylem and phloem. The fusiform cells of this lateral
meristem are long and narrow, presenting special challenges for arranging the mitotic spindle and phragmoplast. Fusiform cambial
cells of Pinus ponderosa and Pinus contorta were studied by cryofixation and cryosubstitution which preserved ultrastructure and phases of cytokinesis with a resolution
not previously attained. Membranous structures including the plasma membrane, tonoplast, and those of other organelles were
smooth and unbroken, indicating that they were preserved while the protoplasm was in a fully turgid state. Mitotic spindles
separated daughter chromosomes diagonally across the radial width of the cells. The cell plate was initiated at an angle to
the cell axis between the anaphase chromosomes by a microtubule array which organized vesicles at the phragmoplast midline.
Within the phragmoplast, vesicles initially joined across thin tubular projections and then amalgamated into a tubulo-vesicular
network. Axial expansion of the cell plate generated two opposing phragmoplasts connected by a thin, extended bridge of cell
plate and cytoplasm that was oriented along the cell axis. In the cytoplasmic bridge trailing each phragmoplast, the callose-rich
tubular network gradually consolidated into a fenestrated plate and then a complete cell wall. Where new membrane merged with
old, the parent plasmalemma appeared to be loosened from the cell wall and the membranes joined via a short tubulo-vesicular
network. These results have not been previously reported in cambial tissue, but the same phases of cytokinesis have been observed
in cryofixed root tips and suspension-cultured cells of tobacco.
Received February 11, 2002; accepted May 31, 2002; published online October 31, 2002
RID="*"
ID="*" Correspondence and reprints: Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver,
BC V6T 1Z4, Canada.
Abbreviations: CFS cryofixation and cryosubstitution; ER endoplasmic reticulum; HPF high-pressure freezing; PPB preprophase band. 相似文献
6.
Genetic variability and structure of natural and domesticated populations of Caribbean pine (Pinus caribaea Morelet) 总被引:1,自引:0,他引:1
Y.-Q. Zheng R. A. Ennos 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(5):765-771
Isozyme analysis of seed samples derived from natural and managed populations of the tropical pine Pinus caribaea vars ‘bahamensis’ and ‘caribaea’ was used to assess population genetic structure in its native range and to detect changes
occurring during early domestication of the species. Baseline data from natural populations of the two varieties showed that
populations sampled as seed are characterized by high gene diversity (mean He=0.26) and a low level of inbreeding ( mean Fis=0.15). A UPGMA tree of genetic relatedness among populations indicates that the two varieties represent distinct evolutionary
units. Within each variety there is significant differentiation among populations, and this is greater for the more fragmented
populations of var ‘bahamensis’ (Fst=0.08) than for var ‘caribaea’ (Fst=0.02). Seed from a seed orchard population of var ‘caribaea’ established within its natural range showed no change in genetic
diversity but did show a reduced inbreeding coefficient (Fis=0.09) compared with its progenitor populations, suggesting a decrease in selfing and/or biparental inbreeding. A bulked seed
sample from an exotic plantation of var ‘bahamensis’ in Australia displayed a large increase in the inbreeding coefficient
(Fis=0.324) compared with that found in natural populations, possibly due to elevated self-fertilization. Finally, a bulked seed
sample from an exotic plantation population of var ‘caribaea’ from China showed enhanced genetic diversity, an increase in
the inbreeding coefficient and more linkage disequilibrium than its presumed progenitor populations. It was also genetically
divergent from them. RFLP analysis of chloroplast DNA variation in the Chinese sample suggested that seeds of the related
taxa P. elliottii and P. taeda, or seeds derived from hybridization with these taxa growing in the seed production area, had been included in the seed crop
during harvesting. We conclude that monitoring of appropriate genetic markers may be an effective means of identifying potentially
deleterious genetic changes occurring during forest tree domestication.
Received: 10 August 1998 / Accepted: 8 September 1998 相似文献
7.
We followed the colonization frequency of ectomycorrhizal (EM), vesicular-arbuscular mycorrhizal (VAM), and dark septate
(DS) fungi in 1- to 5-month-old bishop pine seedlings reestablishing after a wildfire. Seedlings were collected on a monthly
basis at either a VAM-dominated chaparral scrub site or an EM-dominated forest site, both of which were burned. In both vegetation
types, fully developed EM were observed from the third month after germination. EM fungi observed on the seedlings from the
scrub site were limited to Rhizopogon subcaerulescens, R. ochraceorubens and Suillus pungens. Seedlings from the forest were colonized by a greater variety of EM fungi including Amanita spp., Russula brevipes and a member of the Cantharellaceae. VAM structures (vesicles, arbuscules or hyphal coils) were observed in the seedling
root systems beginning 1 month after germination at the scrub site and 3 months after germination at the forest site. Seedlings
from the scrub site consistently had more frequent VAM fungal colonization than those from the forest site through the fifth
month after germination. DS fungi were observed in most seedlings from both the scrub and forest sites beginning in the first
month post-germination. We propose that these fungi survived as a resident inoculum in the soils and did not disperse into
the sites after the fire.
Accepted: 14 February 1998 相似文献
8.
L. C. Emebiri M. E. Devey A. C. Matheson M. U. Slee 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(7):1053-1061
Haploid megagametophytes from a full-sib cross of Pinus radiata were used to construct a genetic linkage map for radiata pine based on random amplified polymorphic DNA (RAPD) markers. The
map, which was made from 222 markers, was used to carry out a QTL analysis of growth using measurements made on seedlings
from which these megagametophytes were collected at an early germination stage. Trends in the expression of QTLs for stem
diameter, volume and height were compared using measurements made at 5 months of age, and at 1, 2 and 3 years of age. None
of the observed trends showed complete stability, i.e. none of the putative QTL positions detected at any one age was strongly
expressed at all of the four stages of measurement. However, 45% of the trends showed partial stability, i.e. putative QTLs
significant at one age were also detected at a subsequent age. Trends in QTL expression with age followed one of three patterns:
(1) putative QTLs at some locations showed a gradual linear increase in influence from 5 months of age and were highest at
3 years of age; (2) QTLs detected at 5 months of age gradually became less significant with age; and (3) some putative QTLs
showed a curvilinear increase in effect from 5 months of age, reaching their peak expression at 1 to 2 years, and sometimes
were still detected at 3 years of age.
Received: 10 July 1997 / Accepted: 31 March 1998 相似文献
9.
The acquired freezing tolerance of jack pine seedlings (Pinus banksiana Lamb.) conditioned at low nonfreezing temperatures and short photoperiods was determined by comparison of seedling survival to that of nonconditioned (control) seedlings following exposure to ?5 and ?10°C. Compared to that of controls, survival of conditioned seedlings was markedly increased following exposure to freezing temperatures. A 1-week conditioning treatment significantly increased the survival of the seedlings after exposure to ?5°C, but was less effective on seedlings exposed to ?10°C. Conditioning periods of 2 and 4 weeks resulted in higher survival of seedlings exposed to both ?5 and ?10°C. The changes of two root-plasma-membrane-associated enzyme activities, H+-ATPase and NADH-dependent ferricyanide reductase, were studied in enriched plasma membrane fractions during conditioning and after freezing. Post-freezing activities of both enzymes were enhanced by conditioning at low temperatures and short photoperiods. These changes may be related to the increased frost hardiness also induced by conditioning. 相似文献
10.
L. C. Emebiri M. E. Devey A. C. Matheson M. U. Slee 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(1-2):119-124
Needle-to-stem unit rate (NESTUR) is a stem growth index of conifer seedlings that measures the efficiency of stemwood production
per unit of foliage growth. The random amplified polymorphic DNA (RAPD) technique was applied to haploid DNA from the megagametophytes
of a full-sib radiata pine cross to find markers linked to factors controlling the NESTUR trait. Using the bulked segregant
analysis approach, 23 of 933 primers displayed putative linkage to factors controlling NESTUR. Based on the genotypic analysis
of 174 individuals, two quantitative trait loci (QTLs) controlling NESTUR were identified at ANOVA P-levels of 0.01–0.001. The QTLs were identified by RAPD markers OPE-06450 and OPA-101200, which were linked to each other (r=7%), and UBC-333550, which was not linked to the other two. Linkage to components of NESTUR (increments in stem diameter and stem volume) was
demonstrated for UBC-333550, while the others were not linked to NESTUR components.
Received: 18 December 1996/Accepted: 24 January 1997 相似文献
11.
Tree roots are variable in their growth rates, alternating between periods of elongation and dormancy. This variability may
have a strong influence on root anatomy. In the present study, field-grown Pinus banksiana Lamb. roots were divided into four distinct anatomical regions (i.e. white without mycorrhizae, white with mycorrhizae, condensed
tannin, and cork). Changes in root growth, the proportions of the root system occupied by the various regions, and cortical
plasmalemma surface area (CPSA) were determined for 6- to 9-month-old ectomycorrhizal P. banksiana seedlings during a 3-month period (August through October) in northern Ontario. The region in which the greatest change in
length occurred was the condensed tannin zone, which was also the dominant contributor to root length (up to 74% of total).
The roots of seedlings grown under artificial conditions had the same zones but in different proportions compared to roots
in the field. A correlation was noted between increased root growth, low metacutization, and high soil water availability.
The CPSA data were assumed to be a factor influencing ion uptake capacity in a positive manner. Interestingly, increases in
CPSA were not directly correlated with changes in root length for field-grown seedlings. The primary contributor to CPSA in
the field-grown roots was the ectomycorrhizal zone (approximately 80%). In comparison, the bulk (85%) of the CPSA in the chamber-grown
roots was found in the white root region. The conditions under which the seedlings were grown strongly influenced the anatomy
of their roots.
Received: 27 April 1999 / Accepted: 6 December 1999 相似文献
12.
The role of glutathione and the response of components of the ascorbic acid‐glutathione cycle in cold acclimation and the acquired freezing tolerance of jack pine ( Pinus banksiana Lamb.) seedlings were investigated. An increase in the reduced to oxidized glutathione mole ratio was correlated with the increase in root soluble and membrane‐bound protein thiol concentrations during cold acclimation and after a freeze and thaw event. All the enzymes involved in the ascorbic acid‐glutathione cycle were regulated by low temperatures and increased activities of ascorbic peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase were observed after the conditioning of the seedlings to low temperatures. Our results suggest that these enzymes play a protective role following the exposure of the seedlings to freezing temperatures. 相似文献
13.
S. E. McKeand G. Eriksson J. H. Roberds 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(8):1015-1022
Genotype×environment interactions of individual traits have been assessed in numerous experiments with forest trees. However,
since breeding programs rarely aim at the improvement of a single trait, the impact of G×E on index or composite traits must
also be assessed. In a study with 12-year-old loblolly pine families in the southeastern U.S., G×E variance was of relatively
little importance compared to genetic variance for wood density but was of greater significance for several growth traits.
An index that combined stem volume and wood density to improve dry weight but maintain wood density constant (restricted selection
index) resulted in substantially greater G×E variance compared to either of the component traits. The interaction variance
of an index trait is shown to be a function of the index coefficients and the G×E variances and covariances for its constituent
traits. As a result, for some conditions it surpasses the magnitude of G×E variance for each component trait.
Received: 5 September 1996 / Accepted: 25 October 1996 相似文献
14.
L. C. Emebiri M. E. Devey A. C. Matheson M. U. Slee 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(7):1062-1068
NESTUR (needle-to-stem unit rate) is a stem growth index of conifer seedlings that measures the efficiency of stemwood production
per unit of needle growth, and is related to other seedling traits such as height, stem diameter, stem volume and needle volume.
Quantitative trait loci (QTLs) affecting the expression of stem growth efficiency in radiata pine seedlings were investigated
using a RAPD linkage map constructed from markers scored on haploid, megagametophytic DNA. Four putative QTLs were detected
which accounted for 8.5–36.4% of the population variance. A search for evidence of epistasis, using both complete pairwise
and conditional interactions, did not yield any statistically significant result. Over a 3-year period, seedlings with high-NESTUR
marker alleles showed a superior growth performance of 17–40% for height, diameter and volume over those with low-NESTUR marker
alleles.
Received: 10 July 1997 / Accepted: 31 March 1998 相似文献
15.
Fire can cause severe nitrogen (N) losses from grassland, chaparral, and temperate and boreal forest ecosystems. Paradoxically,
soil ammonium levels are markedly increased by fire, resulting in high rates of primary production in re-establishing plant
communities. In a manipulative experiment, we examined the influence of wild-fire ash residues on soil, microbial and plant
N pools in a recently burned Californian bishop pine (Pinus muricata D. Don) forest. Ash stimulated post-fire primary production and ecosystem N retention through direct N inputs from ash to
soils, as well as indirect ash effects on soil N availability to plants. These results suggest that redistribution of surface
ash after fire by wind or water may cause substantial heterogeneity in soil N availability to plants, and could be an important
mechanism contributing to vegetation patchiness in fire-prone ecosystems. In addition, we investigated the impact of fire
on ecosystem N cycling by comparing 15N natural abundance values from recently burned and nearby unburned P. muricata forest communities. At the burned site, 15N natural abundance in recolonising species was similar to that in bulk soil organic matter. By contrast, there was a marked
15N depletion in the same species relative to the total soil N pool at the unburned site. These results suggest that plant uptake
of nitrate (which tends to be strongly depleted in 15N because of fractionation during nitrification) is low in recently burned forest communities but could be an important component
of eco- system N cycling in mature conifer stands.
Received: 29 June 1999 / Accepted: 24 October 1999 相似文献
16.
Regeneration of garlic callus as affected by clonal variation, plant growth regulators and culture conditions over time 总被引:3,自引:0,他引:3
A long-term regeneration system for garlic (Allium sativum L.) clones of diverse origin was developed. Callus was initiated on a modified Gamborg's B-5 medium supplemented with 4.5 μM 2,4-D and maintained on the same basal medium with 4.7 μM picloram+0.49 μM 2iP. Regeneration potential of callus after 5, 12 and 16 months on maintenance medium was measured using several plant growth
regulator treatments. The 1.4 μM picloram+13.3 μM BA treatment stimulated the highest rate of shoot production. Regeneration rate decreased as callus age increased, but healthy
plantlets from callus cultures up to 16-months-old were produced for all clones. Regeneration of long-term garlic callus cultures
could be useful for clonal propagation and transformation.
Received: 24 September 1998 / Revision received: 27 January 1999 / Accepted: 26 February 1999 相似文献
17.
Z. Kaya M. M. Sewell D. B. Neale 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):586-592
Quantitative trait loci (QTLs) for annual height- and diameter-increment growth were estimated in each of two three-generation
loblolly pine pedigrees. Annual height-increment was measured in three consecutive years in the BASE pedigree and in four consecutive years in the QTL pedigree. Annual diameter-increment was measured only in the QTL pedigree for two consecutive years. An interval mapping-approach was used to estimate the number of QTLs, the magnitude of
QTL effects, and their position on genetic linkage maps. Thirteen different height-increment and eight different diameter-increment
QTLs were detected, suggesting that the these traits are, at least in part, controlled by a few genes of large effect. Little
evidence was found for the expression of individual QTLs in multiple years or in multiple genetic backgrounds. These results
were discussed in terms of the power of the experiment and their consequences for marker-assisted breeding.
Received: 12 July 1998/Accepted: 5 August 1998 相似文献
18.
A Genetic linkage map of Pinyon pine (Pinus edulis) based on amplified fragment length polymorphisms 总被引:1,自引:0,他引:1
S. E. Travis K. Ritland T. G. Whitham P. Keim 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(5-6):871-880
Amplified fragment length polymorphisms (AFLP) were used to rapidly generate a dense linkage map for pinyon pine (Pinus edulis). The map population consisted of 40 megagametophytes derived from one tree at Sunset Crater, Arizona. A total of 78 primer
combinations, each with three to five selective nucleotides, amplified 542 polymorphic markers. Of these, 33 markers showed
significant deviation from the expected Mendelian genotypic segregation ratio of 1 : 1, and 164 showed complete linkage with
another marker. This resulted in 338 unique markers mapping to 25 linkage groups, each of which ranged from 2 to 22 markers,
averaging 80 centiMorgans (cM) in size and covering 2,012 cM (2,200 cM with the inclusion of 25 cM for each of 7 unlinked
markers). Pairwise linkage values gave a genome size estimate of 2,390 cM, suggesting comprehensive coverage of the genome.
A search for subsets of primer combinations giving the best map coverage found 10 primer combinations which together marked
72% of the linkage map to within 10 cM; an additional 10 primer combinations increased this percentage to 85%. Our map represents
an initial step towards the identification of quantitative trait loci associated with pest resistance and water stress in
pinyons and will further allow us to examine introgression rates between P. edulis and P. californiarum.
Received: 14 October 1997 / Accepted: 29 April 1998 相似文献
19.
Saturation mapping of a major gene for resistance to white pine blister rust in sugar pine 总被引:6,自引:1,他引:5
D. M. Harkins P. A. Skaggs A. D. Mix G. E. Dupper M. E. Devey B. B. Kinloch Jr. D. B. Neale G. N. Johnson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(8):1355-1360
The molecular basis of resistance to diseases in plants can be better understood if the genes coding for resistance can be
cloned. The single major dominant gene (R) that confers resistance to the white pine blister rust fungus (Cronartium ribicola Fisch.) in sugar pine (Pinus lambertiana Dougl.) has been previously mapped. The objectives of the present study were to saturate the region flanking R with tightly
linked markers and to construct genetic maps for each of four individual seed trees. Bulked segregant analysis (BSA) and haploid
segregation analysis were employed to identify random amplified polymorphic DNA (RAPD) markers linked to R. Automated PCR
analysis was used to assay 1115 primers with susceptible and resistant DNA pools from each of four seed trees (8920 PCR reactions).
Thirteen RAPD loci were identified that were linked to R. The linkage analyses programs JoinMap 1.4 and Mapmaker 2.0 were
used to order RAPD loci relative to R and to construct maps for each of the individual seed trees. Two seed trees, 5701 and
6000, had a large number of tightly linked markers flanking R. These trees will be used in subsequent high-resolution mapping
experiments to identify very tightly linked markers to facilitate the eventual cloning of R.
Received: 1 May 1998 / Accepted: 13 July 1998 相似文献
20.
Mycorrhizal short roots of Pinus contorta Dougl. ex Loud colonized by Suillus variegatus (Sow. ex Fr.) O. Kuntze or Paxillus involutus (Batsch) Fr. were collected 1–>60 days after fungal contact. The proteins of the inoculated roots were extracted, electrophoretically
separated, blotted and immunostained for α-tubulin and actin. The development of the mycorrhiza was also followed microscopically.
The signal of plant α-tubulin was stronger than the signal of fungal α-tubulin during the first 5 days in S. variegatus mycorrhiza and was then exceeded by fungal α-tubulin. This correlated well with the increase of fungal mycelium in the mycorrhiza.
A transient drop in both plant and fungal α-tubulin signals was observed 20 days after fungal contact, suggesting a change
in the metabolism of the mycorrhiza. The signals for plant and fungal actins in the mycorrhiza increased steadily during early
infection and then remained at a high level as the mycorrhiza matured. Similar trends were observed in P. contorta–P. involutus mycorrhiza. The data from P. contorta–S.variegatus mycorrhizas suggests that α-tubulin is a growth-related protein, subject to changes, while the amount of actin reflects the
general metabolic activity of the mycorrhiza. In both mycorrhizal systems clear α-tubulin and actin signals were detected
60 days after colonization, which indicates that the mycorrhizas were metabolically active in spite of their withered appearance.
Accepted: 6 May 1996 相似文献