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1.
Juliana Vitória Messias Bittencourt Alexandre Magno Sebbenn 《Conservation Genetics》2008,9(4):855-868
As a matter of fact, Araucaria angustifolia populations occur predominately in small and isolated stands; only a minor number of continuous natural forests of this dioecious
wind-pollinated coniferous tree species remain. To implement reasonable conservation, breeding and restorations program it
is necessary to have the knowledge of pollen dispersal distance and fine-scale genetic structure. In this paper, levels and
dispersion distance of pollen and spatial genetic structure of A. angustifolia were investigated in a 14 ha transect in a continuous forest in Paraná State, Brazil. Analyses have been performed by the
use of eight microsatellite loci, paternity and TwoGener approaches, and spatial autocorrelation analysis. In transect, 52 male and 56 female adult trees were mapped and genotyped,
together with 190 seeds. In the present transect, A. angustifolia show spatial genetic structure at distances up to 75 m. Paternity analysis indicated that 54% of seeds were fertilized by
pollen from trees outside the transect. The calculated average pollination distance within transect was 102 and 98 m based
on the paternity analysis and TwoGener analysis, respectively. We found a significant pollen gene pool structure across seed-trees (
, P < 0.01) that corresponds to an effective number of pollen donors of 6.4 male trees or an effective pollination neighbourhood
area (A
ep
) of 2.1 ha. The findings suggest long-distance pollen dispersion (>100 m) inside the continuous forest. However, the high
proportion occurs in short-distance producing biparental and correlated mating as well as reducing the variance effective
size. 相似文献
2.
Identifying the maternal origin of dispersed seeds is a challenging task because it is impossible to directly track seed movement
once an animal has ingested them. However, recent development of molecular techniques allows us to identify the maternal origin
of dispersed seeds in natural plant populations. Here we analyzed the maternal origin of Myrica rubra seeds found in the feces of Yakushima macaques. We detected a high level of diversity among the dispersed seeds, with an
average of 3.0 maternal origins (range 1–9) in each feces. The average dispersal distance was 270.0 m (range 20.4–634.0 m)
and the average of distance between maternal trees of dispersed seeds in the same feces was 161.5 m (range 0–573.9 m). These
results suggest that seed dispersal by macaques plays an important role in maintaining the genetic diversity of Myrica
rubra populations. 相似文献
3.
Cui-Ping Cao Oliver Gailing Iskandar Z. Siregar Ulfah J. Siregar Reiner Finkeldey 《Tree Genetics & Genomes》2009,5(3):407-420
Shorea is the largest and most important genus of the Dipterocarpaceae. The genetic diversity and structure of nine Shorea species from two different locations, namely Nanjak Makmur in Sumatra and Sumalindo in Borneo, were evaluated using amplified
fragment length polymorphism (AFLP) markers. A total of 274 trees were investigated at 85 polymorphic AFLP loci. Levels of
genetic diversity of these species ranged from = 0.100 for S. acuminata to = 0.165 for S. blumutensis. The population of rare species S. blumutensis possessed the highest genetic diversity suggesting that geographically restricted species can have levels of genetic variation
comparable to closely related widespread common congeners. Analyses of molecular variance revealed that the genetic variation
was mainly found among species in both locations (57.7% in Sumatra; 56.3% in Borneo). The unweighted pairgroup method using
arithmetic averages dendrogram of all samples revealed an almost complete separation of species. Thus, AFLP markers proved
appropriate for phylogenetic studies of Shorea species. Specific markers have been detected showing high-frequency differences among species and between regions within
species. Sequence information of these markers can be used to develop specific polymerase chain reaction markers for wood
identification. The possibility of interspecific hybridization was discussed. 相似文献
4.
Brian S. Baltunis Timothy A. Martin Dudley A. Huber John M. Davis 《Tree Genetics & Genomes》2008,4(4):797-807
Quantifying foliar stable carbon isotope discrimination (Δ) is a powerful approach for understanding genetic variation in
gas exchange traits in large populations. The genetic architecture of Δ and third-year height is described for more than 1,000
clones of Pinus taeda tested on two contrasting sites. for Δ was 0.14 (±0.03), 0.20 (±0.07), and 0.09 (±0.04) at Florida, Georgia, and across sites, respectively. for stable carbon isotope discrimination ranged from 0.25 (±0.03) at the Florida site to 0.33 (±0.03) at the Georgia site,
while the across-site estimate of was 0.19 (±0.02). For third-year height, ranged from 0.13 (±0.05) at the Georgia site to 0.20 (±0.06) at the Florida site with an across-site estimate of 0.09 (±0.05).
Broad-sense heritability estimates for third-year height were 0.23 (±0.03), 0.28 (±0.03), and 0.13 (±0.02) at the Florida
site, Georgia site, and across sites, respectively. Type B total genetic correlation for Δ was 0.70 ± 0.06, indicating that
clonal rankings were relatively stable across sites, while for third-year height, rankings of clones were more unstable across
the two trials . Third-year height and Δ were negatively correlated at the parental , full-sib family , and clonal levels, suggesting that genetic variation for Δ in P. taeda may be a result of differences in photosynthetic capacity. We conclude that Δ may be a useful selection trait to improve
water-use efficiency and for guiding deployment decisions in P. taeda. 相似文献
5.
Influence of inbreeding depression on a lake population of Nymphoides peltata after restoration from the soil seed bank 总被引:1,自引:1,他引:0
Shinichi Takagawa Izumi Washitani Ryuji Uesugi Yoshihiko Tsumura 《Conservation Genetics》2006,7(5):705-716
The negative effects of inbreeding depression on fragmented small populations are likely to be expressed more strongly after restoration efforts if regeneration processes have been highly restricted in degraded habitats. We examined the potential influences of inbreeding depression on a population of Nymphoides peltata (Menyanthaceae) restored from the remnant soil seed bank. A hand-pollination experiment demonstrated self-compatibility of a single remaining homostyle genet and significant inbreeding depression in selfed progeny, especially in parameters related to seedling growth (–0.6 for biomass, and –0.4 for relative growth rate). Our genetic analysis indicated that the presumed number of parents contributing to the current soil seed bank was only 2–8 genets and that a single sib-family dominated at each of three sampling sites. The results also showed that the selfed progeny of the homostyle genet were overwhelmingly dominant at two sites (86.8 and 94.7%). As a result, the growth performance of the seed bank seedlings was significantly reduced, to a level as low as that of the selfed progeny. Active restoration efforts to minimize the negative effects of the genetic bottleneck and continuous monitoring based on genetic and demographic study are recommended. 相似文献
6.
In many dioecious plant species in which spatial distributions of males and females have been examined, the sexes are spatially
segregated – usually along an environmental gradient. Unless pollen is uniformly distributed in a population, spatial segregation
of the sexes should reduce the average mating success of individuals. In three Californian populations of Distichlis spicata – a wind-pollinated grass species that exhibits spatial segregation of the sexes – I examined patterns of pollen movement
and the effects of pollen load and nutrient availability on seed set to determine whether spatial segregation of the sexes
actually reduces mating success for both males and females. In two of the populations, pollen dispersal was restricted, and
pollen augmentation consistently, significantly increased seed set. However, in the third population – which had the lowest
seed set – I found that although there were some indications of pollen limitation, pollen dispersal was not restricted, and
seed production was limited primarily by nutrient availability. These results imply that in some populations of D. spicata nutrient limitation on the production of seeds by females may be sufficiently strong that spatial segregation of the sexes
causes a fairly low cost to reproductive success compared with a more random distribution of the sexes. However, in other
populations, pollen does limit mating success, and the spatial segregation of males and females in these populations is reducing
the fecundity of both males and females. 相似文献
7.
We investigated the genetic differentiation of Rosa canina at regional and continental scales to delineate provenance regions for seed collection. Using RAPD technique, we examined eight populations in Brandenburg (Germany) and 13 samples from Bavaria and Hungary. AMOVA and $\upphiWe investigated the genetic differentiation of Rosa canina at regional and continental scales to delineate provenance regions for seed collection. Using RAPD technique, we examined
eight populations in Brandenburg (Germany) and 13 samples from Bavaria and Hungary. AMOVA and -statistics revealed a significant differentiation ( = 0.23, P < 0.0001) between accessions from Brandenburg and the two other regions. The interpopulation differentiation in Brandenburg
was low ( = 0.13). We found the greatest interpopulation distance between Hungary and Brandenburg (Hoher Fl?ming, = 0.47) and the lowest between Dahmeland and Hoher Fl?ming (both Brandenburg, = 0.01). UPGMA dendrogram and PCA showed a clear disjunction between Brandenburg and other regions. Due to the outcrossing
mating and seed dispersal system, the genetic variation within R. canina populations is moderately high (87% for Brandenburg, 76% for Bavaria and Hungary). The significant genetic differentiation
at the continental scale suggests lower gene flow with increasing geographical distance and underlines the usefulness of regional
provenances for planting. 相似文献
8.
Okada K Tonaka N Moriya Y Norioka N Sawamura Y Matsumoto T Nakanishi T Takasaki-Yasuda T 《Plant molecular biology》2008,66(4):389-400
Japanese pear (Pyrus pyrifolia Nakai) has a gametophytic self-incompatibility (GSI) mechanism controlled by a single S-locus with multiple S-haplotypes, each of which contains separate genes that determine the allelic identity of pistil and pollen. The pistil S gene is the S-ribonuclease (S-RNase) gene, whereas good candidates for the pollen S gene are the F-box protein genes. A self-compatible (SC) cultivar, ‘Osa-Nijisseiki’, which is a bud mutant of ‘Nijisseiki’
(S
2
S
4), has a stylar-part mutant
-haplotype, which lacks the S
4-RNase gene but retains the pollen S gene. To delineate the deletion breakpoint in the -haplotype, we constructed a bacterial artificial chromosome (BAC) library from an S
4-homozygote, and assembled a BAC contig of 570 kb around the S
4-RNase. Genomic PCR of DNA from S
4- and -homozygotes and the DNA sequence of the BAC contig allowed the identification of a deletion of 236 kb spanning from 48 kb
upstream to 188 kb downstream of S
4-RNase. The -haplotype lacks 34 predicted open reading frames (ORFs) including the S
4-RNase and a pollen-specific F-box protein gene (termed as S
4
F-box0). Genomic PCR with a primer pair designed from the deletion junctions yielded a product specific for the -haplotype. The product could be useful as a maker for early selection of SC cultivars harboring the -haplotype.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
Ken Nozawa Takayoshi Shotake Mitsuru Minezawa Yoshi Kawamoto Kenji Hayasaka Sakie Kawamoto Shin-ichi Ito 《Primates; journal of primatology》1991,32(4):411-435
Genetic variability in local populations of the Japanese macaque (Macaca fuscata) was quantified by the proportion of polymorphic loci (Ppoly) and the average heterozygosity per individual (
) from the starch- and polyacrylamide-gel electrophoreses of blood proteins controlled by 32 independent genetic loci. Ppoly averaged 13.6% and
2.1%, the values being at lower level compared with other mammalian species. Geographical distribution of the genetic variations
was not uniform in the whole species but its local differentiation was remarkable. Genetic variability tended to be lower
in the southern localities, especially in the southernmost island of Yaku, than in the central and northern localities. The
genetic distance and the principal component analyses showed that the most divergent local populations were the population
in the Shimokita peninsula at the northernmost distribution area of the species and the populations on the Yaku island at
the southernmost. The most contributory loci to the genetic divergence were the PGM-II, Gc, and Hb-β, the variant allele at the first locus being concentrated in the Yaku island, in the Shimokita peninsula, and in the easternmost
Boso peninsula, and the variant allele at the latter two loci having high frequencies in the Shimokita and the Izu peninsulas.
The Hennigian cladistic analysis, for which the Chinese rhesus macaque (M. mulatta) was used as the outgroup, revealed that the number of presence of derived (apomorphic) alleles was conspicuously smaller
in southern islet populations than in central and northern populations, whereas any areal tendency was not recognized in the
number of loss of ancestral (plesiomorphic) alleles. The observed distribution pattern that the plesiomorphic variant allele
at the PGM-II locus concentrated only in the peripheral (southernmost, northernmost, and easternmost) ranges of the species,
would indicate, as a possibility, the occurrence of two or more waves of immigration of ancestors of the present-day Japanese
macaque from the Asian continent. 相似文献
10.
Genetically engineered pacemaking in ventricular cells has been achieved by down-regulation of the time independent inward rectifying current (I
K1), or insertion of the hyperpolarisation-activated funny current (I
f). We analyse the membrane system (i.e. ionic concentrations clamped) of an epicardial Luo-Rudy dynamic cell model using continuation algorithms with the maximum conductance () of I
K1 and I
f as bifurcation parameters. Pacemaker activity can be induced either via Hopf or homoclinic bifurcations. As
K1 is decreased by ≈74%, autorhythmicity emerged via a homoclinic bifurcation, i.e., the periodicity first appear with infinitely large periods. In contrast, the insertion of
f induced periodicity via a subcritical Hopf bifurcation at
f≈ 0.25 mSμF−1. Stable autorhythmic action potentials occurred at
f > 0.329 mSμF−1. 相似文献
11.
Marilena Martins Pamboukian Soraia Athie Calil Jorge Mariza Gerdulo Santos Adriana Yurie Yokomizo Carlos Augusto Pereira Aldo Tonso 《Cytotechnology》2008,57(1):37-44
Specific respiration rate (
) is a key parameter to understand cell metabolism and physiological state, providing useful information for process supervision
and control. In this work, we cultivated different insect cells in a very controlled environment, being able to measure . Spodoptera frugiperda (Sf9) cells have been used through virus infection as host for foreign protein expression and bioinsecticide production.
Transfected Drosophila melanogaster (S2) cells can be used to produce different proteins. The objective of this work is to investigate respiratory activity and
oxygen transfer during the growth of different insect cells lines as Spodoptera frugiperda (Sf9), Drosophila melanogaster (S2) wild and transfected for the expression of GPV and EGFP. All experiments were performed in a well-controlled 1-L bioreactor,
with SF900II serum free medium. Spodoptera frugiperda (Sf9) cells reached 10.7 × 106 cells/mL and maximum specific respiration rate () of 7.3 × 10−17 molO2/cell s. Drosophila melanogaster (S2) cells achieved 51.2 × 106 cells/mL and of 3.1 × 10–18 molO2/cell s. S2AcGPV (expressing with rabies virus glycoprotein) reached 24.9 × 106 cells/mL and of 1.7 × 10–17 molO2/cell s, while S2MtEGFP (expressing green fluorescent protein) achieved 15.5 × 106 cells/mL and = 1.9 × 10−17 molO2/cell s. Relating to the Sf9, S2 cells reached higher maximum cell concentrations and lower specific respiration rate, which
can be explained by its smaller size. These results presented useful information for scale-up and process control of insect
cells. 相似文献
12.
The effects of population density on male and female reproductive success of Betula maximowicziana were evaluated in two mixed and two post-fire stands, with various population densities, ranging from 1.9 to 300.0 trees
per ha, in central Hokkaido, Japan. First, we investigated ecological determinants of reproductive success (seed set and germination)
of both seeds collected from the trees (tree seeds) and dispersed seeds collected from seed traps (dispersed seeds). We then
evaluated the effects of population density on seed set and germination of tree seeds and dispersed seeds using a generalized
linear mixed model (GLMM). Subsequently, we genotyped 950 seeds collected from mother trees and 940 seeds trapped after dispersal
derived from tree seeds and dispersed seeds, respectively, using eleven microsatellite loci. Using the acquired data, we then
evaluated the outcrossing rate and effective number of pollen donors (N
ep) of the tree seeds, and the genetic structure of both pollen pools and dispersed seed populations. The seed set and germination
rate of dispersed seeds was significantly lower both in the lowest-density stand and in the highest-density stand. The GLMM
revealed that seed set and germination rates of dispersed seeds may be maximal at approximately 120 trees per hectare (optimal
density). Outcrossing rates were consistently high (t
m = 0.995), regardless of the population density. In contrast, N
ep was lower in the lowest-density stands. Significant genetic structure of the dispersed seed population was found in two low-density
stands, probably due to the limitation of overlapping seed shadows. 相似文献
13.
Berchemiella wilsonii var. pubipetiolata (Rhamnaceae) is an endangered plant with only four remnant populations in eastern China. Population genetic information is
essential for understanding population history and formulating conservation strategies for this species. Thirteen microsatellite
loci were used to investigate genetic variation and population structure of the four remnant populations. Moderate levels
of expected heterozygosity (H
E = 0.466–0.543) and low allelic diversity (A = 3.1–3.6 and A
R = 2.2–2.4, respectively) were observed within populations. Bottleneck tests found three out of four populations to deviate
from mutation-drift equilibrium under the two-phase model (TPM), suggesting a recent population decline, which is congruent
with known demographic history. The evolutionary history of the species seems dominated by genetic drift rather than gene
flow. Low historical gene flow was inferred from several different approaches and N
m ranged from 0.582 by the private allele method to 0.783 by the coalescent method. Contemporary gene flow was also found to
be even lower for only one first generation migrant was detected with individual-based assignment analysis. Restricted pollen
and seed dispersal as well as a recent decline in population size associated with habitat fragmentation may have contributed
to low levels of historical and contemporary gene flow, and resulted in a high genetic differentiation. Under this scenario,
Berchemiella wilsonii var. pubipetiolata populations are expected to display more pronounced population genetic structure in the future as a result of increased inbreeding
and genetic drift. 相似文献
14.
Chronic herbivory negatively impacts cone and seed production,seed quality and seedling growth of susceptible pinyon pines 总被引:3,自引:0,他引:3
Although herbivory often reduces the reproduction of attacked trees, few studies have examined how naturally occurring insect-resistant
and susceptible trees differ in their reproduction, nor have these effects been experimentally examined through long-term
herbivore removals. In addition, few studies have examined the effects of herbivory on the quality of seeds produced and the
implications of reduced seed quality on seedling establishment. We evaluated the impact of chronic herbivory by the stem-boring
moth, Dioryctria albovittella, on cone and seed production of the pinyon pine (Pinus edulis) during two mast years. Three patterns emerged. First, moth herbivory was associated with reductions in cone production,
viable seed production and seed mass. Specifically, pinyons susceptible to moth attack had 93–95% lower cone production, and
surviving cones produced 31–37% fewer viable seeds, resulting in a 96–97% reduction in whole tree viable seed production.
In addition, surviving seeds from susceptible trees had 18% lower mass than resistant trees. Second, long-term experimental
removal of the herbivore resulted in increased rates of cone and seed production and quality, indicating that moth herbivory
was the driver of these reductions. Third, seed size was positively associated with seed germination and seedling biomass
and height, suggesting that trees suffering chronic herbivory produce poorer quality offspring. Thus, the resistance traits
of pinyons can affect the quality of offspring, which in turn may affect subsequent seedling establishment and population
dynamics. 相似文献
15.
The mating system of a species is an essential factor that determines the genotypic frequencies of its populations in each
generation. Thus, knowledge in this regard is important in the application of practical measures in conservation and forest
tree breeding. Austrocedrus chilensis (D.DON) PIC. SER. ET BIZZARRI is a member of the Cupressaceae native to the Andean–Patagonian Forest of Argentina and Chile with regional economic importance. It is a dioecious tree with
pollen and seeds distributed by wind. Isozyme markers were utilized to study the mating system of this species through the
survey of individual effective pollen clouds in a natural low-density population. If random mating occurs, effective pollen
clouds that pollinate single seed trees are expected to be genetically homogeneous. The classical HardyWeinberg test of panmixia
was also performed. Although it failed to reject random mating, the analysis of the pollen clouds showed that this mating
pattern does not occur. Evidence of locally distributed heterogeneous pollen clouds is presented. The two methods are critically
compared. 相似文献
16.
Marta Dubreuil Federico Sebastiani Maria Mayol Santiago C. González-Martínez Miquel Riba Giovanni G. Vendramin 《Conservation Genetics》2008,9(6):1665-1668
Seven polymorphic nuclear microsatellite markers for Taxus baccata L. (English yew) were developed using an enriched-library method. An additional polymorphic SSR was obtained by testing eight
primer pairs from the congeneric species Taxus sumatrana. Mendelian inheritance for the seven Taxus baccata SSRs was proved by genotyping 17 individuals and 124 megagametophytes (conifer seed haploid tissue). A total of 96 individuals
from 5 different populations (10–26 samples per population) were used to estimate genetic diversity parameters. High levels
of genetic diversity, with values ranging from 0.533 to 0.929 (6–28 alleles per SSR) were found. No linkage disequilibrium
between pairs of loci was detected. All loci but one showed significant departures from Hardy–Weinberg equilibrium. Excess
of homozygosity was probably due to high inbreeding in English yew populations, an outcome of low effective population size
and/or fragmented distribution. Highly polymorphic SSRs will be used to conduct population genetic studies at different geographical
scales and to monitor gene flow. 相似文献
17.
The effect of temperature on post-feeding ammonia excretion and oxygen consumption in the southern catfish 总被引:1,自引:0,他引:1
Yiping Luo Xiaojun Xie 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2009,179(6):681-689
The post-prandial rates of ammonia excretion (TAN) and oxygen consumption in the southern catfish (Silurus meridionalis) were assessed at 2 h intervals post-feeding until the rates returned to those of the fasting rates, at 17.5, 22.5, 27.5,
and 32.5°C, respectively. Both fasting TAN and increased with temperature, and were lower than those previously reported for many fish species. The relationship between
fasting TAN (mmol NH3–N kg−1 h−1) and temperature (T, °C) was described as: fasting TAN = 0.144e
0.0266T
(r = 0.526, n = 27, P < 0.05). The magnitude of ammonia excretion and its ratio to total N intake during the specific dynamic action (SDA) tended to increase initially, and then decrease with increasing temperature. The
ammonia quotient (AQ), calculated as mol NH3–N/mol O2, following feeding decreased as temperature increased. The relationship between AQ during SDA and temperature was described
as: AQduring SDA = 0.303e
−0.0143T
(r = 0.739, n = 21, P < 0.05). Our results suggest that ammonia excretion and oxygen consumption post-feeding are operating independently of each
other. Furthermore, it appears that the importance of protein as a metabolic substrate in postprandial fish decreases with
temperature. 相似文献
18.
Survivorship and growth of seedlings of four dipterocarp species (Dipterocarpus actangulus, D. globosus, Dryobalanops aromatica, Dryobalanops lanceolata) were studied for 2.5 years in a mixed dipterocarp forest in Sarawak, East Malaysia. Predispersal seed predation rates were
larger forD. globosus (75%) thanD. lanceolata (27–34%) andD. aromatica (18–26%). Less than 20% of the twoDryobalanops seeds were damaged by vertebrates after seed dispersal. During the period from seed dispersal to the time when the seedlings
had shed cotyledons, more dispersed seeds died in the twoDipterocarpus (ca 90%) than the twoDryobalanops (ca 60–70%). The major mortality factors during this period were uprooted and seed/seedling predation by insects or vertebrates.
After the seedlings shed cotyledons, all species showed constant mortality rates of 34, 15–16, 17 and 6%/year forD. actangulus, D. lanceolata, D. aromatica andD. globosus, respectively, in the forest understorey. Mortality was lower in less shaded conditions than in more shaded ones forD. aromatica andD. actangulus, but not significantly different forD. lanceolata andD. globosus. A majority of dead seedlings were killed by fallen branches or were found standing with wilted leaves, probably due to water
stress. No significant correlation was found between seed/seedling mortality and distance from mother trees or the initial
density of seeds/seedings for all species. The mean leaf production was positively correlated with the estimated diffuse light
factor of their habitats for each species. 相似文献
19.
Genetic structure of an insect-pollinated and bird-dispersed tropical tree in vegetation fragments and corridors: implications for conservation 总被引:2,自引:0,他引:2
In the vegetation corridors that connect small remnants of undisturbed primary forest in the Lavras landscape (Brazil), Protium spruceanum is a representative of a mass-flowering insect-pollinated and bird-dispersed tree. Allozyme variation was quantified from
five forest remnants (N = 150) from secondary vegetation corridors linking them (N = 80) to generate information for genetic conservation. The species adhered to H-W equilibrium in all fragments in most of
the loci. The results indicated high gene diversity in the fragments and corridors positively correlated with the plant density (r = 0.742, R
2 = 0.551, d.f. = 4). We did not find evidence of inbreeding within fragments nor overall The genetic differentiation among remnants was low Evidence of recent bottlenecks by anthropogenic disturbance was detected in fragments (P < 0.05, Wilcoxon sign-rank test). The minimal viable population was estimated for conservation in situ, indicating fragments
with possibilities of maintaining genetic equilibrium diversity in the short term (except F3) and in the long term (only F5).
The ratios was also calculated to contribute to vegetation enrichment, area recovery or creation of new vegetation corridors.
We found high levels of gene diversity in the vegetation corridors, genetic identity with the fragments and absence of inbreeding.
Thus, our results suggest that landscape management strategies should therefore consider both the creation of new vegetation
corridors and the protection of extant ones. 相似文献
20.
Can biological nitrification inhibition (BNI) genes from perennial Leymus racemosus (Triticeae) combat nitrification in wheat farming? 总被引:1,自引:0,他引:1
G. V. Subbarao Ban Tomohiro Kishii Masahiro Ito Osamu H. Samejima H. Y. Wang S. J. Pearse S. Gopalakrishnan K. Nakahara A. K. M. Zakir Hossain H. Tsujimoto W. L. Berry 《Plant and Soil》2007,299(1-2):55-64
Using a recombinant luminescent Nitrosomonas europaea assay to quantify biological nitrification inhibition (BNI), we found that a wild relative of wheat (Leymus racemosus (Lam.) Tzvelev) had a high BNI capacity and releases about 20 times more BNI compounds (about 30 ATU g−1 root dry weight 24 h−1) than Triticum aestivum L. (cultivated wheat). The root exudate from cultivated wheat has no inhibitory effect on nitrification when applied to soil;
however, the root exudate from L. racemous suppressed formation and kept more than 90% of the soil’s inorganic-N in the -form for 60 days. The high-BNI capacity of L. racemosus is mostly associated with chromosome Lr#n. Two other chromosomes Lr#J, and Lr#I also have an influence on BNI production.
Tolerance of L. racemosus to is controlled by chromosome 7Lr#1-1. Sustained release of BNI compounds occurred only in the presence of in the root environment. Given the level of BNI production expressed in DALr#n and assuming normal plant growth, we estimated
that nearly 87,500,000 ATU of BNI activity ha−1 day−1 could be released in a field of vigorously growing wheat; this amounts to the equivalent of the inhibitory effect from the
application of 52.5 g of the synthetic nitrification inhibitor nitrapyrin (one AT unit of BNI activity is equivalent to 0.6 μg
of nitrapyrin). At this rate of BNI production it would take only 19 days for a BNI-enabled wheat crop to produce the inhibitory
power of a standard commercial application of nitrapyrin, 1 kg ha−1. The synthetic nitrification inhibitor, dicyandiamide, blocked specifically the AMO (ammonia monooxygenase) pathway, while
the BNI from L. racemosus blocked the HAO (hydroxylamine oxidoreductase) pathway in Nitrosomonas. Here we report the first finding of high production of BNI in a wild relative of any cereal and its successful introduction
and expression in cultivated wheat. These results demonstrate the potential for empowering the new generation of wheat cultivars
with high-BNI capacity to control nitrification in wheat-production systems.
Responsible Editor: Hans Lambers. 相似文献