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1.
Two molecular genetic screening techniques, RAPD (random amplified polymorphic DNAs) and ISSR (inter-simple sequence repeats), were applied to detect the level and pattern of genetic diversity of Monochoria vaginalis, a common weed of rice fields, in seven populations from southern China. Among these populations, 116 bands were amplified by 18 RAPD primers, of which 34 bands (29.31%) were polymorphic, and 14 ISSR primers produced 111 bands with 87 polymorphic bands (78.38%). Within each population, a relatively low level of genetic diversity was detected by both RAPD and ISSR analyses, with a mean genetic diversity (H) of 0.0348 and 0.0551 respectively. Analysis of molecular variance of the data from the RAPD and ISSR markers detected that the majority of total genetic variation existed among populations (73.50% and 76.70% respectively) and only minor genetic variation within populations (26.50% and 23.30% respectively). Cluster analysis divided the seven populations into two groups, indicating that the genetic relationships among populations have relatively low correlation with their geographical distribution (Mantel test; r = 0.45 and 0.48 respectively). Our results indicated that both RAPD and ISSR markers were effective and reliable for accurately assessing the degree of genetic variation of M. vaginalis. Comparing the two techniques, ISSR markers were more efficient than the RAPD assay. The Mantel test gave r = 0.16, suggesting no correlation between these two molecular markers. 相似文献
2.
Rhizoctonia solani AG1IA is an important fungal pathogen causing significant yield and quality losses in rice production. However, little is known about the levels of genetic diversity and structure of this pathogen in North India. Out of 240 samples collected from different rice-growing regions of North India, 112 isolates were identified as R. solani AG1IA subgroups using species-specific primers. All 112 isolates were organized into four groups on the basis of percent disease index (PDI). The majority of the isolates were weakly virulent. Population genetic analysis was performed within and between populations using inter simple sequence repeat (ISSR) markers. A total of 8249 alleles were identified from the 112 isolates of R. solani AG1IA through analysis of the ten inter simple sequence repeat markers. All the ten ISSR markers were polymorphic. The average number of bands per primer was 7.3 which ranged in size from 250 to 1500 bp. Genetic structure of the isolates using inter simple sequence repeat primers showed high degree of polymorphism (PIC ≥0.81). The analysis of molecular variance (AMOVA) indicated that most of the genetic diversity occurred within populations (60%), while the variability among populations and among regions contributed 25 and 15%, respectively. Overall, the present study reveals that a large variation exists among rice-infecting isolates of R. solani AG1IA in North India. Fingerprinting of the isolates using ISSRs along with phenotypic characterization and virulence analysis will help epidemiological studies that can provide new insights into pathogen biology and disease spread. 相似文献
3.
Solanum elaeagnifolium (silverleaf nightshade) is a problematic weed that is common in Jordan and difficult to control. The weed exhibits distinct morphological variations in growth habit, leaf shape, leaf margins, flower colour and presence or absence of spines between individuals among and within populations suggesting genetic differences. Genetic variations among 61 samples of S. elaeagnifolium collected from heavily infested sites in the central Jordan Valley were investigated using six simple sequence repeat (SSR) markers and eight amplified fragment length polymorphism (AFLP) primer combinations. Results showed that 111 out of 675 AFLP bands were polymorphic generating polymorphism information content (PIC) of 38.0%, while 23 SSR polymorphic alleles were detected generating a PIC of 30.8%. Phylogenetic analysis using RaxML software identified four major clades with a clear clustering of the samples with their collection sites. Genetic analysis using both techniques revealed high level of genetic diversity among S. elaeagnifolium samples collected from a small geographical area indicating that a range of genetic diversity may be detected in weed populations across the country that may complicate its management. 相似文献
4.
陕西省苹果树腐烂病菌基因多态性的ISSR分析 总被引：3，自引：1，他引：2
为了从分子水平上揭示苹果树腐烂病菌的群体遗传多样性,采用正交设计对ISSR-PCR体系进行了4因素3水平的筛选,并从47条ISSR引物中筛选出11条多态性较好的引物。对供试的87个分离株进行扩增的结果显示,11条引物在129个位点扩增出稳定的条带,其中多态性位点119个,多态性位点率为92.25%。POPGENE分析显示,病菌种群的遗传多样性和基因多态性丰富,群体间的遗传分化系数(Gst)为0.109,群体内为0.891,群体内多样性大于群体间多样性。两个地理种群间的居群每代迁移数(Nm)为2.046,两者之间存在广泛的基因交流。在遗传相似系数为0.88时,可将21个自然种群划分为9个不同的类群,表明陕西省苹果树腐烂病菌的各个自然种群之间的遗传亲缘关系与其地理来源之间无明显的相关性。 相似文献
5.
Non‐target site resistance to flucarbazone,imazamethabenz and pinoxaden is controlled by three linked genes in Avena fatua 
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下载免费PDF全文 Extensive herbicide usage has led to the evolution of resistant weed populations that cause substantial crop yield losses and increase production costs. The multiple herbicide‐resistant (MHR) Avena fatua populations utilised in this study are resistant to members of all selective herbicide families, across five modes of action, available for A. fatua control in US small grain production, and thus pose significant agronomic and economic threats. Resistance to acetolactate synthase and acetyl‐CoA carboxylase inhibitors is not conferred by known target site mutations, indicating that non‐target site resistance (NTSR) mechanisms are involved. Understanding the inheritance of NTS MHR is of upmost importance for continued agricultural productivity in the face of the rapid increase in resistant weed populations worldwide. As few studies have examined the inheritance of NTSR in autogamous weeds, we investigated the inheritance and genetic control of NTSR in the highly autogamous, allohexaploid species A. fatua. We found that NTSR in MHRA. fatua is controlled by three separate, closely‐linked nuclear genes for flucarbazone‐sodium, imazamethabenz‐methyl and pinoxaden. The single‐gene NTSR inheritance patterns reported here contrast with other examples in allogamous species and illustrate the diversity of evolutionary responses to strong selection. 相似文献
6.
Genetic structure of the invasive Chromolaena odorata in China 总被引：8，自引：0，他引：8
Chromolaena odorata is one of the world's worst tropical weeds, and it can be found in Guangdong, Guangxi, Hainan and Yunnan provinces in China. Genetic variation of 27 C. odorata populations sampled from across its invasive range in China was investigated using inter‐simple sequence repeats (ISSR) analysis. All populations exhibited low levels of genetic variation. On average, 2.35% of the ISSR loci were polymorphic, total genetic diversity (HT) was 0.0406 and Shannon's information index (Hsp) was 0.0623. High genetic identities (I) between populations (0.9687 ± 0.01204) indicated low genetic differentiation. A frequent founder effect was interpreted as the main cause of the genetic structure observed in C. odorata. 相似文献
7.
M. Villarino I. Larena F. Martinez P. Melgarejo A. De Cal 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(4):511-524
The genetic diversity of Spanish and French field populations of Monilinia fructicola, a quarantine fungal pathogen in Europe, was compared with that of Californian, Uruguayan, and New Zealand M. fructicola populations using inter simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) markers. Unweighted pair-group
method with arithmetic average (UPGMA) cluster analysis and principal component analysis (PCA) of the ISSR data set revealed
that the Spanish and French M. fructicola isolates were more closely related between themselves than to the non-European isolates. The levels of genetic diversity
in the Spanish and French isolates are lower than those of the non-European isolates, indicating that M. fructicola is a recently introduced pathogen. UPGMA cluster analysis and PCA of the combined ISSR + RAPD data set of the European M. fructicola populations revealed that the Spanish isolates were more closely related among themselves than with the French isolates.
Analysis of molecular variance partitioned the genetic variance to among the two regions (Spain and France) (20%), among the
regional populations (35%), and within the populations in each region (45%) suggesting restricted gene flow between the three
European populations. The observed index of association (IA) in each European M. fructicola populations indicates that the French and Spanish populations of M. fructicola are mainly asexually reproducing, with the Sudanell population potentially having a teleomorphic stage. The present finding
of low genetic diversity in the Spanish and French M. fructicola populations is probably due to founder effects and genetic drift. 相似文献
8.
Echinochloa crus-galli (L.) P. Beauv. (barnyardgrass) is an annual weed that is native to Asia and found throughout the world. The broad ecological
tolerance and competitive ability of E. crus-galli makes it the most important weed species in rice. Genetic studies of plants are becoming increasingly common because reliable
information is necessary to better understand population dynamics, occurrence of herbicide resistance, and demographic data.
Echinochloa crus-galli populations from 34 different locations in Turkey were compared with respect to morphological differences and genetic variation.
For morphological variation, five seeds of each population were sown in pots and grown in a screenhouse using a randomized
block design. Morphological parameters such as germination speed, flowering time, leaf area, plant height, spikelet length,
above-ground biomass, root dry weight and number of seeds were measured. Distinct differences among populations with respect
to hierarchical cluster analysis were observed. Genetic variations among populations were performed using random amplified
polymorphic DNA (RAPD) markers. The seven RAPD primers amplified 55 bands whose molecular weight varied between 200 and 4000 bp.
The percentage of polymorphic bands was 74.54%. Results showed high morphological and genetic variability among individual
genotypes within geographic locations. Phenotypic and genetic variability among E. crus-galli populations would be influenced by agricultural practices, crop characteristics, geographic location and herbicide pressure.
Differences between weed populations may affect response to chemical or biological control. 相似文献
9.
亚洲小车蝗Oedaleus asiaticus Bei-Bienko是我国北方草原和农牧交错区的主要害虫。为评价内蒙古地区亚洲小车蝗种群的遗传多样性和遗传分化,应用ISSR标记方法对内蒙古15个亚洲小车蝗种群遗传多样性及遗传分化进行了分析。结果表明,7条引物扩增出85条ISSR条带,均为多态性条带。多态性比例（P）、Nei''s遗传多样性指数（H）和香农多样性指数（I）分别为82.59%、0.2319和0.3421,表明亚洲小车蝗种群具有较高的遗传多样性。基因流（Nm）和基因分化系数（Gst）分别为1.2298和0.3352,表明亚洲小车蝗不同地理种群具有明显的遗传分化。遗传距离与地理距离呈极显著正相关关系。表明地理距离和地形差异可能是形成亚洲小车蝗种群遗传分化的主要原因。 相似文献
10.
ABSTRACT The genetic structure of Septoria passerinii from nine field populations was examined at several scales (within lesions, among lesions in a leaf, among leaves in a field, and among fields in North Dakota and western Minnesota) by using amplified fragment length polymorphism (AFLP) markers. A total of 390 isolates were sampled from seven barley fields located in North Dakota and two barley fields located nearby in western Minnesota in 2003 and 2004. Based on 57 polymorphic AFLP markers, AFLP DNA fingerprints identified 176 different genotypes among 390 (non-clone-corrected) isolates in nine different fields. In two intensively sampled sites, ND16 (Williston, ND) and ND17 (Langdon, ND), only one to four different genotypes were found within a lesion. A higher level of genetic and genotypic diversity was found within a leaf in which six to nine different genotypes were found from lesions on a leaf. The genetic diversity within a leaf was similar to the genetic diversity within a field. The average genetic diversity (H) within a field across all AFLP loci was approximately 0.3, except at site ND12 (Carrington, ND) where it was 0.16. Genotypic diversity was high in all populations, and with the exception of ND15 (Rothsay, MN), very low multilocus linkage disequilibrium values ( r(d)) were found in all populations. The population differentiation, G(ST), was relatively high (G(ST) = 0.238) among the nine populations due to the high G(ST) in ND12, ND14 (Twin Valley, MN), and ND15. Population differentiation without those three populations was 0.09. A lack of correlation between geographical distance and genetic distance was found, suggesting the potential for a high level of gene flow between different geographical regions. The population genetic structure described in this study for S. passerinii in North Dakota and western Minnesota is consistent with that of a sexually reproducing fungus. 相似文献
11.
应用ISSR-PCR分析福建水稻纹枯菌的遗传多样性 总被引：5，自引：0，他引：5
本研究应用简单序列重复区间(inter-simple sequence repeats,ISSR)标记技术对福建省10个县市100个水稻纹枯病菌菌株的遗传多样性进行了分析。从16个随机引物中筛选出3个重复性好、特异性高的引物对菌株进行ISSR-PCR扩增,共产生41个ISSR分子标记,其中90.2%的片段具有多态性。PopGene分析结果表明,种群的平均多态位点百分率为55.14%,Shannon表型多样性指数I平均为0.2953,具有较高的遗传多样性;种群间存在着明显的遗传分化(Nei′s信息多样性指数h平均值为0.1991,Gst平均值为0.6423),聚类分析可将它们分成5个遗传聚类群。同时还进行了菌株生长速率和致病力的测定。ISSR遗传聚类组群的划分与菌株的地理来源有明显的相关性,但与菌株的致病力和生长速率都没有明显的相关性。以上结果为进一步开展水稻纹枯病菌群体遗传分析和纹枯病防治提供了一定的理论依据。 相似文献
12.
To reveal the effects of herbicide selection on genetic diversity in the outcrossing weed species Schoenoplectus juncoides, six sulfonylurea‐resistant (SU‐R) and eight sulfonylurea‐susceptible (SU‐S) populations were analysed using 40 polymorphic inter‐simple sequence repeat loci. The plants were collected from three widely separated regions: the Tohoku, Kanto and Kyushu districts of Japan. Genetic diversity values (Nei's gene diversity, h) within each SU‐S population ranged from h = 0.125 to h = 0.235. The average genetic diversity within the SU‐S populations was HS = 0.161, and the total genetic diversity was HT = 0.271. Although the HS of the SU‐R populations (0.051) was lower than that of the SU‐S populations, the HT of the SU‐R populations (0.202) was comparable with that of the SU‐S populations. Most of the genetic variation was found within the region for both the SU‐S and SU‐R populations (88% of the genetic variation respectively). Two of the SU‐R populations showed relatively high genetic diversity (h = 0.117 and 0.161), which were comparable with those of the SU‐S populations. In contrast, the genetic diversity within four SU‐R populations was much lower (from h = 0 to 0.018) than in the SU‐S populations. The results suggest that selection by sulfonylurea herbicides has decreased genetic diversity within some SU‐R populations of S. juncoides. The different level of genetic diversity in the SU‐R populations is most likely due to different levels of inbreeding in the populations. 相似文献
13.
Genetic variation within and between 34 populations of Eichhornia crassipes (water hyacinth) in China was surveyed using random amplified polymorphic DNA (RAPD) markers. A total of 1009 individuals were analysed, for which 12 RAPD primers amplified 69 reproducible bands, with 22 (32%) being polymorphic. The percentage of polymorphic loci (p) within a population ranged from 4.4% to 17.4%, and the mean Nei's gene diversity (He) was 0.046 ± 0.0145, indicating a low genetic diversity of E. crassipes in China. Each population contained at least four RAPD phenotypes (genotypes), and the same particular genotype was invariably dominant in all the populations sampled. The mean proportion of distinguishable genotypes was 0.29. Analysis of molecular variance revealed a large proportion of genetic variation (83.9%) residing within populations and a slightly larger proportion (88.1%) within localities, indicating a low genetic differentiation of E. crassipes populations, both locally and regionally. Human-mediated dispersal, vigorous clonal growth, and a generally low level of sexual reproduction were thought to be responsible for such a pattern of genetic structure. 相似文献
14.
山东省小麦禾谷孢囊线虫rDNA-ITS序列特征和基于ISSR的遗传多样性分析 总被引：1，自引：1，他引：0
小麦孢囊线虫病(CCN,Heterodera avenae)已成为山东省小麦生产上的一种重要病害,研究CCN群体间和群体内的遗传多样性可以为其综合防治提供理论依据。本实验研究了山东省17地市34个群体的r DNA-ITS区,并采用ISSR分子标记技术对其中10个地市的27个种群做了遗传多样性分析。结果表明,在r DNA-ITS系统发育树中,山东省34个小麦孢囊线虫群体与H.pratensis、H.australis及中国H.avenae群体亲缘关系较近。3个ISSR引物共扩增出31条条带,多态性条带百分率(PPB)为100%。菏泽、潍坊、烟台群体遗传多样性较高,枣庄、威海、淄博、滨州群体遗传多样性相对较低。M antel检测和聚类结果表明,群体间的遗传分化与地理距离并无显著的相关性,AM OVA分析结果显示,在总的遗传变异中17.7%的变异发生在群体间,82.3%的变异发生在群体内。研究结果显示山东省H.avenae具有较高的遗传多样性,且群体间已发生了一定程度的遗传分化。 相似文献
15.
The genetic diversity of specific Fusarium oxysporum f.sp. lini from six provinces in China was investigated using molecular markers, inter-simple sequence repeats (ISSR). Based on the morphological features and the internal transcribed spacer (ITS) sequences, 96 isolates were identified as Fusarium oxysporum. The 96 isolates were amplified by PCR with 12 ISSR primers. The number of bands amplified by each primer ranged from 43 to 142, with sizes ranging from 250 to 4,500 bp. A total of 800 bands were observed, out of which 797 were polymorphic (99.62%). The percentage of polymorphic loci varied from 17.25% in Gansu and Inner Mongolia to 33.75% in Sinkiang. Nei’s gene diversity index (h) ranged from 0.0428 in Gansu to 0.0666 in Sinkiang, and Shannon’s information index (I) ranged from 0.0675 in Gansu to 0.1117 in Sinkiang. The genetic identity using the Nei’s genetic identity varied from 0.9643 between the populations from Hebei and Gansu to 0.9844 between the populations from Sinkiang and Shanxi. Unweighted pair group mean analysis (UPGMA) cluster analysis, as indicated by the Nei’s genetic distance, showed the distances ranging from 0.0158 between the populations from Sinkiang and Shanxi to 0.0364 between the populations from Hebei and Gansu. The six populations were clustered into three subgroups. The Gansu population was clustered into one subgroup, the same as the Inner Mongolia population. The four other populations were clustered into the third subgroup. The Nei’s GST (0.2972) and gene flow among populations (Nm =1.1825) revealed large gene exchanges among populations. 相似文献
16.
Schoenoplectus juncoides is one of the most harmful weeds found in East Asian paddy fields. Recent emergence of biotypes that are resistant to the herbicide sulfonylurea (SU) has made weed control difficult. To examine the effect of the evolution of this herbicide resistance on genetic diversity within local populations, we investigated microsatellite variability within and among paddy field populations of S. juncoides in Kinki, Japan. In vivo assay of acetolactate synthase activity and root elongation assay in the presence of SU revealed that of 21 populations, five were sulfonylurea‐susceptible (SU‐S) and eight were completely sulfonylurea‐resistant (SU‐R). The remaining eight populations were a mixture of SU‐S and SU‐R individuals. The average gene diversity for SU‐R populations (HS = 0.168) was lower than those for SU‐S (HS = 0.256) and mixed (HS = 0.209) populations, but the difference was not significant. This indicates that positive selection for SU‐R phenotype did not cause a genome‐wide reduction in genetic diversity. Genetic differentiation among S. juncoides populations was higher than that observed for most weed species studied previously. Although populations in neighbouring paddy fields showed a high level of differentiation, Bayesian clustering analyses suggested that some level of gene flow occurs among them and that the genetic exchange or colonisation between neighbouring populations could contribute to the geographical expansion of the resistant allele. 相似文献
17.
Nguyen Thi Ninh Thuan Joseph Bigirimana Ed Roumen Dominique Van Der Straeten Monica Höfte 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(4):381-396
Rice blast caused by Pyricularia oryzae is a devastating disease worldwide. In Vietnam, rice blast is especially severe in the Red River Delta in the North. The
genetic diversity of 114 P. oryzae isolates collected from rice in 2001 in the Red River Delta and nine additional Vietnamese P. oryzae isolates was analysed using Amplified Fragment Length Polymorphism (AFLP). DNA similarity and cluster analysis based on 160
polymorphic AFLP markers showed twelve different AFLP genetic groups among the 123 field isolates. Isolates collected from
japonica hosts clustered separately from indica host isolates with at least 60% dissimilarity with little evidence for gene flow between the two populations. In the 2001
population originating from indica hosts, three genetic groups were predominant and represented 99% of the isolates sampled. One predominant clonal lineage
represented 59% of the 2001 indica host population and was found in eleven provinces in the Red River Delta of North Vietnam. Significant genotype flow could
be demonstrated between the indica population south of Red river and the indica population north of Red river. There was significant linkage disequilibrium between the AFLP loci within the indica population, indicating that this is not a random mating population. Pathogenicity tests of 25 isolates selected from the
12 AFLP groups on a set of 29 differential rice lines revealed two avirulent isolates and 23 pathotypes. Different combinations
of known resistance genes were found to have potential for blast resistance breeding for North Vietnam.
First two authors contributed equally 相似文献
18.
Stagonospora nodorum blotch, caused by Phaeosphaeria nodorum, is considered one of the most destructive foliar diseases of wheat in the United States. However, relatively little is known about the population biology of this fungus in the major wheat-growing regions of the central United States. To rectify this situation, 308 single-spore isolates of P. nodorum were analyzed from 12 populations, five from hard red spring wheat cultivars in Minnesota and North Dakota and seven from soft red winter wheat in Indiana and Ohio. The genetic structure of the sampled populations was determined by analyzing polymorphisms at five microsatellite or simple-sequence repeat (SSR) loci and the mating type locus. Although a few clones were identified, most P. nodorum populations had high levels of gene (H(S) = 0.175 to 0.519) and genotype (D = 0.600 to 0.972) diversity. Gene diversity was higher among isolates collected from spring wheat cultivars in North Dakota and Minnesota (mean H(S) = 0.503) than in those from winter wheat cultivars in Indiana and Ohio (H(S) = 0.269). Analyses of clone-corrected data sets showed equal frequencies of both mating types in both regional and local populations, indicating that sexual recombination may occur regularly. However, significant gametic disequilibrium occurred in three of the four populations from North Dakota, and there was genetic differentiation both within and among locations. Genetic differentiation between the hard red spring and soft red winter wheat production regions was moderate (F(ST) = 0.168), but whether this is due to differences in wheat production or to geographical variation cannot be determined. These results suggest that sexual reproduction occurs in P. nodorum populations in the major wheat-growing regions of the central United States, and that geographically separated populations can be genetically differentiated, reflecting either restrictions on gene flow or selection. 相似文献
19.
Evaluation of six commonly used reference genes for gene expression studies in herbicide‐resistant Avena fatua biotypes 下载免费PDF全文
下载免费PDF全文 Avena fatua of the family Poaceae is one of the most common and economically damaging grass weeds. Resistance to herbicides that inhibit acetyl‐coenzyme A carboxylase and acetolactate synthase activities has recently been detected in A. fatua. The resistance may be due to mutations in the herbicide targets and/or enhanced herbicide metabolism resulting from changes in gene expression, including in genes involved in detoxifying herbicide active ingredients. To analyse gene expression, stable housekeeping genes must be experimentally determined and used for data normalisation. In this study, A. fatua plants were treated with different herbicide types and plant materials were harvested at three time points following treatment. Six candidate reference genes (18S rRNA, ACT, EF1α, GAPDH, TBP, and TUB) were selected, sequenced and analysed by RT‐qPCR. The resulting data were assessed using four algorithms from the RefFinder software to determine gene expression stability. We identified TBP and GAPDH as the most stably expressed A. fatua reference genes following herbicide treatment. 相似文献
20.
Genetic structuring and diversity patterns along rivers – local invasion history of Ambrosia artemisiifolia (Asteraceae) along the Danube River in Vienna (Austria) shows non‐linear pattern 下载免费PDF全文
下载免费PDF全文 Ambrosia artemisiifolia is an annual weed from North America that nowadays is invasive in many countries worldwide. In Austria, numerous populations of A. artemisiifolia are located along the Danube River, especially along the ‘New Danube’ (Vienna). This area is characterised by ruderal and riparian sites, which are regularly flooded. To better understand the spread of A. artemisiifolia and its colonising behaviour along the Danube River, we analysed genetic structure and diversity based on 23 populations linearly arranged along the Viennese Danube riverbed and upstream, utilising the Amplified Fragment Length Polymorphism (AFLP) fingerprint method. We generated 284 polymorphic AFLP markers across 446 A. artemisiifolia plants. The genetic diversity within populations was higher (HW = 0.091) than among populations (HB = 0.007). This result indicates A. artemisiifolia introductions from similar mixtures of sources or spread from a single already mixed introduction. Within our local setting, we were unable to identify neither source or sink populations nor an obvious linear genetic structuring. Genetic among‐population differentiation was low to moderate (amova ‐derived FST = 0.124). Lack of geographical structuring is indicative of highly dynamic gene flow, which is further supported by the absence of an isolation‐by‐distance pattern. Multiple introductions and non‐directional gene flow are most likely promoted by anthropogenic disturbance and human‐mediated dispersal. Our results demonstrate the ability and speed of A. artemisiifolia to settle in newly disturbed areas and the difficulties to predict invasion directions, as downstream river dispersal was negligible. 相似文献