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1.
Resource sharing through rhizomes of clonal plants supplements locally available nutrients to enhance recruitment and growth in resource‐limited environments. We investigated whether Arundo donax, an invasive clonal plant, can benefit from clonal integration. Sharing resources between ramets can facilitate resprouting from mowing, fire and herbicide treatments, but it is unknown whether clonal integration contributes to A. donax invasion success. Our first objective was to determine whether A. donax rhizomes transported water between ramets. Hydrogen isotopic–enriched water was applied on three 1 m diameter areas, and rhizome and soil samples were collected beyond the watering zone after 5, 24 and 48 h of the last watering. Logistic modelling indicated that water was able to move laterally at least 3.5 m. The second objective was to determine whether clonal integration enhanced growth and survival of A. donax ramets. We compared growth‐related responses in paired 1 m2 plots with severed and intact rhizomes. In the first 19 days, rhizome severing nearly doubled ramet density, while by 77 days, the intact rhizomes produced 67% taller stems with 49% greater diameter and showed higher survival rate after flooding. This study provides initial evidence that physiological integration could be an important mechanism in A. donax, which can enhance its competitive abilities, accelerate rates of encroachment and strengthen its capability to recolonise disturbed areas. Our results highlight an important consideration of clonal invasive species in weed management. 相似文献
2.
Ash dieback is caused by Hymenoscyphus fraxineus, a cryptic species of the putatively harmless Hymenoscyphus albidus. Recently, H. fraxineus was found to be native to East Asia. However, the virulence of Asian H. fraxineus strains on Fraxinus excelsior and the virulence of European H. albidus on hosts other than F. excelsior and Fraxinus mandshurica have not yet been assessed. In a wound inoculation study, the virulence of four H. albidus and four European and Japanese H. fraxineus strains was assessed on F. excelsior and Fraxinus pennsylvanica in a climate chamber. Lesion lengths were measured after approximately three and a half months. No lesions were observed on the negative control or on trees inoculated with H. albidus. In contrast, inoculation with H. fraxineus induced typical symptoms of ash dieback on both tree species. Japanese H. fraxineus strains induced significantly longer lesions compared to European strains. Fraxinus excelsior was highly susceptible and developed lesions averaging lengths of 1·7 and 8·4 cm for European and Japanese strains, respectively. Fraxinus pennsylvanica was less susceptible and developed average lesion lengths of 1·6 and 4·8 cm for European and Japanese strains, respectively. Most strains were successfully reisolated from necrotic lesions or inocula, fulfilling Koch's postulates. The data show that additional introductions of H. fraxineus strains from the native range to Europe could pose a threat to the conservation of F. excelsior. In addition, introduction of H. fraxineus to North America could potentially have a negative effect on the indigenous F. pennsylvanica. 相似文献
3.
Megan Herod;Jason Martina; 《Weed Research》2024,64(1):54-64
Understanding how invasive species respond to changes in abiotic factors and what influences their ability to colonise newly disturbed areas is necessary to predict species expansion, prioritise management efforts, and develop ecological models. We conducted a fully factorial greenhouse experiment using rhizome fragments to examine the effects of four nutrients levels, three soil moisture levels, and two light levels (with five replicates, n = 120) on the growth and resource allocation patterns of Arundo donax, a large-statured invasive wetland species. We predicted that A. donax's performance-related traits—traits that directly influence the functionality and fitness of an individual—such as aboveground biomass (AGB), belowground biomass (BGB), net photosynthesis, and average stem height, would be highest under high light, high soil moisture and high nutrient conditions due to the ability of aggressive invasive species to capitalise on greater resource availability. Analyses using general linear mixed-effects models revealed significant interactions between soil moisture and light. Plants grown in saturated, high light conditions exhibited the highest values for performance-related traits. However, contrary to predictions, nutrients did not significantly influence these traits. Multivariate analysis of variance demonstrated that nutrients did influence biomass allocation patterns, with plants grown with added nitrogen and phosphorus displaying higher AGB:BGB and stem:leaf ratios. This research highlights A. donax's unique response to nutrient addition and the plasticity of biomass allocation patterns. By understanding how invasive species respond to common abiotic factors, we can better predict their expansion and prioritise management efforts, such as focusing on areas of low overstory shading, while also providing crucial information for ecological model development. 相似文献
4.
The population structure of Alternaria species associated with potato foliar diseases in China has not been previously examined thoroughly. Between 2010 and 2013, a total of 511 Alternaria isolates were obtained from diseased potato leaves sampled in 16 provinces, autonomous regions or municipalities of China. Based on morphological traits and molecular characteristics, all the isolates were identified as Alternaria tenuissima, A. alternata or A. solani. Of the three species, A. tenuissima was the most prevalent (75·5%), followed by A. alternata (18·6%) and A. solani (5·9%). Phylogenetic analysis based on sequences of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) of representative Alternaria isolates showed that A. solani was distinct from the two small‐spored Alternaria species. Phylogenetic analysis of the partial coding sequence of the histone 3 gene divided the same collection of isolates into three main clades representing A. tenuissima, A. alternata and A. solani, respectively. The pathogenicity of the isolates on detached leaves of potato cv. Favorite did not differ significantly between the three species or between isolates from different geographical origins. The results indicate that the population structure of Alternaria species associated with potato foliar diseases differs from that reported previously in China. This is the first report of A. tenuissima causing potato foliar diseases in China. 相似文献
5.
Dothistroma needle blight (DNB), caused by Dothistroma septosporum, is the most important disease currently affecting pine plantations in Britain. Intraspecific variation in susceptibility to DNB has been observed in several pine species, but it is not clear if similar variation occurs in Pinus sylvestris (Scots pine), Britain's only native pine. In three separate experiments 2‐ and 3‐year‐old Scots pine saplings from six native Scottish populations were artificially inoculated with D. septosporum conidial suspensions and incubated under conditions optimal for disease development. Conidial suspensions were produced using a single isolate from northeast Scotland. In one experiment, plants were also treated with various spore suspension concentrations to assess the impact of inoculum load on disease severity. There were no significant interactions between host population, plant height, and experiment/inoculum load (anova , P > 0·05), but population, height and inoculum load all significantly affected disease severity (anova , P < 0·05). Among the 2‐year‐old trees, those from Amat were less susceptible than those from Glen Loyne and Glen Cannich (anova , P < 0·05). Among the 3‐year‐old trees, those from Beinn Eighe were less susceptible than those from Abernethy. Plant height and DNB susceptibility had a slightly negative relationship. The use of a spore suspension with a concentration of 1·6 × 106 spores mL?1 was optimum for disease development. In an in vitro experiment, production of conidia was greater when cultures were incubated in darkness. This paper is the first to report intraspecific variation in DNB susceptibility within Scots pine. 相似文献
6.
The fungal genus Alternaria comprises a large number of asexual taxa with diverse ecological, morphological and biological modes ranging from saprophytes to plant pathogens. Understanding the speciation processes affecting asexual fungi is important for estimating biological diversity, which in turn affects plant disease management and quarantine enforcement. This study included 106 isolates of Alternaria representing five phylogenetically defined clades in two sister sub‐generic groups: section Porri (A. dauci, A. solani and A. limicola) and section Alternaria (A. alternata/tenuissima and A. arborescens). Species in section Porri are host‐specific while species in section Alternaria have wider host ranges. For each isolate, DNA sequences of three genes (Alt a1, ATPase, Calmodulin) were used to estimate phylogenies at the population and species levels. Three multilocus haplotypes were distinguished among A. dauci isolates and only one haplotype among A. solani and A. limicola isolates, revealing low or no differentiation within each taxon and strong clonal structure for taxa in this section. In contrast, 37 multilocus haplotypes were found among A. alternata/tenuissima isolates and 21 multilocus haplotypes among A. arborescens isolates, revealing much higher genotypic diversity and multiple clonal lineages within taxa, which is not typical of asexual reproducing lineages. A species tree was inferred using a Yule Speciation model and a strict molecular clock assumption. Species boundaries were well defined within section Porri. However, species boundaries within section Alternaria were only partially resolved with no well‐defined species boundaries, possibly due to incomplete lineage sorting. Significant association with host specificity seems a driving force for speciation. 相似文献
7.
Prunus mahaleb (Saint Lucie's cherry) is a fleshy‐fruited small rosaceous tree, native to the Mediterranean region that has been extensively used as a rootstock species for commercial orchard trees. It has been widely introduced in several countries, becoming invasive in many regions, including the Pampas region of southern Argentina. We studied the reproductive performance of trees spontaneously growing in natural grasslands inside a protected area, estimating age at first reproduction and analysing changes in fruit production, age, canopy volume and basal stem diameter associated with different soil types: rock crevices on hillsides, deep soils in valleys and deep soils in stream‐side habitats. Fruit production starts at the age of 3–6 years, and it can be abundant, even for young plants. We found evidence that fecundity is related to plant size, and that the age at which individuals reach a particular size and begin fruiting differs depending on the soil type where they grow. Trees in the study area show an order of magnitude increase in fruit production on reaching ages from 7 to 10 years for plants growing in deep soils at stream‐side habitats and 13–16 years for plants growing in rock crevices. Invasive trees should be felled before they reach a basal stem diameter of c. 9 cm to avoid this increase in propagule pressure. Considering that the age at which this stage is reached depends on soil type, the streams could act as dispersal corridors for the spread and invasion of this species. 相似文献
8.
Solidago canadensis is native to North America, but has become a noxious invasive plant in China. We know only a little about its invasion history and the effects of introductions on its genetic composition. Here, we investigated genetic variation and structure between 15 North American and 13 Chinese populations of S. canadensis using AFLP makers. Four AFLP loci suggested relatively high genetic diversity of this weed and similar genetic variation between the invasive range and the native range. Most genetic variation was within populations across two ranges, but the Chinese range had a higher degree of among‐population variation than the North American range. Multiple tests, including Bayesian assignment, UPGMA analysis, PCoA and analysis of ‘isolation by distance’, showed that the Chinese populations originated from at least two distinct native sources and that secondary introduction or dispersal should be common in China. Also, North American populations were possibly a single genetic group. Overall, S. canadensis in China was probably founded from multiple introductions and then spread through long‐distance dispersal associated with human activities. Genetic variability in the species in the invaded range appears to have favoured establishment and spread and may well provide a challenge to successful control. 相似文献
9.
Although preference for NH4+, NO3? or a combination of the two often differs among species, we know little about the responses of invasive plants to different inorganic N forms. Furthermore, many studies have suggested that an increase in N availability may facilitate further invasions. However, most of these studies predicted the positive feedback without considering the preference for N forms of invasive plants. Therefore, we cultivated four common invasive species (Mikania micrantha, Ipomoea cairica, Wedelia trilobata and Bidens pilosa) in South China with hydroponic media containing different forms of N (i.e. NO3?, NH4NO3 and NH4+) at equimolar concentrations. Our results showed that the N forms significantly affected the growth, biomass allocation and physiological traits of the plants. All four invasive plants supplied with NO3? alone had better performance and greater allocation to root biomass than did plants that were supplied with NH4+ alone. Moreover, the photosynthetic rate, pigment content and photosystem II activity of plants supplied with NO3? or NH4NO3 were significantly higher than those of plants supplied with NH4+alone. The results suggested that all four invasive plants preferred NO3? rather than NH4+, and changes in NO3? played an important role in furthering the invasions of these plants than did changes in NH4+. Our results implied that decreasing NO3? may be a useful tool for controlling and managing invasive plants preferring NO3?. In addition, this study highlighted the importance of considering plant N form preference to better understand plant invasions. 相似文献
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11.
The rapid expansion of the alien invasive Parthenium hysterophorus is a new agricultural and environmental problem for Nepal. Although the weed was first recorded in 1967, the most significant expansion has occurred in the last 20 years. The weed is thought to have entered Nepal from India and currently is found in the Tarai, Siwalik and hill regions of Nepal. A CLIMEX modelling projection has shown these regions to be climatically suitable for the growth of P. hysterophorus, both under the present and a future projected increased temperature. From the initially invaded roadside vegetation, the weed has now spread into cropping land and forests. Vehicle movement and transportation of agriculture products are the main means by which its seed is spreading. The weed has reduced plant species richness and changed species composition in grasslands, while fodder collectors have developed contact dermatitis from the plant. To date, no sustainable management strategy has been developed for this weed. However, the fortuitous arrival of the biological control agents Zygogramma bicolorata and Puccinia abrupta var. partheniicola has had some impact upon the weed's growth and abundance. A CLIMEX modelling projection identifies many suitable locations for Z. bicolorata outside of its present range and within areas where the weed is likely to spread, both under the present and under a future projected climate of increased temperature. Mapping of the currently invaded areas, management through community involvement and further releases of new and redistribution of current biological control agents are required to manage P. hysterophorus in Nepal. 相似文献
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13.
Species composition and genetic structure of Fusarium graminearum species complex populations affecting the main barley growing regions of South America 
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下载免费PDF全文 E. Castañares M. I. Dinolfo E. M. Del Ponte D. Pan S. A. Stenglein 《Plant pathology》2016,65(6):930-939
Members of the Fusarium graminearum species complex (FGSC), such as F. graminearum and F. asiaticum, are the main cause of fusarium head blight (FHB) of wheat and barley worldwide. In this study, 117 FGSC isolates obtained from commercial barley grain produced in Argentina (n = 43 isolates), Brazil (n = 35), and Uruguay (n = 39) were identified to species and trichothecene genotypes, and analysed using amplified fragment length polymorphism (AFLP) and sequence‐related amplified polymorphism (SRAP) markers. In addition, reductase (RED) and trichothecene 3‐O‐acetyltransferase (Tri101) were sequenced for a subset of 24 isolates. The majority of the isolates (n = 103) were identified as F. graminearum, which was the only species found in Argentina. In Uruguay, only one F. cortaderiae isolate was found among F. graminearum isolates. In Brazil, F. graminearum also dominated the collection (22/35), followed by F. meridionale (8/35), F. asiaticum (2/35), F. cortaderiae (2/35) and F. austroamericanum (1/35). Species were structured by trichothecene genotype: all F. graminearum were of the 15‐acetyldeoxynivalenol (ADON), F. meridionale, F. asiaticum and F. cortaderiae were of the nivalenol (NIV), and F. austroamericanum was of the 3‐ADON genotype. Both AFLP and SRAP data showed high levels of genetic variability, which was higher within than among countries. Isolates were not structured by country of origin. SRAP analysis grouped F. graminearum in a separate cluster from the other species within the complex. However, AFLP analysis failed to resolve the species into distinct clades with partial clustering of F. meridionale, F. austroamericanum, F. asiaticum and F. graminearum isolates. 相似文献
14.
The pathogenicity of some Phytophthora species recently described from Western Australia, together with P. cinnamomi as a control, was tested against seven Western Australian native plant species in the glasshouse. Host species were Banksia grandis, B. littoralis, B. occidentalis, Casuarina obesa, Corymbia calophylla, Eucalyptus marginata and Lambertia inermis. Twenty‐two Phytophthora species were grown on a vermiculite, millet seed and V8 substrate and used as soil inoculum when the plant hosts were approximately 3 months old. Pathogenicity was assessed after 6 weeks and plants were scored for death, root damage, and percentage reduction of shoot growth compared with control plants. The pathogenicity of P. cinnamomi was confirmed. Phytophthora niederhauserii was shown to be similar to P. cinnamomi in pathogenicity and of concern ecologically. Other species that killed one or more hosts were P. boodjera, P. constricta, P. elongata, P. moyootj and P. rosacearum, while P. condilina, P. gibbosa, P. gregata, P. litoralis and P. ‘personii’ caused significant reduction to shoot and/or root growth, but did not kill plants. Host species susceptible to the highest number of Phytophthora species were B. grandis, B. littoralis, B. occidentalis and E. marginata. No Phytophthora species tested killed C. calophylla. 相似文献
15.
Despite their putative invasive potential, Miscanthus taxa have been increasingly viewed as promising crops for bioenergy production. Miscanthus x giganteus is cultivated worldwide due to its high productivity, and its non‐spreading growth limits its risk of invasion. However, the genetic uniformity of its unique cultivated clone has recently been questioned. We used morphometry, nuclear microsatellites, AFLP fingerprints and nrDNA ITS barcoding to assess Miscanthus genotypes cultivated in eastern France. As expected, the globally cultivated clone was the main morphotype and genotype of our samplings; however, we also identified a second genotype, assigned to M. sacchariflorus, in the sampled fields. Morphological differentiation partially overlaps genotypic assignation, probably due to disturbance at the crop edges. We also show that Miscanthus taxa are misidentified in commercial nurseries. Our study confirms previous reports of the occurrence of other accessions in fields of M. x giganteus. These taxonomic confusions limit the certainty that a single clone of M. x giganteus is cultivated. In this context, M. x giganteus crop fields may actually promote the dispersal of invasive Miscanthus taxa. 相似文献
16.
J. Crozier C. Arroyo H. Morales R. L. Melnick M. D. Strem B. T. Vinyard R. Collins K. A. Holmes B. A. Bailey 《Plant pathology》2015,64(6):1385-1395
Frosty pod rot (FPR), caused by Moniliophthora roreri, is responsible for significant losses in Theobroma cacao. Due to limited options for FPR management, biological control methods using Trichoderma are being studied. Combinations of three formulations and two Trichoderma isolates were studied between May 2009 and April 2011. The formulations were 0·3 mL L?1 of the surfactant BreakThru 100SL (BT), a mixture of 1% w/v Sure‐Jell (source of pectin) and 1% w/v potato dextrose broth (PDB) (PP), and an invert oil emulsion of 50% v/v corn oil/2·5% w/v lecithin/0·5% w/v PDB (COP). Water and fungicide, copper oxychloride, were included as controls. Humidity chamber studies indicated that Trichoderma conidia germinated in all formulations if free water was maintained, while only the COP formulation supported germination under drying conditions. In the field, Trichoderma ovalisporum DIS‐70a and Trichoderma harzianum DIS‐219f were applied monthly in each of the three formulations at a rate of 180 mL per tree, 2·46 × 107 conidia per mL. The COP/DIS‐70a formulation provided the largest yield increase compared to all other treatments, including the fungicide control. Averaged over the 2 years, the COP formulation increased yield to 30·7% healthy pods compared to 9·7% healthy pods in the water control. Although the formulation/isolate combinations did not consistently increase endophytic colonization, the PP/DIS‐219f, COP/DIS‐219f and COP/DIS‐70a combinations increased total endophytic/epiphytic colonization by Trichoderma. The invert corn oil formulation of DIS‐70a significantly enhanced yield of healthy cacao pods over 2 years providing a promising model for optimizing Trichoderma‐based biocontrol strategies. 相似文献
17.
Evidence of early defence to Ascochyta lentis within the recently identified Lens orientalis resistance source ILWL180 下载免费PDF全文
下载免费PDF全文 In plant–pathogen interactions, strong structural and biochemical barriers may induce a cascade of reactions in planta, leading to host resistance. The kinetic speed and amplitudes of these defence mechanisms may discriminate resistance from susceptibility to necrotrophic fungi. The infection processes of two Ascochyta lentis isolates (FT13037 and F13082) on the recently identified ascochyta blight (AB)‐resistant Lens orientalis genotype ILWL180 and two cultivated genotypes, ILL7537 (resistant) and ILL6002 (susceptible), were assessed. Using histopathological methods, significant differences in early behaviour of the isolates and the subsequent differential defence responses of the hosts were revealed. Irrespective of virulence, both isolates had significantly lower germination, shorter germ tubes and delayed appressorium formation on the resistant genotypes (ILWL180 and ILL7537) compared to the susceptible genotype (ILL6002); furthermore, these were more pronounced on genotype ILWL180 than on genotype ILL7537. Subsequently, host perception of pathogen entry led to the faster accumulation and notably higher amounts of reactive oxygen species and phenolic compounds at the penetration sites of the resistance genotypes ILWL180 and ILL7537. In contrast, genotype ILL6002 responded slowly to the A. lentis infection and reaffirmed previous gross disease symptomology reports as highly susceptible. Interestingly, quantification of H2O2 was markedly higher in ILWL180 particularly at 12 h post‐inoculation compared to ILL7537, potentially indicative of its superior resistance capability. Faster recognition of A. lentis is likely to be a major contribution to the superior resistance observed in genotype ILWL180 to the highly aggressive isolates of A. lentis assessed. 相似文献
18.
Intensification of agricultural practices has severely reduced weed diversity in arable fields, which affects the delivery of ecosystem services. However, in parallel, some species have benefited from intensive farming and have vastly increased their abundance, as is the case for Lolium rigidum and Avena sterilis in cereal fields. These highly competitive species severely reduce yields but can also compete with other weed species, and, when less intensive practices are applied, they might limit the recovery of weed diversity and the success of arable species reintroductions. A gradient of infestation was established in a winter wheat field in Catalonia (north‐eastern Spain) by sowing seeds of both species at three different densities to test their effects on the abundance, diversity and composition of the natural weed community. The emergence of seeds and the survival and biomass of transplanted seedlings of two rare species, Agrostemma githago and Vaccaria hispanica, were also evaluated. Avena sterilis and L. rigidum infestations reduced the diversity, abundance and biomass and changed the composition of the natural weed community, even at low infestation densities. Moreover, infestations of both species affected the overall performance of A. githago and V. hispanica. This study reveals that A. sterilis and L. rigidum are highly competitive and that their infestations might hamper the recovery of diverse weed communities. Their densities should be considered when selecting suitable sites for promoting diversity and reintroducing rare species. 相似文献
19.
Cherry leaf roll virus (CLRV) isolates from Malus domestica, Ribes rubrum, Rubus idaeus, Rumex obtusifolius and Vaccinium darrowii were characterized based on nucleotide sequences of a 371 bp fragment of the 3′ untranslated region (UTR) of their genomic RNAs, symptoms in the herbaceous hosts, Chenopodium amaranticolor, Chenopodium quinoa, Nicotiana benthamiana, Nicotiana occidentalis and Nicotiana tabacum, and seed transmission in N. occidentalis. The different isolates induced a range of localized and systemic disease symptoms, of varying severity, in the herbaceous hosts. The isolates from M. domestica, R. rubrum, R. obtusifolius and V. darrowii all showed greater than 80% seed transmission in N. occidentalis, but no seed transmission was observed for the R. idaeus isolate. Based on symptoms and seed transmission, the isolates appear to be biologically distinct strains of CLRV. Phylogenetic analysis of the nucleotide sequences from the 3′ UTR, commonly used to detect CLRV, showed that four isolates from M. domestica, R. rubrum, R. idaeus and V. darrowii were almost identical but an isolate from R. obtusifolius exhibited a pairwise nucleotide difference of up to 5·4% when compared to these isolates. There was no obvious correlation between sequence differences and symptomatology. 相似文献
20.
Increased resistance to Verticillium dahliae in Arabidopsis plants defective in auxin signalling 下载免费PDF全文
下载免费PDF全文 Auxin signalling and transport participate in plant–microbe interactions as positive or negative regulators of disease resistance. The present study investigated the responses of Arabidopsis thaliana plants impaired in the auxin receptors TIR1, AFB1 and AFB3 and the auxin transporter AXR4, upon infection by the soilborne root pathogen Verticillium dahliae. Fewer symptoms were recorded in afb1, afb3 and axr4 plants compared to the wild type (wt). qPCR analysis revealed that the decrease in symptom severity in afb1, afb3 and axr4 was correlated with reduction in the growth of the pathogen in the plants. Therefore, afb1, afb3 and axr4 are partially resistant to V. dahliae. Upon V. dahliae infection, the expression of TIR1, AFB1, AFB3 and AXR4 was up‐regulated in roots, while indole‐3‐acetic acid levels were similar to mocks. The partial resistance of afb1, afb3 and axr4 against V. dahliae can be attributed in part to the up‐regulation of defence‐related genes, as it was observed that afb1 and axr4 had higher PR1 levels than wt, while afb3 had higher PDF1.2 levels than wt. The findings of the present study suggest that the auxin signalling defective mutants afb1, afb3 and axr4 show increased resistance against V. dahliae. 相似文献