首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 375 毫秒
1.
ABSTRACT Karnal bunt of wheat is caused by the fungus Tilletia indica, which partially converts kernels into sori filled with teliospores. Despite minor overall yield and quality losses, the disease is of considerable international quarantine concern. Plant development stages reported susceptible to infection vary considerably. A study was designed to better define the susceptibility period by inoculating wheat spikes at different growth stages with naturally liberated secondary sporidia under optimal conditions for disease development. Spikes of a resistant and susceptible cultivar were inoculated at eight growth stages from awns emerging to soft dough. Spikes became susceptible only after emerging from the boot and continued to be susceptible up to soft dough stage at which low levels of disease occurred. Disease severity in both cultivars peaked when spikes were inoculated after complete emergence, but before the onset of anthesis. Disease levels tapered off gradually in spikes inoculated after anthesis. The results broaden the known susceptibility period of wheat to T. indica to include stages long after anthesis, and indicate that infection from airborne inoculum is not possible during boot or awns emerging stages, which are commonly referred to as the most susceptible stages.  相似文献   

2.
We review trends and advances in three specific areas of theoretical plant epidemiology: models of temporal and spatial dynamics of disease, the synergism of epidemiology and population genetics, and progress in statistical epidemiology. Recent analytical modelling of disease dynamics has focused on SIR (susceptible–infected–removed) models modified to include spatial structure, stochasticity, and multiple management-related parameters. Such models are now applied routinely to derive threshold criteria for pathogen invasion or persistence based on pathogen demographics (e.g., Allee effect or fitness of fungicide-resistant strains) and/or host spatial structure (e.g., host density or patch size and arrangement). Traditionally focused on the field level, the scale of analytical models has broadened to range from individual plants to landscapes and continents; however, epidemiological models for interactions at the cellular level, e.g., during the process of virus infection, are still rare. There is considerable interest in the concept of scaling, i.e., to what degree and how data and models from one scale can be transferred to another (smaller or larger) scale. Despite assertions to the contrary, the linkages between epidemiology and population genetics are alive and well as exemplified by recent efforts to integrate epidemiological parameters into population genetics models (and vice versa) and by numerous integrated studies with an applied focus (e.g., to quantify sources and types of primary and secondary inoculum). Statistical plant epidemiology continues to rely heavily on the medical and ecological fields for inspiration and conceptual advances, as illustrated by the recent surge in papers utilizing ROC (receiver operating characteristic), Bayesian, or survival analysis. Among these, Bayesian analysis should prove especially fruitful given the reliance on uncertain and subjective information for practical disease management. However, apart from merely adopting statistical tools from other disciplines, plant epidemiologists should be more proactive in exploring potential applications of their concepts and procedures in rapidly expanding disciplines such as statistical genetics or bioinformatics. Although providing the scientific basis for disease management will always be the raison d’être for plant epidemiology, a broader perspective will help the discipline to remain relevant as more resources are being devoted to genomic and ecosystem-level science.  相似文献   

3.
An ergosterol-deficient mutant of Ustilago maydis was compared to the wild type in regard to morphology, growth rate, lipid content, and sensitivity to ergosterol biosynthetic inhibitors. Morphology of mutant sporidia is abnormal and resembles that of fenarimol-treated wild-type sporidia. Doubling time of mutant sporidia is 6.3 hr compared to 2.5 hr for the wild type. The mutant produces 24-methylenedihydrolanosterol, obtusifoliol, and 14α-methylfecosterol; ergosterol is absent. The sterols of the mutant are the same as those which accumulate in wild-type sporidia treated with the sterol C-14 demethylation inhibitors fenarimol, etaconazole, and miconazole. The level of free fatty acids is higher in the mutant than in wild-type cells. Growth of mutant sporidia is not inhibited by fenarimol, etaconazole, and miconazole, or by the sterol Δ14-reductase inhibitor azasterol A25822B at low concentrations which inhibit growth of wild-type sporidia. The residual growth rate of wild-type sporidia treated with low concentrations of the sterol C-14 demethylation inhibitors is about the same as that of untreated mutant sporidia. Therefore, the mutant would not be recognized as resistant in a wild-type population. The mutant is deficient in sterol C-14 demethylation and is similar in all properties studied to wild-type sporidia treated with sterol C-14 demethylation inhibitors. These findings support the contention that inhibition of sterol C-14 demethylation in U. maydis is the primary mode of toxicity of fenarimol, etaconazole, and miconazole. A secondary mode of toxicity is evident for miconazole and etaconazole at higher concentrations but is doubtful for fenarimol.  相似文献   

4.
ABSTRACT Most models for the spread of fungicide resistance in plant pathogens are focused on within-field dynamics, yet regional invasion depends upon the interactions between field populations. Here, we use a spatially implicit metapopulation model to describe the dynamics of regional spread, in which subpopulations correspond to single fields. We show that the criterion for the regional invasion of pathogens between fields differs from that for invasion within fields. That is, the ability of a fungicide-resistant strain of a pathogen to invade a field population does not necessarily imply an ability to spread through many fields at the regional scale. This depends upon an interaction between the fraction of fields that is sprayed and the reproductive capacity of the pathogen. This result is of practical significance and indicates that resistance management strategies which currently target within-field processes, such as the use of mixtures and alternations of fungicides, may be more effective if between-field processes also were targeted; for example, through the restricted deployment of fungicides over large areas. We also show that the fraction of disease-free fields is maximized when the proportion of fields that is sprayed is just below the threshold for invasion of the resistant strain.  相似文献   

5.
ABSTRACT Ascospore release in 20 populations of Venturia inaequalis was generally suppressed in wind tunnel tests during darkness and simulated rain, but the following relieved this suppression: (i) exposure to low relative humidity during simulated rain and (ii) protracted incubation of leaf samples and the consequent senescence of the pathogen population. No counterpart to (i) was observed under orchard conditions. Although V. inaequalis also released a high percentage of ascospores during darkness in field studies under simulated rain late in the season of ascospore release, this phenomenon has not been reported for natural rain events. A threshold value of 0.5 muW/cm(2) at 725 nm was identified as the minimum stimulatory light intensity. Ascospore release increased with increasing light intensity from 0.5 to 5.2 muW/cm(2) at 725 nm. There was also an intrinsic increase in ascospore release as duration of rain increased. In orchards, the combined impact of both processes is probably responsible for a delay in reaching peak ascospore release at several hours after sunrise. Ascospore release during darkness will generally constitute a small proportion of the total available supply of primary inoculum. Significant ascospore release, and therefore infection periods, can be assumed to begin shortly after sunrise, when rain begins at night in orchards with low potential ascospore dose (PAD). A PAD level of 1,000 ascospores per m(2) of orchard floor per season is suggested as a threshold, above which the night-released ascospores should not be ignored.  相似文献   

6.
Seasonality plays an important role in the dynamics of infectious disease. For vector‐borne pathogens, the effects of seasonality may be manifested in the variability in vector abundance, vector infectiousness, and host‐infection dynamics over the year. The relative importance of multiple sources of seasonality on the spread of a plant pathogen, Xylella fastidiosa, into vineyards was explored. Observed seasonal population densities of the primary leafhopper vector, Graphocephala atropunctata, from 8 years of surveys in northern California were incorporated into a model of primary spread to estimate the risk of pathogen infection under different scenarios regarding seasonality in vector natural infectivity (i.e. constant or increasing over the season) and grapevine recovery from infection (i.e. none or seasonal recovery). The extent to which local climatic conditions affect risk estimates via differences in vector abundance was investigated. Seasonal natural infectivity, seasonal recovery, and especially the combination, reduced (up to 8‐fold on average) within‐season and cumulative yearly estimates of pathogen spread. Estimated risk of infection also differed greatly among years due to large differences in vector abundance, with wet and moderate winter and spring conditions favouring higher G. atropunctata abundance. Seasonal variation of the pathogen–vector interaction may play an important role in the dynamics of disease in vineyards, reducing the potential prevalence from what it could be in their absence. Moreover, climate, by affecting sharpshooter leafhopper abundance or activity, may influence Pierce’s disease dynamics.  相似文献   

7.
A seasonal model, where a growing season is defined as the time between sowing and harvest and alternates with an inter-crop period, was derived to study the effects of the ‘cost of virulence’ and cropping ratio on durability of resistance. We assumed a single strain of virulent pathogen, a single strain of avirulent pathogen and two cultivars (one resistant and one susceptible) and studied two measures of durability of resistance (‘take-over time’ and ‘usefulness time’). Take-over time is defined as the time needed for the virulent strain of the pathogen to reach a preset threshold and predominate over the previous pathogen population. Usefulness time is the time needed before the estimated gain in green canopy area duration per plant through the use of the resistant cultivar becomes negligible. The model suggested that, although it could take several seasons before the virulent strain of the pathogen predominated over the previous pathogen population, the usefulness time of the resistant cultivar was always much shorter. Furthermore, increasing selection for the virulent strain of the pathogen (through increasing the cropping ratio of the resistant cultivar) caused the virulent strain of the pathogen to invade the system more rapidly. Cost of virulence, reflecting differences in pathogen infection rates between the four possible combinations of cultivar/pathogen strain, significantly affected durability of resistance, with the dynamics of the virulent and avirulent strains ranging from a case where the virulent strain of the pathogen died out to a case where the virulent strain of the pathogen invaded the resident pathogen population. An intermediate state, where the system reached equilibrium and the virulent strain of the pathogen neither became predominant nor died out, was defined as ‘coexistence’ of both strains of the pathogen. Occurrence of coexistence was directly related to the cost of virulence since it did not occur when virulence of the pathogen did not have a fitness cost. Two methods to include cost of virulence in the model gave similar results in relation to the two measures of durability of resistance studied.  相似文献   

8.
Pierce's disease (PD) of Vitis vinifera grapevines is caused by the bacterium Xylella fastidiosa, a pathogen with a wide plant host range. Exposure of X. fastidiosa-infected plant tissue to cold temperatures has been shown to be effective at eliminating the pathogen from some plant hosts such as grapevines. This "cold curing" phenomenon suggests itself as a potential method for disease management and perhaps control. We investigated cold therapy of PD-affected 'Pinot Noir' and 'Cabernet Sauvignon' grapevine. In the fall, inoculated plants and controls of each cultivar were transported to each of four field sites in California (Foresthill, McLaughlin, Hopland, and Davis) that differed in the magnitude of cold winter temperatures. A model for progression of the elimination of plant disease in relation to temperature was conceptualized to be a temperature-duration effect, where temperatures below a particular threshold kill X. fastidiosa with increasing efficacy as the temperature decreases to some value <6?C. The temperature effect was modeled as a likelihood of a particular temperature killing the pathogen and is termed the ?killing index?. We developed a mathematical model for cold curing of grapevines inoculated with X. fastidiosa and calibrated the model with cold-curing data collected in a field study. Parameter estimation resulted in lowest sum of squared differences across all 10 trials to be low temperature below which the organism is killed (T(0)) = 6°C, number of hours to achieve 100% cure (N(100)) = 195 h, number of hours to achieve 10% cure (N(10)) = 20 h, and killing index (K(x)) = 0.45 for Pinot Noir and T(0) = 6°C, N(100) = 302 h, N(10) = 170 h, and K(x) = 0.41 for Cabernet Sauvignon. With the parameter estimates optimized by model calibration, the simulation model was effective at predicting cold curing in four locations during the experiment, although there were some differences between Hopland for Pinot Noir and Davis for Cabernet Sauvignon. Using historical temperature data, the model accurately predicted the known severity of PD in other grape-growing regions of California, suggesting that it may have utility in assessing the relative risk of developing PD in proposed new vineyard sites.  相似文献   

9.
Fire blight is the most damaging bacterial disease in apple production worldwide. Cankers and symptomless infected shoots are known as sites for the overwintering of Erwinia amylovora, subsequently providing primary inoculum for infection in the spring. In the present work, further potential sources of inoculum were investigated. Real‐time PCR assays covering a 3‐year‐period classified 19·9% of samples taken from fruit mummies as positive. Bacterial abundance in fruit mummies during autumn, winter and spring was up to 109 cells per gram of tissue and correlated well with later infection rates of blossoms. Blossoms of non‐host plants growing close to infected trees were also shown to be colonized by E. amylovora and to enable epiphytic survival and propagation of bacteria. The results indicate a potential role of fruit mummies and buds in overwintering and as a source of primary inoculum for dissemination of the pathogen early in the growing season. Non‐host blossoms may also serve as an inoculum source in the build‐up of the pathogen population. Both aspects may contribute significantly to the epidemiology of E. amylovora. The significance of infected rootstocks as an inoculum source is also discussed. Fruit mummies might be used to determine pathogen pressure in an orchard before the beginning of the blooming period.  相似文献   

10.
Australian wheat consigned for export from Australian ports was surveyed in March 2004 using a national diagnostic protocol for detection and identification of Tilletia indica . No ustilospores of T. indica were detected, confirming previous surveys which have failed to detect T. indica in Australia. However, the survey detected moderate levels of the common smuts Tilletia caries (syn. Tilletia tritici ), Tilletia laevis and Urocystis agropyri , and very low levels (average fewer than six ustilospores per 150 g sample) of an unidentified dark, tuberculate-spored Tilletia in ≈ 60% of samples tested. Comparison with herbarium specimens enabled identification of the majority of the tuberculate ustilospores as Tilletia ehrhartae , a smut fungus known to infect only Ehrharta calycina (perennial veldt grass) and which is common in southern Australia. A smaller number of tuberculate smut ustilospores were identified as Tilletia walkeri , a smut of Lolium spp. recorded in Australia but apparently uncommon. Both T. ehrhartae and T. walkeri bear sufficient resemblance to T. indica for misidentifications to be possible where only a very few ustilospores are seen, although T. ehrhartae ustilospores are always <25  µ m in diameter. The frequent presence of ustilospores of both T. ehrhartae and T. walkeri as contaminants of Australian wheat grain exports has significance for diagnosticians testing Australian export wheat, as it demonstrates the potential for tuberculate ustilospores of species other than those covered in existing diagnostic protocols to be misidentified as T. indica . This paper describes T. ehrhartae in detail, and provides criteria for its differentiation from T. indica , T. walkeri and some other species.  相似文献   

11.
Anthracnose is the main disease of persimmon and is caused by Colletotrichum spp. The study of field epidemiology is essential for the development of efficient management of this disease. In this study, we investigated infection by Colletotrichum spp. throughout the persimmon growing season to understand the host–pathogen interactions better. We observed the production of primary inoculum of persimmon anthracnose and described how epidemics progress from secondary infections during the fruit crop season. The field study was carried out in an organic orchard with three susceptible persimmon cultivars, Fuyu, Kakimel and Jiro, for three consecutive seasons. Our results indicate that the pathogen survives in 1-year-old shoots, which are the sources of primary inoculum. Later that growing season, the inoculum reaches flowers and new shoots, developing symptoms and producing the secondary inoculum. Fruit drop was also observed, with or without symptoms of anthracnose, throughout the plant cycle. In some of the symptomless fruit, collected from the plant and from the ground where they had fallen, latent infections of Colletotrichum spp. were detected. Shoots, flowers, immature and ripened fruit remained infected throughout the growing season, producing conidia that could lead to new secondary infections within and among plants. The incidence of anthracnose in fruit at harvest and postharvest proved to be less relevant for disease management. Practices for chemical and cultural control of the disease throughout the persimmon growing season are discussed.  相似文献   

12.
Rhizoctonia solani and R. oryzae are the principal causal agents of Rhizoctonia root rot in dryland cereal production systems of the Pacific Northwest. To facilitate the identification and quantification of these pathogens in agricultural samples, we developed SYBR Green I-based real-time quantitative-polymerase chain reaction (Q-PCR) assays specific to internal transcribed spacers ITS1 and ITS2 of the nuclear ribosomal DNA of R. solani and R. oryzae. The assays were diagnostic for R. solani AG-2-1, AG-8, and AG-10, three genotypes of R. oryzae, and an AG-I-like binucleate Rhizoctonia species. Quantification was reproducible at or below a cycle threshold (Ct) of 33, or 2 to 10 fg of mycelial DNA from cultured fungi, 200 to 500 fg of pathogen DNA from root extracts, and 20 to 50 fg of pathogen DNA from soil extracts. However, pathogen DNA could be specifically detected in all types of extracts at about 100-fold below the quantification levels. Soils from Ritzville, WA, showing acute Rhizoctonia bare patch harbored 9.4 to 780 pg of R. solani AG-8 DNA per gram of soil.. Blastn, primer-template duplex stability, and phylogenetic analyses predicted that the Q-PCR assays will be diagnostic for isolates from Australia, Israel, Japan, and other countries.  相似文献   

13.
ABSTRACT Karnal bunt of wheat, caused by Tilletia indica, was found in regions of the southwestern United States in 1996. Yield losses due to Karnal bunt are slight, and the greatest threat of Karnal bunt to the U.S. wheat industry is the loss of its export market. Many countries either prohibit or restrict wheat imports from countries with Karnal bunt. In 1997, teliospores morphologically resembling T. indica were isolated from bunted ryegrass seeds and wheat seed washes. Previously developed PCR assays failed to differentiate T. indica from the recently discovered ryegrass pathogen, T. walkeri. The nucleotide sequence of a 2.3 kb region of mitochondrial DNA, previously amplified by PCR only from T. indica, was determined for three isolates of T. indica and three isolates of T. walkeri. There was greater than 99% identity within either the T. indica group or the T. walkeri group of isolates, whereas there was =3% divergence between isolates of these two Tilletia species. Five sets of PCR primers were made specific to T. indica, and three sets were designed specifically for T. walkeri based upon nucleotide differences within the mitochondrial DNA region. In addition, a 212 bp amplicon was developed as a target sequence in a fluorogenic 5' nuclease PCR assay using the TaqMan system for the detection and discrimination of T. indica and T. walkeri.  相似文献   

14.
The Linum marginale–Melampsora lini plant–pathogen interaction has been studied extensively with regard to its epidemiology and population genetic structure (host resistance and pathogen virulence) in a natural metapopulation. In this study, this system was used in an experimental metapopulation approach to investigate explicitly how the distance (degree of isolation) between local population patches influences disease dynamics within a growing season, as well as the genetic structure of pathogen populations through stochastic colonization and extinction processes. The experimental design centred on four replicate sets of populations, within which patches were spaced at increasingly greater distances apart. Each patch consisted of an identical set of host and pathogen genotypes, with each pathogen genotype having the ability to attack only one of four host-resistance types. Over the 2 years of the experiment, the results showed clear 'boom-and-bust' epidemic patterns, with the strongest determinant of disease dynamics within a growing season being the identity of particular host–pathogen genotypic combinations. However, there were also significant effects of spatial structure, in that more isolated patches tended to exhibit lower levels of disease during epidemic peaks than patches that were close together. Extinction of pathogen genotypes from individual populations was positively related to the severity of disease during preceding epidemic peaks, but negatively related to the level of disease present at the final census prior to overwintering. The probability of recolonization of pathotypes into populations during the second growing season was most strongly related to the distance to the nearest neighbouring source population in which a given pathotype was present. Overall, these results highlight the importance of spatial scale in influencing the numerical and genetical dynamics of pathogen populations.  相似文献   

15.
Brown spot disease on pear caused by Stemphylium vesicarium may affect leaves and fruits. Inoculum sources present on orchard floors play an important role in the epidemiology of pear brown spot. The pathogen can overwinter on plant residues and multiply and spread on the residues during the growing season. In the Netherlands, brown spot characteristically occurs only in a fraction of the orchards per season. Until now, no tools are available for Dutch pear growers to predict the risk of brown spot in specific orchards. As a consequence, preventive fungicide sprayings are common. The concentration of DNA of pear-pathogenic S. vesicarium was quantified by a specific TaqMan-PCR assay for various types of plant residues present on orchard floors to evaluate their importance as potential inoculum source. The pathogen was often found in residues of pear leaves, grasses and weeds, but only occasionally in mummies and prunings. Studies of the population dynamics showed that S. vesicarium decreased in dead pear leaves during early winter whereas pathogen populations developed with irregular pattern during the growing season on residues of weeds and grasses. Based on DNA concentrations of S. vesicarium in plant residue samples taken in 78 to 106 orchards in the springs of 2010, 2011 and 2012, the risk of brown spot development could be predicted for individual orchards. Such a risk prediction will allow growers to adapt their fungicide spray schedules to avoid unnecessary sprays in low-risk orchards.  相似文献   

16.
Insect reproduction may be affected by a number of factors including seasonal changes in larval or adult nutrition. The effect of season on the reproductive potential ofMonochamus galloprovincialis (Olivier) females reared inPinus sylvestris L. (Scots pine) logs was investigated by constructing fertility tables for each log that differed only in the season they were cut. Population parameters were compared among three seasonal cohorts. The intrinsic rate of increase and most of the associated population parameters of beetles that emerged from logs cut during spring were higher than for beetles emerged from summer and autumn logs. Slight differences were found between summer and autumn cohorts. We suggest that seasonal differences in the nutritional quality of logs caused differences inM. galloprovincialis survival and reproductive potential. http://www.phytoparasitica.org posting March 16, 2008.  相似文献   

17.
ABSTRACT The population structure of Heterobasidion annosum in the Pacific Northwest (PNW) Christmas tree plantations was estimated at two spatial scales to assess the relative importance of primary and secondary infection, colonization, and spread of the pathogen. Ninety-three isolates from single trees in 27 discrete mortality pockets and 104 isolates from 12 individual root systems of noble and Fraser fir trees were sampled near Mossyrock, Washington. Isolates were genotyped using somatic compatibility assays and microsatellite markers to determine the spatial scale at which dispersal of single genotypes (genets) was occurring. All isolates sampled from different trees in discrete mortality pockets had distinct genotypes, whereas the root systems of single trees were dominated by one or two genotypes. These results suggest that infection of PNW Christmas trees results from frequent primary infection events of adjacent stumps and localized secondary spread within root systems rather than clonal spread of the pathogen between adjacent trees. We hypothesize that mortality pockets may be due to availability of infection courts and/or variation in inoculum levels during selective harvesting of patches of mature trees.  相似文献   

18.
ABSTRACT Modeling techniques were developed to quantify the probability of Tilletia indica entering and establishing in Western Australia (WA), and to simulate spread, containment, and the economic impact of the pathogen. Entry of T. indica is most likely to occur through imports of bulk grain or fertilizer (0.023 +/- 0.017 entries per year and approximately 0.009 +/- 0.009 establishments per year). Entry may also occur through straw goods, new or second-hand agricultural machinery, and on personal effects of travelers who have visited regions with infected plants. The combined probability of entry and establishment of T. indica, for all pathways of entry, is about one entry every 25 years and one establishment every 67 years. Alternatively, sensitivity analysis does show that increases in quarantine funding can reduce the probability of entry to about one entry every 50 years and less than one establishment every 100 years. T. indica is spread efficiently through contaminated farm machinery, seed and soil, rain, air currents, and animals. Depending on the rate of spread of the pathogen and the amount of resources allocated for detection, the time until first detection could range from 4 to 11 years and the economic impact could range from 8 to 24% of the total value of wheat production in WA.  相似文献   

19.
ABSTRACT Leaf blotch, caused by Rhynchosporium secalis, was studied in a range of winter barley cultivars using a combination of traditional plant pathological techniques and newly developed multiplex and real-time polymerase chain reaction (PCR) assays. Using PCR, symptomless leaf blotch colonization was shown to occur throughout the growing season in the resistant winter barley cv. Leonie. The dynamics of colonization throughout the growing season were similar in both Leonie and Vertige, a susceptible cultivar. However, pathogen DNA levels were approximately 10-fold higher in the susceptible cultivar, which expressed symptoms throughout the growing season. Visual assessments and PCR also were used to determine levels of R. secalis colonization and infection in samples from a field experiment used to test a range of winter barley cultivars with different levels of leaf blotch resistance. The correlation between the PCR and visual assessment data was better at higher infection levels (R(2) = 0.81 for leaf samples with >0.3% disease). Although resistance ratings did not correlate well with levels of disease for all cultivars tested, low levels of infection were observed in the cultivar with the highest resistance rating and high levels of infection in the cultivar with the lowest resistance rating.  相似文献   

20.
The infection process of a Colletotrichum species causing latent infection and anthracnose in cowpea ( Vigna unguiculata ) was studied in seedlings by light and confocal microscopy. Leaf surfaces were extensively colonized by an anastomosing network of germ-tubes and conidia. This epiphytic mycelium produced abundant secondary conidia on short conidiophores. Although melanized appressoria were developed, the host surface was not penetrated directly. The fungus only gained ingress into leaves through stomatal openings, by means of undifferentiated germ-tubes, and slowly colonized the mesophyll by intercellular hyphae, without initially producing visible symptoms. Anthracnose lesions with multisetate acervuli appeared on senescent leaves after a prolonged symptomless period of host colonization lasting > 2 weeks. Analysis of the nucleotide sequences of the amplified D2 and ITS-2 regions of rDNA revealed close similarities (95–96%) between this cowpea pathogen and isolates of C . gloeosporioides from Aeschynomene virginica, Stylosanthes scabra and Mangifera indica. These results, in addition to other morphological and growth attributes, identify this endophytic anthracnose pathogen of cowpea as a Colletotrichum species distinct from C. capsici and C. destructivum .  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号