共查询到20条相似文献，搜索用时 31 毫秒
1.
Nuray Özer Temine Şabudak Cengiz Özer Katia Gindro Sylvain Schnee Erhan Solak 《Journal of General Plant Pathology》2017,83(5):316-328
Cuticular wax on the plant epidermis inhibits or enhances prepenetration events of powdery mildew (Erysiphe necator Schwein). We examined the role of cuticular leaf and berry waxes as a resistance mechanism in four grapevine genotypes (Italia?×?Mercan-174, Gürcü, Isabella, Özer Karas?) resistant to powdery mildew after natural infection and inoculation. To understand cuticular wax properties, we determined the amount of wax and antifungal effects of thin layer chromatography (TLC) fractions from cuticular leaf and berry waxes, then assessed the chemical composition of fractions with different antifungal activities using gas chromatography/mass spectrometry (GC/MS). Susceptible genotypes Cabernet Sauvignon and Italia were used for comparison. Resistant and sensitive genotypes did not differ significantly in the total amount of wax on leaves and berries; however, 27 fatty acids, 26 alkanes, 6 terpenes, 4 indole derivatives and 4 ketones, and 3 amides, 3 phenols and 3 steroids were detected in fractions with high antifungal activity (≥75% inhibition of germination) in leaf and/or berry cuticular waxes of resistant genotypes only. These compounds may be evaluated as markers for powdery mildew resistance during genotype selection in a grapevine breeding program. 相似文献
2.
ABSTRACT Grape berries are highly susceptible to powdery mildew 1 week after bloom but acquire ontogenic resistance 2 to 3 weeks later. We recently demonstrated that germinating conidia of the grape powdery mildew pathogen (Uncinula necator) cease development before penetration of the cuticle on older resistant berries. The mechanism that halts U. necator at that particular stage was not known. Several previous studies investigated potential host barriers or cell responses to powdery mildew in berries and leaves, but none included observation of the direct effect of these factors on pathogen development. We found that cuticle thickness increased with berry age, but that ingress by the pathogen halted before formation of a visible penetration pore. Cell wall thickness remained unchanged over the first 4 weeks after bloom, the time during which berries progressed from highly susceptible to nearly immune. Autofluorescent polyphenolic compounds accumulated at a higher frequency beneath appressoria on highly susceptible berries than on highly resistant berries; and oxidation of the above phenolics, indicated by cell discoloration, developed at a significantly higher frequency on susceptible berries. Beneath the first-formed appressoria of all germinated conidia, papillae occurred at a significantly higher frequency on 2- to 5-day-old berries than on 30- to 31-day-old fruit. The relatively few papillae observed on older berries were, in most cases (82.8 to 97.3%), found beneath appressoria of conidia that had failed to produce secondary hyphae. This contrasted with the more abundantly produced papillae on younger berries, where only 35.4 to 41.0% were located beneath appressoria of conidia that had failed to produce secondary hyphae. A pathogenesis-related gene (VvPR-1) was much more highly induced in susceptible berries than in resistant berries after inoculation with U. necator. In contrast, a germin-like protein (VvGLP3) was expressed within 16 h of inoculation in resistant, but not in susceptible berries. Our results suggest that several putative barriers to infection, i.e., cuticle and cell wall thickness, antimicrobial phenolics, and two previously described pathogenesis-related proteins, are not principal causes in halting pathogen ingress on ontogenically resistant berries, but rather that infection is halted by one or more of the following: (i) a preformed physical or biochemical barrier near the cuticle surface, or (ii) the rapid synthesis of an antifungal compound in older berries during the first few hours of the infection process. 相似文献
3.
ABSTRACT Grape berries become resistant to powdery mildew early in development and are nearly immune to infection within 4 weeks after bloom. In this study, ontogenic resistance did not reduce attachment, germination, or appressorium formation of Uncinula necator on 3- to 4-week-old berries of Vitis vinifera 'Chardonnay' or 3-week-old berries of V. labruscana 'Concord'. Pathogen ingress halted at the cuticle before formation of a penetration pore. As berries aged, hyphal elongation and colony growth slowed until finally no secondary hyphae formed on fully resistant berries. More appressoria formed per unit of hyphal length as berries aged, indicating that failure to penetrate older berries led to increased attempts to penetrate resistant fruit. Additionally, hyphae within the colonies began to die as berries aged. Finally, the number of degree-hours between germination and sporulation of the colony (latent period) increased and sporophore density decreased with berry age at time of inoculation. Thus, ontogenic resistance both slows, and eventually halts disease development on grape berries, and limits the likelihood of spread by reducing absolute supply of conidia and delaying their formation. It furthermore has a consistent, stable, and predictable impact on grape powdery mildew and operates in a similar fashion and to a similar degree in both V. labruscana and V. vinifera, although at a slightly earlier phenological stage in V. labruscana. 相似文献
4.
ABSTRACT Inflorescences of field-grown grapevines (Vitis vinifera L. cv. Gamay) were inoculated with a Botrytis cinerea conidia suspension or dried conidia at different stages during bloom in moist weather. Approximately 10% of the conidia germinated within 72 h, resulting in two to three times more latent infections than uninoculated controls in pea-size (7 mm in diameter) berries. In surface-sterilized pea-size berries, latent B. cinerea was present predominantly in the receptacle area. After veraison, latent B. cinerea also was found in the style and, in mature berries, latent colonies were distributed throughout the pulp. Inoculation at full bloom led to the highest disease severity (66%) at harvest, compared with 38% in controls. Stilbene stress metabolites in the flowers were measured by high-performance liquid chromatography. Resveratrol accumulated mainly after pre-bloom and full-bloom inoculation, but did not prevent infection. Piceid levels did not change following inoculation, while epsilon-viniferin was found in necrotic tissues only, and pterostilbene and alphaviniferin were not detected at all. B. cinerea conidia suspensions also were applied to various locations on flowers of pot-grown cvs. Pinot Noir and Chardonnay. Inoculation of the receptacle area, but not that of the stigma and ovary, resulted in latent infections. Stilbene synthesis was similar to the field results, with resveratrol accumulating mainly in the calyptra and receptacle area. Constitutive soluble phenolic compounds (mainly derivatives of quercetin and hydroxy-cinnamic acid) were present at high concentrations in the calyptra but at low levels in the receptacle area. These experiments confirmed bloom as a critical time for B. cinerea infection in grapes and suggest that the most likely site of infection is the receptacle area or cap scar exposed at anthesis. Stilbenes may have a limited role in inhibition of flower infection and latency in susceptible grape cultivars, and epsilon-viniferin may be a by-product rather than a deterrent of infection. 相似文献
5.
Thirteen apple cultivars and selections were evaluated in a greenhouse for their reaction to cedar-apple rust inoculation Five of the cultivars selections developed aecial lesions on their leaves whereas the sixth cultivar Jonathan, showed only pycnial lesions. The responses of the remaining seven resistant cultivars selections ranged from a lack of any visible symptoms to the presence of discrete flecks or continuous chlorotic mottles Quantitative parameters were used for statistical analysis; these included the highest number of pycnial lesions on a leaf/plant ( N ). the largest diameter of pycnial lesions on any leaf/plant (D)), and the calculated infection rating ( IR = ND ). Significant differences were observed among cultivars selections for variables N. D. and IR . Segregation ratios among progenies derived from 16 controlled crosses indicated that resistance to cedar-apple rust was conditioned by two major genes, and both were required in dominant form to confer resistance. However, in three crosses the dual-gene hypothesis was inadequate to explain the reaction of seedlings. 相似文献
6.
7.
The behaviour of Peronospora viciae was examined on four pea ( Pisum sativum ) cultivars (Maro, Superb, Victory Freezer and Surprise) which appeared to exhibit varying degrees of resistance to this pathogen. Penetration into all cultivars was similar and mainly by direct entry through the cuticle. The pathogen grew in a similar manner and at a similar rate in all the cultivars during the early stages (<96 h) of tissue colonization. As it approached the onset of sporulation its growth slowed down in the more resistant cultivars but in no instance were any hypersensitive or other host cell reactions observed. Greater differences between the cultivars were seen in the extent of sporulation, with the least resistant cultivar (Superb) bearing the largest number of sporangiospores. There was much less sporulation on the most resistant cultivar (Maro) and the process was more dependent on temperature than it was on Superb. The development of mature plant resistance occurred in a similar way and on a similar time-scale in all cultivars. The youngest leaflets on plants which were less than 8 weeks old at inoculation showed the least resistance to infection and colonization. 相似文献
8.
ABSTRACT Epicuticular wax on needles was evaluated for its influence on Cronartium ribicola infection of resistant and susceptible selections of Pinus strobus. Environmental scanning electron microscopy comparisons revealed that needles from a resistant selection of eastern white pine, P327, had a significantly higher percentage of stomata that were occluded with wax, fewer basidiospores germinating at 48 h after inoculation, and fewer germ tubes penetrating stomata than needles from a susceptible selection H111. In addition, needles from seedlings that failed to develop symptoms 6 weeks after inoculation, from a cross between P327 and susceptible parent H109, had a significantly higher percentage of stomata occluded with wax compared with needles from seedlings that developed symptoms. In experiments where epicuticular waxes were removed from needles before seedlings were infected, resistant seedlings without wax developed approximately the same number of infection spots (as measured by spot index) as susceptible seedlings with wax intact. Gas chromatography/mass spectrometry comparisons of extracted epicuticular waxes revealed several peaks that were specific to P327 and not found in susceptible H111 suggesting biochemical differences in wax composition. These results implicate the role of epicuticular waxes as a resistance mechanism in P. strobus selection P327 and suggest a role for waxes in reducing spore germination and subsequent infection through stomatal openings. 相似文献
9.
Assessment of the reaction of some spring barley cultivars to Pyrenophora teres using whole plants, detached leaves and toxin bioassay 总被引：1，自引：0，他引：1
H. S. S. SHARMA 《Plant pathology》1984,33(3):371-376
Twenty-one spring barley cultivars were tested for their reaction to Pyrenophora teres using three methods of assessment: inoculation of plants grown outdoors, a detached-leaf inoculation assay, and bioassay with P. teres toxins produced in vitro. Dram was the most resistant of the cultivars tested; a number of other cultivars including Goldmarker, Egmont and Georgie were also moderately resistant. Akka and Havila were highly susceptible. Good correlation was obtained between results from the three test methods. 相似文献
10.
黄瓜-酸黄瓜渐渗系霜霉病抗性及感病前后几种酶活性的变化 总被引：7，自引：0，他引：7
Using resistant and susceptible cultivars as controls, the resistant evaluation to Pseudoperonospora cubensis was carried out in 12 introgression lines from wide cross between cucumber(Cucumis sativus L.) and sour cucumber(Cucumis hystrix Chakr.). Three enzyme activities including POD, SOD and PAL were analyzed before and 7 d after inoculation, and the POD isozyme was detected by polyacrylamide electrophoresis. The inoculation results showed that, of the 12 accessions, 3 were identified as high resistant, 5 were moderately resistant and 4 were moderately susceptible to downy mildew. The enzyme activities of POD, SOD and PAL were greatly increased in resistant accessions after inoculation. PAL enzyme activities showed close correlation with disease rating before or after inoculation, which implicated that PAL enzyme activity might be used to estimate the resistance to downy mildew. POD isozyme electrophoresis showed that the number and intensity for the bands of resistant lines were significantly increased more than those of susceptible lines after inoculation. 相似文献
11.
Dinah M. Masaba H. A. H. Van Der Vossen 《European journal of plant pathology / European Foundation for Plant Pathology》1982,88(1):19-32
The histology of resistance to coffee berry disease (CBD) was studied in artificially inoculated berries and hypocotyls of 6-week old seedlings of a number of varieties ofCoffea arabica L. In resistant varieties a phellogen was quickly formed some cell layers below the site of infection and progress of the fungal invasion was effectively blocked by a complete barrier of suberized cells. Such barriers were absent or incompletely developed in CBD susceptible varieties. A highly significant correlation (r=0.87) was found between the frequencies of complete barrier formation in berries and in hypocotyls of young seedlings, while both were also highly correlated to observed mature plant resistance (r>-0.93). Resistance to CBD in arabica coffee may to an important extent be based on the formation of cork barriers. These cork barriers confine the pathogen to the small volume of tissue external to the barrier so that its growth is severely restricted. Such a resistance mechanism is likely to be stable (race-nonspecific). The almost identical response to infection observed in berries and hypocotyls provides further evidence that plants with resistance to CBD can be reliably preselected by the hypocotyl inoculation test. 相似文献
12.
玉米品种抗茎腐病鉴定 总被引：10，自引：0，他引：10
１９９１￣１９９５年采用自然发病和土壤接种方法鉴定了１５５０份玉米品种对茎腐病的抗病性,表现高抗的３９７份,中抗３０４份,中感３６４份,高感４８５份,经重复鉴定,筛选出７６份抗性稳定的自交系和杂交种。不同抗性品种用肿囊腐霉菌和串珠镰刀菌接种测定,抗性反应基本一致,人工接种比自然发病鉴定效果好,通过病圃自然发病初筛,人工土壤接处复选,可准确鉴定大量材料的抗病性。 相似文献
13.
Isolales of B. cinerea obtained directly from protected lettuce crops were either sensitive or moderately resistant to dicarboximides. Types with a high level of resistance to dicarboximides developed under laboratory conditions. Isolates with a high level of resistance grew poorly and sporulated feebly on cucumber cotyledons or lettuce leaves whereas growth and sporulation of moderately resistant isolates were only slightly poorer than of sensitive isolates. Moderately resistant isolates were stable in culture and there was no evidence that they produced mixtures of sensitive and resistant conidia. In polythene tunnel studies with mixed B. cineaea populations, in the absence of dicarboximides. no highly resistant isolates and only a small percentage of moderately resistant isolates were recovered. 相似文献
14.
ABSTRACT Vitis labruscana 'Concord' is a grape cultivar widely grown in the United States for processing into juice and other grape products. Concord grapes are sporadically but sometimes severely damaged by the grape powdery mildew pathogen, Uncinula necator. Although the foliage is often reported to be moderately resistant to powdery mildew, severe fruit infection occurs in some years. We observed the seasonal development of powdery mildew on leaves, rachises, and berries of unsprayed Concord grapevines. Inoculations of flower and fruit clusters revealed a brief period of berry susceptibility and a protracted period of rachis susceptibility. The rachis remained highly susceptible to infection, and the severity of rachis infection increased throughout the growing season until the rachis formed a periderm shortly before harvest. In contrast, berries were nearly immune to infection within 2 weeks after fruit set. Rachis and berry infections were detected before the disease was observed on foliage, and the incidence of rachis and berry infection often exceeded disease incidence observed on foliage until after fruit acquired substantial ontogenic resistance. Excellent control of fruit infection, and adequate control of leaf infection, was achieved by two fungicide applications targeted at the peak period of fruit susceptibility. Although Concord is thought to be moderately resistant to powdery mildew, the rachis is highly susceptible, and may be the avenue by which prebloom infections make their way onto the developing fruit. Late-season infection of the rachis neither spread to the fruit, nor did it cause fruit to drop prematurely, and may be of little economic consequence on fruit destined for processing. Although fruit of V. vinifera cultivars have been reported to remain susceptible to infection until berry sugar levels reach 8 to 15%, Concord fruit become nearly immune to infection nearly 6 weeks before this stage of development. Because powdery mildew does not become conspicuous on foliage until late summer, it is generally regarded as a late-season problem on Concord grapes, and previous management programs have reflected this belief. However, the greatest contribution to control of fruit infection is due to fungicides applied during the peak period of fruit susceptibility, from bloom until shortly after fruit set, long before the disease is observed on foliage. 相似文献
15.
ABSTRACT The induction of resistance to Botrytis cinerea in carrot roots by UV radiation, a possible means for controlling storage diseases, was compared with systemic resistance induced by inoculation with the pathogen. UV radiation did not have any systemic effect, and disease resistance was induced only in tissues directly exposed to the radiation. Although UV radiation induced a local accumulation of 6-methoxymellein (6-MM), inoculation with B. cinerea caused 6-MM to accumulate systemically, away from the inoculation site. Because of amounts near or higher than the ED(50) (50% effective dose) for inhibiting B. cinerea found in both UV-treated and preinoculated roots at the time of challenge, 6-MM could be involved in both types of resistance. Freshly harvested carrots had a number of constitutive chitinases and beta-1,3-glucanases, which were not affected by UV radiation or inoculation. When challenged with B. cinerea, the induction of a 24-kDa chitinase was enhanced in UV-treated and preinoculated roots. Again, UV radiation had only a local effect in priming this chitinase response. Although UV- and pathogen-induced resistance in carrot may involve the same defenses, the responses are probably mediated differently, because UV radiation has an essentially local effect. 相似文献
16.
The aggressiveness of 20 Northern Ireland single-lesion isolates of Phytophthora infestans was compared following their inoculation onto detached leaflets of three potato cultivars chosen on the basis of their differing levels of race-nonspecific resistance to late blight: Bintje (highly susceptible); Cara (moderately resistant); and Stirling (more resistant). Five isolates from outside Northern Ireland were included for comparative purposes: two from the Republic of Ireland; two from the USA (representing the US-1 and US-8 clonal lineages); and one from Mexico. To control the variation between tests, a balanced incomplete block design was used, as opposed to either a complete block design or the method of inclusion of standard isolates, where such variation would have increased the error. Highly significant variation for disease parameters, including latent period, infection frequency, area under the lesion expansion curve (AULEC) and sporulation capacity, was found between isolates. These differences were much more marked on the cultivars exhibiting higher levels of race-nonspecific resistance. There was a significant interaction between isolate and cultivar for all parameters assessed and, overall, no one isolate was the most aggressive across all three potato cultivars. However, a group comprising seven of the 20 Northern Ireland isolates was consistently found to exhibit the highest levels of aggression towards all three cultivars for each of the disease parameters. These results demonstrate that significant variation for foliar aggressiveness exists within the Northern Ireland population of P. infestans , and indicate the importance of selecting appropriately aggressive isolates for evaluation of host resistance to late blight within breeding programmes. 相似文献
17.
Soil drench and stem puncture inoculation were compared as methods for selecting cocoa cultivars with resistance to Verticillium dahliae. Disease progress was more rapid and induced symptoms were more severe following stem puncture and, under glasshouse conditions, differences between cultivars were detected 15 days after inoculation. Moreover, using stem puncture, inoculum densities of 104 conidia/ml were sufficient to differentiate resistant and susceptible cultivars, whereas with the soil drench method, inoculum densities of 107 conidia/ml were necessary. Although a substantially higher proportion of plants were affected by stem puncture inoculation, the resistance of cultivar Pound-7 remained effective at high inoculum densities of 108 conidia/ml. With either method, older seedlings were more susceptible to V. dahliae than younger ones. However, with stem puncture, 15-day-old seedlings were sufficiently susceptible for a valid disease assessment. In contrast, with soil inoculation, 60-day-old plants were required. In a nursery trial with 15-day-old seedlings, seven cocoa genotypes previously selected as resistant, moderately resistant or susceptible to Verticillium dahliae , on the basis of root inoculation, were ranked in the same order when stem punctured. Stem puncture inoculation of young seedlings is cost-effective in terms of time and space, and is therefore recommended for screening of cocoa for wilt resistance, especially in large-scale breeding programmes. 相似文献
18.
Gadoury DM Seem RC Wilcox WF Henick-Kling T Conterno L Day A Ficke A 《Phytopathology》2007,97(10):1356-1365
ABSTRACT Production of grape (principally cultivars of Vitis vinifera) for high-quality wines requires a high level of suppression of powdery mildew (Uncinula necator syn. Erysiphe necator). Severe infection of either fruit or foliage has well-documented and deleterious effects upon crop and wine quality. We found that berries nearly immune to infection by U. necator due to the development of ontogenic resistance may still support diffuse and inconspicuous mildew colonies when inoculated approximately 3 weeks post-bloom. Fruit with diffuse mildew colonies appear to be healthy and free of powdery mildew in late-season vineyard assessments with the naked eye. Nonetheless, presence of these colonies on berries was associated with (i) elevated populations of spoilage microorganisms; (ii) increased evolution of volatile ethyl acetate, acetic acid, and ethanol; (iii) increased infestation by insects known to be attracted to the aforementioned volatiles; (iv) increased rotting by Botrytis cinerea; and (v) increased frequency of perceived defects in wines prepared from fruit supporting diffuse powdery mildew colonies. Prevention of diffuse infection requires extending fungicidal protection until fruit are fully resistant to infection. Despite a perceived lack of improvement in disease control due to the insidious nature of diffuse powdery mildew, potential deleterious effects upon crop and wine quality thereby would be avoided. 相似文献
19.
A radioimmunosorbent assay was developed for Botrytis cinerea which can be used to detect as little as 100 ng of Botrytis mycelium (dry weight). Of 22 fungi tested in the assay, all significant reaction was restricted to members of the Sclerotiniaceae. No reaction was obtained with representative isolates of Aspergillus, Alternaria or Peiticillium. Other Botrytis species gave the most reaction relative to B. cinerea. and related genera such as Monilinia and Sclerotinia yielded small reactions. The assay can be used to detect fi. cinerea infection of grape berries when as little as 0.1 % of homogenate from infected fruit is mixed with homogenate from sound fruit to simulate a minor infection. The assay of free run juice from various lots of grapes was highly correlated with visual assessments of infection in the field. Pursuant to various theories concerning bloom time infection, the assay was used to analyse the B. cinerea content of immature berry tips and floral debris; however, no evidence of such colonization was obtained. 相似文献
20.
A. Kerssies H. D. Frinking 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(3):257-263
Studies were conducted on the effects of seasonal levels of relative humidity, temperature, and total radiation, on dry weight of petals, on fresh weight of epicuticular wax and of cuticle of petals, on numbers ofBotrytis cinerea lesions in petals, and on preharvest flowering periods in gerbera and rose. No temporal relationships or significant correlations were found among dry weight of petals, weight of wax and cuticle of petals, and numbers of lesions on the petals. Temperature, relative humidity and total radiation did not correlate significantly with dry weight of petals, or with fresh weights of wax and cuticle of petals, except for a positive correlation between relative humidity and cuticle weight in the gerbera cultivar Delphi. No relation was found between weight of epicuticular wax and cuticle of petals and susceptibility of gerbera and rose petals toB. cinerea. The thickness of wax and cuticle on flowers did not seem to be an important factor influencing the susceptibility of flowers toB. cinerea. The seasonal pattern in number of lesions produced on the flowers byB. cinerea was related to the effects of relative humidity and radiation on infectivity of conidia of the pathogen on the flower surface but not to the effects on the susceptibility of flowers. 相似文献