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51.
lori INOUE Toshiaki OHARA Fumio NAMIKI Takashi TSUGE 《Journal of General Plant Pathology》2001,67(3):191-199
Restriction enzyme-mediated integration (REMI) mutagenesis was used to isolate mutants of Fusarium oxysporum f. sp. melonis impaired in pathogenicity. The race 2 strain Mel02010 was transformed with linearized pSH75, conferring resistance to hygromycin
B, with or without the enzyme used to linearize the plasmid. Addition of restriction enzymes did not affect the transformation
frequency. A total of 2929 REMI transformants were tested for pathogenicity to three melon cultivars, Amus, Ogon 9 and Ohi.
The race 2 strains are pathogenic to Amus and Ogon 9, but not to Ohi. Of 43 transformants with reduced pathogenicity on susceptible
melon cultivars, 12 mutants were examined in detail for pathogenicity, vegetative growth and integrative mode of pSH75. The
levels of pathogenicity varied among these mutants. Two mutants (B48 and B137) almost completely lost pathogenicity to both
susceptible cultivars, and the others had reduced pathogenicity. Mutants B48, B241, B886 and X36 were also impaired in vegetative
growth. Mutant B809 was a biotin auxotroph. By DNA gel blot analysis, nine mutants were found to contain a single copy of
the transformation vector. These mutants may thus be useful in isolating genes involved in pathogenicity.
Received 22 December 2000/ Accepted in revised form 16 April 2001 相似文献
52.
L. Daroda K. Hahn D. Pashkoulov E. Benvenuto 《Physiological and Molecular Plant Pathology》2001,59(6):317
The activation of Fusarium moniliforme endopolygalacturonase (endoPG) was studied during infection of maize plants. EndoPG is a plant cell wall degrading enzyme that cleaves the pectin component causing cell death. The authors generated several hybridoma cell lines producing endoPG specific monoclonal antibodies. One monoclonal antibody was selected and successfully used in Western blotting analysis to detect F. moniliforme endoPG secretion in vitro and in planta. Two F. moniliforme strains (FC-l0 and 62264) were used for the studies. Both strains revealed the expression of a single endoPG in vitro as in planta. EndoPG from strain FC-10 presented four isoforms whereas only two isoforms were revealed in the endoPG from strain 62264. Differences were also found in the sequences of the two endoPG genes indicating the presence of endoPG variability among F. moniliforme strains. 相似文献
53.
Carbendazim-resistant (RS) and control (CS) strains ofFusarium sporotrichioides Sherb., previously developed in our laboratory, were exposed to graded concentrations of azoxystrob in in broth media under
shake-culture conditions for 2, 3, 4 and 8 days. Azoxystrobin concentrations were 0, 1, 10 and 100 mg 1-1 broth and cultures were incubated at a constant 25°C. Mycelial growth was significantly affected by strain (P<0.01), azoxystrobin
concentration (P<0.001) and incubation time (P<0.001). Combined results for the four incubation times showed that CS yielded
higher mycelial mass than RS (P<0.01) only in the absence of azoxystrobin. At fungicide additions of 1, 10 and 100 mg P-1 mycelial growth was reduced (P<0.001) with minimal strain differences (P>0.05) at all three doses of azoxystrobin. Significant
(P<0.05 or better) strain-fungicide interactions were recorded in trichothecene production following exposure to azoxystrobin.
At 4 and 8 days of incubation, the 10 mg 1-1 addition of azoxystrobin stimulated T-2 toxin synthesis (P<0.05) only in RS cultures. In contrast, T-2 toxin enhancement
in CS cultures occurred only on day 8 but at a lower level of azoxystrobin (1 mg1-1). Thus, the stimulation of T-2 toxin synthesis depended upon strain and azoxystrobin level. Production of diocetoxyscirpenol
(DAS) was affected by a more complex set of interactions. Overall means showed that, in comparison with initial values (on
day 2 or 3), DAS output maximized significantly(P<0.05) on day 4 in RS cultures and on day 8 in CS. Marked strain effects were observed on exposure to the 10 mg 1-1 level of azoxystrobin. At this level, DAS production was enhanced in RS only after 4 (P<0.01 ) and 8 (P<0.05) days of incubation,
while in contrast, CS reduced DAS production. As with T-2 toxin, DAS production in CS was stimulated (P<0.05 or better) only
at low exposure levels of azoxystrobin. In the case of neosolaniol (NEO), however, the main effect of strain was significant
(P<0.05), with CS producing consistently more of the mycotoxin than RS on day 4 of the experiment. At this point, the NEO:T-2
toxin ratio was also higher in CS (0.63) than in RS (0.12), a feature reported by us previously. In conclusion, the present
investigation has shown for the first time that the development of resistance to one fungicide can affect trichothecene production
inF. sporotrichioides on exposure to a second fungicide. These results have been incorporated into a new classification scheme for fungicide efficacy
which is also presented in this paper.
http://www.phytoparasitica.org posting Oct. 7,2001. 相似文献
54.
Dry fungal biomass ofPenicillium chrysogenum (dry mycelium), a waste product of the pharmaceutical industry, was extracted with water and applied to the roots of melon
plants before or after inoculation withFusarium oxysporum f.sp.melonis (Font). Seedlings (4–6 days after emergence) treated with either acidic dry mycelium extract (DME) or neutralized dry mycelium extract
(NDME) were protected against challenge infection withFom. A single drench with 2–5% DME applied 12–72 h before inoculation provided significant control of the disease compared with
water-drenched, challenged seedlings. No protection was seen in plants treated 0–6 h before inoculation or 0–48 h after inoculation.
Neither DME nor NDME (0.5–5%) had any effect on fungal growthin vitro, which implied that disease controlin vivo was mediated by induced resistance. The resistance induced by DME protected melon plants not only against race 1,2, but also
against the three other races of the pathogen, indicating a race-non-specific resistance againstFom. Both DME and NDME significantly increased peroxidase activity and free L-proline content in seedlings 12 h and 48 h after
soil drench, respectively. Resistance to Fusarium wilt was significantly associated with elevated levels of peroxidase activity
but not with free L-proline content. Thus, peroxidase might be involved in the defense mechanisms activated by DME or NDME.
http://www.phytoparasitica.org posting Aug. 31, 2001. 相似文献
55.
禾谷镰孢菌对多菌灵的敏感性基线及抗药性菌株生物学性质研究 总被引:48,自引:5,他引:48
引起小麦赤霉病的禾谷镰孢菌(Fusarium graminearum)在华东地区对多菌灵已出现了高水平抗药性。本文报道了F.graminearum对多菌灵的敏感性基线及其抗药性菌株生物学特性。离体条件下多菌灵对100个野生敏感型菌株的平均EC50和MIC值分别为0.5748±0.0133 μg/ml和 < 1.4μg/ml。而对50个抗药性菌株的平均EC50和MIC值则分别为9.2375μg/ml和 > 100 μg/ml。在麦穗上多菌灵对50个敏感菌株和抗药性菌株防效的平均EC50分别为282.6 μg/ml和 > 2 000μg/ml。从田间获得的抗多菌灵菌株对苯菌灵、噻菌灵、甲基托布津表现交互抗药性,但不同于室内突变菌株,对乙霉威不表现负交互抗药性。抗药性菌株的无性和有性繁殖后代以及在无药培养基上菌丝体转代培养后,抗药水平保持不变。抗药性菌株的菌丝生长速率、产孢能力及致病力等与敏感菌株相比没有差异。 相似文献
56.
G. F. Kalc Wright D. I. Guest D. L. S. Wimalajeewa R. van Heeswijck 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(5):451-457
Isolates ofF. oxysporum collected from symptomless carnation cuttings from Australian carnation growers properties, together with isolates from national collections, were screened for pathogenicity and grouped according to vegetative compatibility and random amplified polymorphic DNA (RAPD) patterns. The collection of 82 Australian isolates sorted into 23 different vegetative compatibility groups (VCGs). Of 69 isolates tested for pathogenicity, 24 were pathogenic to carnations, while the remaining 45 were non-pathogenic. All pathogenic isolates were within two VCGs, one of which was also compatible with an isolate obtained from an international culture collection, and which is known to represent VCG 0021 and race 2. Race status of the two pathogenic VCGs remains unknown. The RAPD assay revealed distinct DNA banding patterns which could distinguish pathogenic from non-pathogenic isolates as well as differentiate between isolates from the two pathogenic VCGs. 相似文献
57.
以1μg/g土的氟乐灵播前土壤处理,棉花出苗后移栽到无氟乐灵的土壤中并接种棉花枯萎病菌(Fusarium axysporum f.sp.vasinfectum)。结果表明氟乐灵处理明显降低了棉苗枯萎病的株发病率和病情指数,提高了棉苗对枯萎病的抗病性。氟乐灵处理组棉苗根部和茎部枯萎病菌侵染率均低于对照组,特别是上部茎片段中处理组侵染率降低更为明显。氟乐灵处理组棉苗根部和茎部的菌量明显降低,而且处理组茎部菌量的增长明显滞后于对照。以上结果表明,病菌对氟乐灵处理棉苗根部的侵入和病菌在棉苗体内的纵向扩展及增殖受到了阻抑,因而氟乐灵处理后棉苗对枯萎病菌的抗性表现了抗侵入和抗扩展的特性。试验还证明,氟乐灵处理并接种病菌的棉苗茎部组织中类萜烯醛的含量明显提高;并产生一种能抑制病菌大型分生孢子萌发的真菌毒性物质。这些抑菌物质的产生和积累可能与抗扩展特性有关。 相似文献
58.
59.
Leah Tsror A. Nachmias Orly Erlich M. Aharon M. C. M. Pérombelon 《Phytoparasitica》1993,21(4):321-328
Potato seed tubers are imported annually to Israel from northern Europe. Although the seed is registered as certified, a survey
carried out over a 9-year period indicated that most lots were affected by latent or active bacterial and fungal infections.
Latent infection byErwinia carotovora subsp.atroseptica, the causal agent of blackleg, at a level of 103 cells/g peel, was present in 30% of the lots in most years. Black scurf caused byRhizoctonia solani was present in 20–70% of the imported lots, with a moderate to high level of infection in all years except 1985. In contrast,
although many lots were affected by powdery scab, common scab, and Fusarium dry rot in most years, disease incidence within
lots was generally low. The gangrene pathogen (Phoma exigua) was rarely detected. The survey findings are of marked importance, due to the extensive use of soil fumigation in Israeli
agriculture. 相似文献
60.