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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
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玉蜀黍赤霉的营养亲和性及其对多菌灵的抗性在菌丝融合过程中的遗传 总被引：4，自引：0，他引：4
利用硝酸盐营养缺陷突变体(nit)标记，对采自浙江、江苏、上海等地的33个玉蜀黍赤霉菌株的营养亲和性进行研究。结果发现，这些菌株分别属于30个不同的营养亲和群(VCG8)，表明中国玉蜀黍赤霉自然群体的遗传变异较大。用药剂驯化法获得了6株ZF43菌株的多菌灵(MBC)室内抗药突变体，并研究了其中2株抗药突变体的营养亲和性能。结果表明，玉蜀黍赤霉对多菌灵产生抗药性后不会改变其营养亲和性能。但发现在营养亲和的两菌株之间发生菌丝融合以后，不能或很少能进行细胞核遗传物质的交换和重组，因此，菌丝融合在该菌对多菌灵的抗药群体发展中的作用较小。 相似文献
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多菌灵是植物病害防治中常用的化学杀菌剂,野生型哈茨木霉对多菌灵比较敏感。为了能够更好地将哈茨木霉菌应用于实践,本试验采用紫外线-氯化锂复合诱变的方法,实现哈茨木霉菌株对多菌灵的抗性改良。试验共获得315株正向突变菌株,其中hcb-35菌株抗性能力较强。利用毒力测定方法检测了多菌灵对hcb-35有效抑菌中浓度,及hcb-35对多菌灵的抗药遗传稳定性;并利用对峙试验及显微观察检测其抑菌能力。结果显示,与哈茨木霉出发菌株hc相比,多菌灵对哈茨木霉突变株hcb-35菌株的有效抑菌中浓度提升285%;连续转接12代后,hcb-35菌株抗药性相对稳定且抑菌效果较出发菌株无明显差异,表明应用紫外-氯化锂复合诱变哈茨木霉可以获得遗传稳定的耐多菌灵突变株。 相似文献
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The effects of carbendazim on carbendazim-sensitive (wild-type) and -resistant strains of Fusarium graminearum and Botrytis cinerea were compared. When treated with carbendazim, conidia and germlings of wild-type F. graminearum and B. cinerea germinated and grew to produce stunted, distorted, and abnormally branched germlings; in addition, distinct nuclei were replaced by irregularly distributed chromosome masses, and normal nuclear division was not observed. The CMI (chromosome mitosis index) values of wild-type strains rapidly increased within 60 min of treatment with carbendazim and then rapidly declined. Whereas the wild-type strains of the two fungi responded similarly, the carbendazim-resistant strains of F. graminearum and B. cinerea responded differently to carbendazim. The resistant strain of F. graminearum showed normal mitosis but produced significantly more branches and higher CMI values when treated with carbendazim than when untreated. In contrast, the carbendazim-resistant strain of B. cinerea exhibited normal morphology and mitosis after carbendazim treatment. The results suggest that the mechanism for carbendazim resistance in F. graminearum differs from that in B. cinerea and other fungi. 相似文献
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