赣南脐橙绿霉病菌对常用杀菌剂抗性监测

 本文研究了来自赣南7个县的柑橘绿霉病菌(Penicillium digitatum)种群对该地区常用杀菌剂抑霉唑、咪鲜胺、甲基硫菌灵和百可得的抗性频率、抗性水平和对抑霉唑的抗性分子机制。结果表明:病菌对抑霉唑和咪鲜胺存在基本一致的抗性;2011和2012年病菌种群对抑霉唑和咪鲜胺的抗性频率分别为82%和90%,平均抗性倍数为51.5倍,抗性分子机制均属于IMZ-R3,即CYP51B基因启动子区发生199 bp插入的突变;病菌种群对甲基硫菌灵的抗性频率分别为82%和91%;病菌种群对百可得均表现敏感。本研究为采后柑橘病害防治药剂选择提供了科学的依据。     

浙江衢州地区柑橘绿霉病菌对抑霉唑和多菌灵的抗性水平及其分子机制

研究了采自浙江衢州地区,包括柯城区、衢江区和开化县12个贮藏库的70个柑橘绿霉病菌Penicillium digitatum菌株对抑霉唑和多菌灵的抗性频率、抗性水平及其抗性分子机制。结果表明:柯城区和衢江区的抑霉唑抗性菌株(最低抑制浓度MIC≥0.5 μg/mL)的比例分别为77.1%和62.5%,两地抗性菌株的平均EC50值分别为2.07±1.04 μg/mL和2.35±0.73 μg/mL,分别是当地敏感菌株EC50值的41.4和47.0倍;而采自开化县的菌株均对抑霉唑敏感(MIC≤0.1 μg/mL),平均EC50值为0.04±0.02 μg/mL。柯城区和衢江区的多菌灵抗性菌株(MIC≥10 μg/mL) 的比例分别为54.3%和54.2%,而开化县的抗性菌株比例仅为9.1%。即来自柯城和衢江两个柑橘主产区的绿霉病菌群体对抑霉唑和多菌灵的抗性频率均远高于非柑橘主产区的开化县群体,说明抗药性群体的形成与药剂使用历史有关。进一步研究发现,衢州地区柑橘绿霉病菌对抑霉唑的抗性均属于IMZ-R3型,即与抑霉唑靶标基因 CYP51B 启动子区的插入突变有关,而对多菌灵的抗性则与 β-微管蛋白基因的992位核苷酸点突变(T→A)导致对应的200位点的氨基酸突变(F→Y)有关。     

Real-time PCR法定量检测柑橘绿霉病菌对抑霉唑的抗性频率

 抑霉唑被广泛用来防治由指状青霉菌(Penicillium digitatum)引起的柑橘绿霉病。已有研究表明,柑橘绿霉病菌对抑霉唑的抗性由CYP51基因启动子区5个126-bp转录增强子的简单串联重复和126-bp转录增强子上199-bp的特异性片段插入所引起。基于这2种抗性分子机制,通过设计特异引物和优化条件,建立real-time PCR高通量分子检测技术,用于快速检测柑橘包装贮藏库中绿霉病菌群体对抑霉唑的抗性频率F_R,指导科学用药。     

浙江省柑橘绿霉病菌对嘧菌酯的敏感性研究

采用孢子萌发法和生长速率法测定了2000~2006年间采自浙江衢州、杭州、金华、丽水的65个柑橘绿霉病病菌Penicillium digitatum菌株对嘧菌酯的敏感性。结果表明:嘧菌酯对供试菌株 孢子萌发和菌丝生长的EC50值均呈单峰分布,分别介于0.020 1 ~0.260 0 μg/mL和0.005 3 ~0.079 4 μg/mL 之间,平均值分别为0.042 6 μg/mL 和0.025 0 μg/mL。敏感性频次分析结果表明,该65个菌株孢子萌发和菌丝生长对嘧菌酯的敏感性频率分布均符合正态分布,其EC50平均值0.042 6±0.030 4 μg/mL 和0.025 0±0.012 9 μg/mL可分别作为柑橘绿霉病菌孢子萌发和菌丝生长对嘧菌酯的敏感基线。     

Accumulation of SBI fungicides in wild-type and fenarimol-resistant isolates of Penicillium italicum

Fenarimol-resistant laboratory isolates of Penicillium italicum exhibit a high degree of cross-resistance to triazoles, a low degree of cross-resistance to imazalil and a low degree of negatively-correlated cross-resistance to morpholines. The cross-resistance to triazoles is ascribed to a differential accumulation level of these SBI fungicides in wild-type and fenarimol-resistant isolates. As in the case of fenarimol, the relatively low accumulation level of triazoles in resistant isolates is probably caused by the operation of a constitutive, energy-dependent efflux from mycelium, which hinders the triazoles from reaching their site of action in sterol biosynthesis. The accumulation level of imazalil and morpholines did not differ among wild-type and fenarimol-resistant isolates. This may be related to the fact that these fungicides at physiological pHs occur in a protonated form. The lack of a differential accumulation level can be the reason for the deviating cross-resistance patterns of these fungicides.     

柑橘内生燕麦镰刀菌Gds-1对柑橘青霉病的防治研究

柑橘青霉病是柑橘果实采后危害最大的病害。为得到一株可有效应用于柑橘青霉病防治的柑橘内生真菌菌株,进行了柑橘果实内生菌分离、离体与活体试验筛选、菌株形态学与多基因位点分子系统发育鉴定、菌株活体应用效果与作用特点以及菌株代谢产物稳定性与应用防效试验。结果表明:筛选所得的柑橘内生真菌Gds-1在离体与活体条件下均对柑橘青霉菌有较好的抑制效果;经多基因位点联合系统发育分析,将Gds-1鉴定为燕麦镰刀菌Fusarium avenaceum;提前48 h施用Gds-1菌体,对柑橘青霉病的预防效果最好 (防治效果为90.67%);Gds-1菌丝不会损害健康柑橘果实表皮,但可以在柑橘果实表皮伤口和被柑橘青霉菌感染的组织部位发挥作用,从而抑制柑橘青霉菌;当温度在 ?80~100 ℃和pH=5~10时,Gds-1无菌发酵液对柑橘青霉菌的拮抗作用高效稳定;单独施用Gds-1无菌发酵滤液28 d和56 d时,对柑橘青霉病的防效与100 μg/mL的抑霉唑相当,显著高于清水对照。本研究首次报道了生防镰刀菌F. avenaceum Gds-1对柑橘青霉病的防治作用,为柑橘果实采后生物源防腐剂的选择提供了新来源,为镰刀菌生物防治机理研究提供了新思路。     

Characterization of genetic and biochemical mechanisms of fludioxonil and pyrimethanil resistance in field isolates of Penicillium digitatum

Genetic and biochemical mechanisms of fludioxonil and pyrimethanil resistance in isolates of Penicillium digitatum were evaluated and compared to those characterized in other fungi. Resistant isolates were naturally occurring in packinghouses and were not associated with crop losses. For the phenylpyrrole fludioxonil, EC50 values were 0.02 to 0.04 microg/ml for sensitive, 0.08 to 0.65 microg/ml for moderately resistant (MR), and > 40 microg/ml for highly resistant (HR) isolates. Two fludioxonil-sensitive isolates evaluated were also significantly more sensitive to the unrelated dicarboximide fungicide iprodione, that also disrupts osmotic regulation, than the MR and HR isolates. There was no consistent relationship, however, between the HR and MR isolates and their sensitivity to iprodione or osmotic stress. Although, two nucleotide substitutions were found in a sequence analysis of the N-terminal amino acid repeat region of the os-1-related histidine kinase gene among isolates of P. digitatum, these were not correlated with fludioxonil resistance. In mycelia not exposed to fludioxonil, the amount of phosphorylated OS-2-related protein (PdOS-2) was higher in fludioxonil-sensitive isolates and lowest in the HR isolate. An increase in PdOS-2 was observed for sensitive and resistant isolates after exposure to fludioxonil. In addition, glycerol content in untreated mycelia of the fludioxonil-sensitive isolate was significantly higher than in resistant isolates. After exposure to fludioxonil, glycerol concentrations significantly increased in the sensitive and MR isolates, but not in the HR isolate. Thus, our studies indicate that the mode of action of fludioxonil in P. digitatum is probably the mitogen-activated protein kinase pathway that stimulates glycerol synthesis in sensitive and MR isolates. The general suppression of this pathway in resistant isolates was supported by the fact that growth and sporulation of MR and HR isolates were significantly reduced from that of sensitive isolates. In studies on the mode of action of anilinopyrimidines (AP), EC50 values for mycelial growth of P. digitatum and the previously characterized Botrytis cinerea were determined for cyprodinil and pyrimethanil using a defined culture medium without and with the addition of selected amino acids and homocysteine. The addition of amino acids resulted in a reduced toxicity of the two AP fungicides in both fungi, but the effect of each additive was significantly lower for P. digitatum than for B. cinerea. This suggests that methionine biosynthesis is not the primary target site of APs in P. digitatum.     

FRAC METHODS FOR MONITORING FUNGICIDE RESISTANCE

Methods are presented for monitoring fungicide sensitivity in a range of fungal pathogens ( Botrytis cinerea, Cercospora beticola, Cercosporidium personatum, Erysiphe graminis, Leptosphaeria nodorum, Monilinia fructicola, Mycosphaerella fijiensis, Penicillium digitatum and P. italicum, Pseudocercosporeila herpotrichoides, Puccinia recondita, Pyrenophora teres, Rhynchosporium secalis, Uncinula necator, Venturia inaequalis ). Three groups of fungicides are covered—sterol demethylation inhibitors (DMI), benzimidazoles and dicarboximides. The methods, developed by the sub-committees of FRAC, are intended for practical use in the implementation of resistance-avoiding strategies. Methods for phenylamide fungicides are in preparation and will be published later.     

The occurrence of thiabendazole-resistant isolates of Polyscytalum pustulans and Helminthosporium solani on seed potato tubers in relation to fungicide treatment and storage

Tubers infected with thiabendazole-sensitive isolates of Polyscytalum pustulans and Helminthosporium solani were treated annually for 4 years with benomyl, thiabendazole or a formulated mixture of thiabendazole and imazalil, and grown at three farms in Scotland. The proportion of thiabendazole-resistant isolates of H. solani increased, and isolates producing black colonies became more common with successive annual applications of thiabendazole or benomyl. Silver scurf was not reduced after three annual applications. When these fungicides were applied once to untreated seed the incidence of resistant isolates of H. solani was much less in 1988 than in 1991 when tubers had been grown on farms for 3 years from untreated seed.
The proportion of resistant isolates of P. pustulans increased with the number of successive applications of thiabendazole or benomyl but at differing rates on each farm. At one farm, skin spot was not reduced by three annual applications of these fungicides whereas at the other farms it was reduced by 90–100% by four annual applications.
A smaller proportion of resistant isolates of P. pustulans and H. solani was obtained after applying the mixture of thiabendazole and imazalil than after benomyl or thiabendazole alone. Their occurrence was not related to the number of fungicide applications. The mixture also reduced both diseases by more than 75% over the 4 years.
At one farm where resistant isolates of H. solani were present, tubers were infected when stored on trays but not when stored in bags.     

Characterization of Phytophthora spp. Causing Outbreaks of Citrus Brown Rot in Florida

ABSTRACT Epidemics of citrus brown rot from 1994 to 1997 in the south-central and east-coast citrus areas of Florida were characterized and the causal Phytophthora spp. identified. Two species of Phytophthora, P. palmivora and P. nicotianae, were consistently associated with brown rot. Epidemics caused by P. palmivora appeared to be initiated on immature fruit dropped on the orchard floor. The soilborne fungus infected and sporulated on these fruit and was then disseminated to fruit above 1 m in the canopy. In contrast, infection by P. nicotianae, the common cause of root rot, was confined to the lowest 1 m of the canopy. Fruit infected by P. palmivora produced large amounts of ellipsoidal sporangia available for splash dispersal, whereas those infected by P. nicotianae produced far fewer spherical sporangia. Isolates from brown rot epidemics were compared with P. nicotianae from citrus in Florida and Texas, P. citrophthora in California, P. palmivora, and selected Phytophthora spp. from other hosts. Brown rot symptoms produced by the different pathogenic citrus isolates on inoculated fruit were indistinguishable. Morphology, mating behavior, and isozyme patterns of brown rot isolates from 1988 to 1997 matched P. palmivora from citrus roots, other host plants, and other locations, but were different from characterized isolates of P. citrophthora in California and P. nicotianae in Florida and Texas. Cellulose acetate electrophoresis of the isozyme glucose-6-phosphate isomerase rapidly identified the causal citrus pathogen from infected fruit and soil isolation plates. Although P. palmivora is an aggressive pathogen of citrus roots, bark, and fruit, populations in orchard soils were low compared with P. nicotianae.     

Analysis of Colletotrichum musae populations from Brazil reveals the presence of isolates with high competitive ability and reduced sensitivity to postharvest fungicides

In this study, the sensitivity of 218 isolates of Colletotrichum musae to imazalil and thiabendazole was evaluated, as well the fitness and competitive ability of less sensitive isolates. There was a positive correlation between the sensitivity to the two fungicides, but the isolates were more sensitive to imazalil. The estimated effective concentration of the fungicide able to inhibit mycelial growth by 50% (EC₅₀) was used to select four isolates with the lowest and the highest values for both fungicides, which were considered as sensitive (S) and less sensitive (LS), respectively. The level of sensitivity was maintained after 10 successive transfers on fungicide-free medium. Both fungicides were effective in controlling the disease caused by S isolates of C. musae in detached banana fruit when recommended doses were used. However, only imazalil was able to control the disease caused by LS isolates. For both fungicides, analysis of fitness-related variables (mycelial growth, sporulation, germination, and virulence) showed no difference between the groups of S and LS isolates, but a large variation was observed within the group. The LS isolates to thiabendazole that showed a mutation (F200Y) in the β-tubulin gene did not have fitness penalties. Our results allow a better understanding of the sensitivity and fitness of isolates of C. musae from Brazil, and demonstrate the importance of periodic monitoring to determine the frequency of LS isolates in populations, aiming at more effective management of anthracnose in banana orchards in Brazil.     

Penicillium digitatum Suppresses Production of Hydrogen Peroxide in Host Tissue During Infection of Citrus Fruit

ABSTRACT During the infection of citrus fruit by Penicillium digitatum there is little evidence of a host defense response. This suggests that P. digitatum has the ability to suppress host defenses. The current study demonstrates that P. digitatum suppresses a defense-related hydrogen peroxide (H(2)O(2)) burst in host tissue. In contrast, the nonhost pathogen, Penicillium expansum, triggers production of a significant amount of H(2)O(2) in citrus fruit exocarp. Using laser scanning confocal microscopy, we demonstrated that P. digitatum suppressed an elevation in H(2)O(2) up to 42 h after inoculation. Nevertheless, H(2)O(2) levels around wounds inoculated with P. expansum increased by 63-fold above the control. P. digitatum continued to suppress H(2)O(2) production in citrus fruit exocarp up to 66 h postinoculation and H(2)O(2) levels were actually threefold below that of noninoculated controls. In contrast, the H(2)O(2) level was still about 11-fold above the control value in wound sites inoculated with P. expansum. Studies on the effect of organic acids (as pH modulators) on the response of citrus fruit to compatible and noncompatible pathogens indicated that pathogenicity was enhanced only when host-tissue acidification was accompanied by the suppression of H(2)O(2). Additionally, pathogenicity of both P. digitatum and P. expansum on citrus fruit was significantly enhanced by the H(2)O(2)-scavenging enzyme catalase. Based on our study and previous reports regarding the potential involvement of citric acid and catalase in green mold pathogenesis, we suggest that these compounds are strongly associated with the virulence of P. digitatum.     

Characterization of Fusarium spp. responsible for causing dry rot of potato in Great Britain

A 3-year survey was undertaken to establish the relative frequency of different Fusarium spp. present as inoculum on potato tubers collected from four regions of Great Britain. A total of 219 samples (comprising 10 950 tubers) were collected from the 2000, 2001 and 2002 crops and processed to recover dry rot-producing isolates. In total, 228 isolates of Fusarium spp. were recovered. Most (94·7%) of these isolates were attributed to one of four Fusarium species: F. coeruleum, F. avenaceum, F. culmorum and F. sambucinum (formerly F. sulphureum) . The incidence of the combined Fusarium spp. increased the further south the crops had been grown. Fusarium coeruleum was the most commonly isolated species in each survey year, comprising 37 to 52% of the total Fusarium species. Selected isolates of each species were evaluated for their ability to produce rots in potato tubers. Fusarium sambucinum was a more aggressive pathogen than the other Fusarium species in eight out of 10 cultivars. Fusarium avenaceum and F. culmorum were relatively weaker pathogens. However, these species were aggressive on some cultivars, notably Hermes. The selected isolates were also assessed for their sensitivity to the fungicides thiabendazole and imazalil. Using in vitro tests, 65% of F. sambucinum isolates were resistant to thiabendazole and 7% of F. avenaceum isolates were resistant to imazalil. Tubers treated with imazalil yielded a higher proportion of isolates of F. avenaceum than those that were untreated. Similarly, a higher proportion of F. sambucinum isolates were recovered from tubers treated with thiabendazole than from those that were not treated.     

Intraspecific Variation in Phytophthora citrophthora from Citrus Trees in Eastern Corsica

Isolates of Phytophthora pathogenic to citrus crops on Eastern Corsica and associated with gummosis were identified by PCR-RFLP of internal transcribed spacers (ITS) sequences and characterized by the random amplified microsatellites (RAMS) technique. A sample of 114 isolates collected from diseased trunks and fruits, and from soil, were overwhelmingly Phytophthora citrophthora. Further analysis indicated that the P. citrophthora population was not homogeneous in citrus groves. There were two groups, with a few (4%) atypical isolates in two marginal groups. The major groups have been re-examined in the light of mating behaviour, RFLPs of mitochondrial DNA and sequence comparisons of ITS regions of rDNA. They were found distinct with all these criteria and perhaps constitute distinct taxa. The results indicate that important modifications occurred in the population structure of P. citrophthora over time in Corsican groves. These changes may have impact on the recent outbreaks of gummosis.     

Sensitivity to Protectant Fungicides and Pathogenic Fitness of Clonal Lineages of Phytophthora infestans in the United States

ABSTRACT Since 1991, dramatic changes have occurred in the genetic composition of populations of Phytophthora infestans in the United States. Clonal lineages recently introduced into the United States (US-7 and US-8) are more common now than the previously dominant lineage (US-1). To help determine why these changes occurred, four clonal lineages of P. in-festans common during the early 1990s in the United States and Canada were evaluated for sensitivity to the protectant fungicides mancozeb and chlorothalonil using amended agar assays for isolates collected from 1990 to 1994. No isolate or lineage was resistant to either mancozeb or chlorothalonil. There were significant differences among isolates for degree of sensitivity to one fungicide individually, but there were no significant (P = 0.05) differences among the US-1, US-6, US-7, and US-8 clonal lineages for degree of sensitivity to both fungicides. Therefore, resistance to protectant fungicides cannot explain the rapid increase in frequency of the US-7 and US-8 clonal lineages. Three components of pathogenic fitness (latent period, lesion area, and sporulation after 96 h) were tested for the three clonal lineages that were detected most commonly during 1994 (US-1, US-7, and US-8). All but one of the isolates in this analysis were collected during 1994 and evaluated within 10 months of collection by inoculating detached leaflets of the susceptible potato cultivar Norchip. There were significant differences between the US-1 and US-8 clonal lineages for lesion area and sporulation, and between US-1 and US-7 for latent period. The US-6 clonal lineage was excluded from the pathogenic fitness experiments, because no isolates of this lineage were collected during 1994. Compared with US-7 and US-8, US-1 had the longest latent period and the smallest lesions with the least sporulation. Incorporation of the differences between US-1 and US-8 in computer simulation experiments revealed that significantly more protectant fungicide (e.g., 25%) would be required to suppress epidemics caused by the US-8 clonal lineage compared with US-1. These differences in pathogenic fitness components probably contribute to the general predominance of the "new" clonal lineages (especially US-8) relative to the "old" US-1 lineage.     

Observations on the antisporulant activity of imazalil (enilconazole)

Imazalil, incorporated in a solid nutrient medium, had no effect on the sporulation of Penicillium italicum at concentrations that did not strongly inhibit mycelial growth. However, when the fungus was grown submerged in liquid culture, sporulation of P. italicum appeared to be more affected than vegetative growth; at 33 nM, imazalil completely prevented the formation of penicilli without adverse effects on growth. Imazalil was able to prevent sporulation in the vapour phase as shown by scanning electron microscopy on P. italicum and Aspergillus niger; the vapours of the compound were found to affect different stages of the sporulation process, depending on the timing of the experiment. Thus, in order to show antisporulant activity, imazalil had to reach the target site by means other than migration within the fungus.     

Characterisation of energy-dependent efflux of imazalil and fenarimol in isolates of Penicillium italicum with a low,medium and high degree of resistance to DMI-fungicides

Differential accumulation of [¹⁴C]imazalil and [¹⁴C]fenarimol by germlings of wild-type and DMI-resistant isolates ofPenicillium italicum was studied at various pH values. At pH 7 and 8 the low-resistant isolate E_300–3 accumulated 22% and 35%, respectively, less imazalil than the wild-type isolate W₅. Imazalil accumulation at pH 5 and 6 was similar. Isolate E_300–3 also accumulated less fenarimol as compared with the wild-type isolate. This difference was much more obvious than for imazalil and was observed at all pH values tested. Differences in accumulation of both imazalil and fenarimol between low (E_300–3), medium (H₁₇) and high resistant (I₃₃) isolates were not observed. These results suggest that decreased accumulation of DMIs is responsible for a low level of resistance only and that additional mechanisms of resistance might operate in isolates with a medium and high degree of resistance. With all isolates fenarimol accumulation was energy-dependent. This was not obvious for imazalil.The wild-type and DMI-resistant isolates had a similar plasma membrane potential as determined with the probe [¹⁴C]tetraphenylphosphonium bromide ([¹⁴C]TPP⁺). Various test compounds, among which ATPase inhibitors, ionophoric antibiotics and calmodulin antagonists, affected the accumulation of [¹⁴C]TPP⁺, [¹⁴C]imazalil and [¹⁴C]fenarimol. No obvious correlation between the effects of the test compounds on accumulation levels of the fungicides and [¹⁴C]TPP⁺ could be observed. These results indicate that the plasma membrane potential does not mediate the efflux of DMI fungicides byP. italicum.     

Evaluation of food additives and low-toxicity compounds as alternative chemicals for the control of Penicillium digitatum and Penicillium italicum on citrus fruit

The effectiveness of low-toxicity chemicals as possible alternatives to synthetic fungicides for the control of post-harvest green and blue moulds of citrus was evaluated. A preliminary selection of chemicals, mostly common food additives, was made through in vivo primary screenings with oranges artificially inoculated with Penicillium digitatum or P italicum. Selected compounds and mixtures were tested as heated solutions in small-scale trials. Immersion of artificially inoculated oranges or lemons for 120 s in solutions at 40.6 degrees C and natural pH of potassium sorbate (0.2 M), sodium benzoate (0.2 M) or mixtures (0.1 + 0.1 M) of potassium sorbate with sodium benzoate, sodium propionate or sodium acetate were the most effective organic acid salts tested and reduced green mould by 70-80% after 7 days of storage at 20 degrees C. The mixtures did not significantly enhance the effectiveness of potassium sorbate or sodium benzoate alone. These solutions were as effective as sodium carbonate or calcium polysulphide treatments and, in general, they were more effective on lemons than on oranges. Satisfactory control of green and blue moulds was obtained by dipping oranges for 150 s in solutions of sodium molybdate (24.2 mM) or ammonium molybdate (1.0 mM) at 48 or 53 degrees C, but not at 20 degrees C. At 53 degrees C, however, the effectiveness of hot water was not enhanced by either molybdate. Molybdenum salts at higher concentrations were phytotoxic and stained the fruit. At non-phytotoxic concentrations, the effectiveness of these solutions was more influenced by temperature than by concentration. In general, the inhibitory effects of all compounds tested were not fungicidal but fungistatic and not very persistent. In conclusion, potassium sorbate, sodium benzoate and ammonium molybdate, among the wide range of chemicals tested, were superior for the control of post-harvest Penicillium decay of citrus fruit.     

新型含氮化合物对柑桔绿霉菌的离体抑菌活性及其构效关系

为寻找对柑桔绿霉菌具有抑制作用的活性化合物,采用生长速率法并结合光谱法评价两种商品化三唑类杀真菌剂和四种新型含氮化合物对柑桔绿霉菌的抑菌活性及与柑桔绿霉菌CYP51的结合能力。结果表明:7-甲氧基-2-氢-苯并[b][1,4]噻嗪-3-胺对柑桔绿霉菌表现出强抑制作用,EC50值达1.18mg/L,与商品化三唑类杀真菌剂烯唑醇的EC50值(0.09mg/L)接近;而其余三种新型含氮化合物显示出中等程度的抑制作用,EC50值分别为7.88、10.09和38.56mg/L。不同化合物与异源表达的重组柑桔绿霉菌CYP51的结合能力不同,对柑桔绿霉菌生长抑制的EC50越大,结合常数越大,即化合物与靶标酶CYP51的结合能力与抑菌活性呈正相关。