草莓枯萎病菌对多菌灵的抗性及其抗性菌株生物学特性

为评价草莓枯萎病菌对多菌灵的抗性风险,从山东有代表性的草莓种植区,采集、分离了4个草莓枯萎病菌菌株,分别在含多菌灵的PDA平板培养基上进行继代培养,诱导获得抗性菌株。采用菌落生长速率法测定抗性菌株ZY-D的抗性稳定性及其对其它杀菌剂的交互抗性,比较了抗性菌株ZY-D与敏感菌株ZY的生物学特性差异。结果显示:选育至45代,抗性菌株ZY-D对多菌灵的抗性达53.91倍,抗性能够在无药条件下稳定遗传,4个抗性菌株与敏感菌株ZY具有同样的致病力;抗多菌灵菌株ZY-D对甲基硫菌灵等7种药剂表现出了不同程度的交互抗性;抗性菌株ZY-D与敏感菌株ZY的适宜生长温度均为25℃,适宜pH均为9;在不同的碳、氮源条件下,ZY-D与ZY的菌落直径和产孢量存在差异。     

葡萄白腐病菌对抑霉唑的敏感基线及其与不同杀菌剂的交互抗性

为明确山东省胶东地区葡萄白腐病菌Coniella diplodiella对抑霉唑的敏感性及抑霉唑与常规杀菌剂之间的交互抗性,采用菌丝生长速率法测定葡萄白腐病菌对抑霉唑等杀菌剂的敏感性,并通过分析抑霉唑与戊唑醇、吡唑醚菌酯、福美双、多菌灵、代森锰锌毒力的相关性,判断抑霉唑与各药剂之间是否存在交互抗性。结果表明,供试69株葡萄白腐病菌菌株对抑霉唑的EC₅₀在0.13~55.53 μg/mL之间,最高值与最低值相差427.15倍;其频数分布图呈多峰曲线,第一主峰内EC₅₀平均值为6.34 μg/mL,可作为胶东地区葡萄白腐病菌对抑霉唑的敏感基线。与敏感基线相比,田间已出现抑霉唑低抗菌株,占检测总株数的8.70%,未检测到中、高抗菌株。选择3个抗性菌株连续继代培养10代后,其对抑霉唑的敏感性明显提高,说明其抗药性不能稳定遗传。抑霉唑EC₅₀对数值与戊唑醇、吡唑醚菌酯、福美双、多菌灵、代森锰锌的EC₅₀对数值之间的相关系数分别为0.799、-0.143、-0.089、-0.268和0.159,说明抑霉唑与戊唑醇存在一定的交互抗性,但与其他4种药剂之间不存在交互抗性。表明抑霉唑可用于胶东地区田间葡萄白腐病的有效防控。     

掘氏疫霉抗土菌灵突变体的诱导及其特性研究

掘氏疫霉Phytophthora drechsleri是引起黄瓜疫病的主要病原菌。采用紫外线诱导获得了20株掘氏疫霉抗土菌灵的突变体,并对其生物学特性进行了研究。结果表明,掘氏疫霉对土菌灵 的抗性突变频率高于对甲霜灵的抗性突变频率,但其抗性水平低于抗甲霜灵突变体,在1.3~4.3倍 之间;掘氏疫霉对土菌灵的抗性在继代培养和常温保存过程中稳定,突变体的生长速率与亲本敏感 菌株相比发生了不同程度的变化;此外,掘氏疫霉抗土菌灵突变体对甲霜灵和烯酰吗啉无交互抗性。     

葡萄霜霉菌对仿生杀菌剂缬霉威的敏感基线及其抗性突变体生物学性状的研究

 本文对葡萄霜霉菌对缬霉威的抗性风险评估进行了研究。采集尚未使用过缬霉威的105个葡萄霜霉菌株,建立其对缬霉威的敏感基线。葡萄霜霉菌对缬霉威的有效抑制中浓度EC₅₀为0.04～0.60 μg·mL^-1,其敏感性频率符合正态分布,表明这105株葡萄霜霉菌对缬霉威均表现敏感。取其中10株敏感菌的孢子囊经紫外线(UV)诱导,获得4个缬霉威抗性突变体,突变频率为6.8×10^-7。将这10株葡萄霜霉菌孢子囊在叶片上进行缬霉威药剂驯化处理获得7个抗性突变体。11个抗性突变体的EC₅₀值为4.37～14.11 μg·mL^-1,抗性水平17.4～71.6。在未用药处理的健康葡萄叶片上继代培养10代后,这11个抗性突变体抗性水平保持在17.1～71.0。其中药剂驯化获得的7个抗性突变体和1个紫外诱导获得的抗性突变体的抗性水平均表现稳定遗传。但是,其余3个紫外诱导获得的抗性突变体抗性水平明显下降。与各亲本菌株进行比较,11个抗性突变体的潜育期、侵染率、病斑扩展速度和产孢能力都有显著不同。其中2个药剂驯化获得的抗性突变体和3个紫外诱导获得的抗性突变体表现潜育期变长,2个药剂驯化抗性突变体和1个紫外诱导抗性突变体表现侵染率下降。表明在一些情况下,葡萄霜霉菌抗性突变体的潜伏期和侵染率会发生改变。药剂驯化获得的抗性突变体产孢能力存在显著差异,但与抗性突变与否无关。缬霉威与嘧菌酯、甲霜灵、烯酰吗啉和霜脲氰之间无交互抗药性。推测:葡萄霜霉菌对缬霉威为中到高等抗性风险,今后应定期对葡萄霜霉菌对缬霉威的抗性发生动态进行监测。     

抗啶酰菌胺蔬菜灰霉病菌突变体的诱导及其生物学性状

为评价蔬菜灰霉病菌对啶酰菌胺的抗性风险,采用紫外线照射和药剂驯化相结合的诱导方法,对蔬菜灰霉病菌D9、L17、J9亲本敏感菌株进行了室内啶酰菌胺抗性诱导,并采用菌落直径法比较了抗、感菌株在生物学性状方面的差异。结果显示,共获得不同抗性水平的突变体23株,其中突变体D9-4的抗性倍数为253.76倍,达高抗水平。突变体菌丝生长速率较敏感菌株有所下降,抗、感菌株的适宜生长温度均为25 ℃,敏感菌株最适pH为5,突变体最适pH为7,突变体适应酸碱度和温度变化的能力较敏感菌株差;低抗突变体产孢量和孢子萌发率与敏感菌株无显著差异,但高抗突变体产孢量和孢子萌发率较敏感菌株显著降低;在无药条件下,敏感菌株致病力强于抗性突变体,而在药剂胁迫下,突变体表现出一定的耐药性,致病力强于敏感菌株;6株突变体无药继代培养15代后,突变体抗性稳定遗传。此外,蔬菜灰霉病菌对啶酰菌胺与其它5种杀菌剂之间没有交互抗性。研究表明,蔬菜灰霉病菌抗啶酰菌胺突变体适合度较低,但在药剂选择压力下容易形成啶酰菌胺抗性群体,在生产中需引起注意。     

禾谷镰孢菌对戊唑醇抗药性的诱导及抗性菌株特性研究

通过紫外线诱导获得了8株对戊唑醇具有不同抗性水平的禾谷镰孢菌Fusarium graminearum抗药突变体,其抗性倍数均≥30倍,最高达到186.03倍。将抗药突变体在无药培养基上继代培养9代后,其抗性倍数逐渐下降,抗药性可能不能稳定遗传。与亲本菌株相比,抗药突变体在菌落生长速率、菌丝干重、对温度和pH值的敏感性方面均有所下降,推测禾谷镰孢菌对戊唑醇可能具有中等或高抗药性风险。室内交互抗性测定结果表明,戊唑醇对苯醚甲环唑、多菌灵、异菌脲、百菌清及福美双均无交互抗性。     

芒果炭疽病菌对多菌灵的抗药性

对来自广东和海南等不同果园的芒果炭疽病菌进行了对多菌灵的抗性测定.结果表明,敏感菌株的最小抑制浓度(MIC)为0.110μg/mL,而抗性菌株在多菌灵500μg/mL下仍生长良好.抗性菌株经继代培养10代后抗性几乎不变,说明其抗性稳定.对抗、感菌株的生物学特性进行测定,然后以产孢量和致病力分别用MIC做简单相关性分析,证明病菌的生物学特性、产孢量、致病力与抗药性无关,因此可以认为病菌对多菌灵的抗药性突变并不影响其正常的生理功能.抗性菌株对甲基硫菌灵、苯菌灵、噻菌灵表现正交互抗性,而对乙霉威和咪鲜胺敏感.病菌在含药培养基上测定的敏感性与在经多菌灵处理过的离体果实上的敏感性有较好的对应关系,可用于大田抗药性的初步检测.     

大豆胶孢炭疽菌对苯醚甲环唑的抗性机制及其抗性突变体的适合度

为明确大豆胶孢炭疽菌Colletotrichum gloeosporioides对苯醚甲环唑的抗性风险及其抗性机制,采用药剂驯化法诱导获得其抗性突变体,并测定抗性突变体的适合度和交互抗性,同时分析抗性突变体和敏感菌株cyp51A和cyp51B基因的cDNA序列、启动区序列及相对表达量。结果表明:从大豆胶孢炭疽菌2株敏感菌株中筛选获得7株低抗苯醚甲环唑的突变体,突变频率为1.75×10^-4,其抗药性可以稳定遗传。抗性突变体与亲本敏感菌株在对温度的敏感性、菌丝生长速率、产孢量和致病力方面均存在一定差异。苯醚甲环唑与丙环唑之间存在中等交互抗性(相关系数为0.80,P<0.05),苯醚甲环唑与咪鲜胺锰盐、多菌灵、氟啶胺和吡唑醚菌酯之间无交互抗性。抗性突变体cyp51A和cyp51B基因的cDNA序列未发生核苷酸突变,cyp51A和cyp51B基因的启动区无插入片段。经苯醚甲环唑处理后,4株抗性突变体lq27-7-1、lq27-7-2、lq30-2-1和lq30-2-2的cyp51A基因相对表达量被诱导上调倍数显著高于亲本敏感菌株;3株抗性突变体lq27-7-2、lq...     

灰霉病菌对三种杀菌剂的抗性表现型分布及稳定性测定

采用最低抑制浓度法(MIC)和菌落直径法,对采自山西晋中、晋南、晋东南和晋北4个地区的188个灰霉病菌株对3种杀菌剂的抗性表现型和稳定性进行了测定,旨在了解灰霉病菌的抗药性状况和预测其抗性发展趋势。结果表明:对多菌灵的抗性表现型可分为敏感(S)、低抗或中抗(RM)和高抗(R),对腐霉利和乙霉威可分为敏感(S)和抗性(R)。以对多菌灵、腐霉利和乙霉威的抗性为序,检测出8种不同类型的抗性表现型,即RRR、RRS、RSR、RSS、RMRS、RMSR、RMSS 和SSR。各表现型的分布频率随各地区用药历史和水平的不同而变化,并与抗性监测结果相一致。对55个不同抗性表现型的单孢菌株的稳定性测定结果表明:继代无药培养10代后,以RRR和RSS型表现最稳定,而其余类型菌株均不同程度发生了变异,尤其是RMSS和RMRS型菌株100%发生了变异,抗性表现型不稳定的菌株占52.7%。对多菌灵的抗性变化趋势是由敏感向低抗、再向高抗发展;对腐霉利的抗性变化主要是由抗性转变为敏感;而对乙霉威的抗性则相对比较稳定。     

辽宁省蔬菜灰霉病菌对嘧霉胺的抗药性

2006年从辽宁省不同地区采集蔬菜灰霉病果或病叶,经分离共获得灰霉病菌株86株。采用菌丝生长速率法测定了其对嘧霉胺的敏感性。试验结果表明,灰霉病菌对嘧霉胺产生中等水平抗药性,抗性频率为17.41%。经紫外、药剂联合诱导获得了高抗菌株,抗性倍数最高达62.78倍。嘧霉胺与多菌灵和腐霉利间不存在交互抗药性,苯胺基嘧啶类杀菌剂之间存在交互抗性。野生抗性菌株具有较好的遗传稳定性,连续转接9次后抗药性无明显下降。不同菌株的菌丝生长速度、鲜重和产孢量存在明显差异,但该差异与灰霉病菌对嘧霉胺的敏感性无相关性。     

不同类型Monilinia fructicola菌株的温度适应性及其对苯并咪唑类杀菌剂和乙霉威的交互抗性

褐腐病菌Monilinia fructicola是引起多种果树褐腐病的重要病原菌,前期研究发现该病原菌对甲基硫菌灵的抗性与Tub2蛋白的多个氨基酸变异有关.为明确不同类型菌株的温度适应性及乙霉威是否对所有抗性类型菌株均具有抑菌活性,本研究测定了敏感型菌株S及3种抗性类型包括R(E198A)、R(E198Q)及R(F20...     

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

 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。     

Thiophanate-methyl and carbendazim resistance in Fusicoccum amygdali,the causal agent of constriction canker of peach and almond

In light of growing environmental concerns, surveys of fungicide resistance are needed to ensure efficient control of fungi and avoid unnecessary treatments. Investigations of fungicide resistance in Fusicoccum amygdali are scarce despite the economic impacts of this pathogen in peach and almond orchards. Thiophanate-methyl has been registered for more than 20 years to control F. amygdali but no resistance has been reported to date. This propesticide is metabolized by fungi into carbendazim, a β-tubulin inhibitor. Sensitivity to carbendazim of nine populations of F. amygdali from French orchards was assessed using germination bioassays. Also, resistance levels of 63 strains isolated from four populations were evaluated using mycelial growth assays. The underlying mechanism of resistance was investigated by sequencing the β-tubulin gene, the molecular target of thiophanate-methyl, in a set of isolates with different levels of sensitivity to carbendazim. Cross-resistance to thiophanate-methyl and to another β-tubulin inhibitor, diethofencarb, was also assessed in carbendazim-sensitive and -resistant strains. Isolates highly resistant to carbendazim were found in one of the nine orchards studied. Sequencing showed that resistant phenotypes carry a mutation in the β-tubulin gene leading to E198K substitution. Positive cross-resistance to thiophanate-methyl was confirmed and no negative cross-resistance to diethofencarb was identified in the phenotyped isolates, which were all resistant to this active substance. To our knowledge, this is the first report of resistance to thiophanate-methyl in F. amygdali. The high level of resistance of isolates sampled in one population is of concern, although the limited geographical scope of resistance suggests its recent emergence.     

Identification of a novel point mutation in the <Emphasis Type="Italic">β</Emphasis>-tubulin gene of <Emphasis Type="Italic">Botrytis cinerea</Emphasis> and detection of benzimidazole resistance by a diagnostic PCR-RFLP assay

The molecular basis of resistance to benzimidazole fungicides with laboratory and field mutant isolates of Botrytis cinerea was investigated. After chemical mutagenesis with N-methyl-N-nitrosogouanidine (NMNG) two different benzimidazole-resistant phenotypes were isolated on media containing carbendazim or a mixture of carbendazim and diethofencarb. The mutant isolates from the fungicide-mixture-containing medium were moderately resistant to carbendazim with wild-type tolerance to diethofencarb while mutant isolates from carbendazim-containing medium were highly resistant to carbendazim but sensitive to diethofencarb. The studied field isolates were highly resistant to benzimidazoles and sensitive to diethofencarb. Study of fitness characteristics of benzimidazole highly-resistant isolates showed that the resistance mutation(s) had no apparent effect on fitness-determining parameters. Contrary to this, the moderately benzimidazole-resistant strains, with no increased diethofencarb sensitivity, had a significant reduction in certain ecological fitness-determining characteristics. Analysis of the sequence of the β-tubulin gene revealed two amino acid replacements in the highly benzimidazole-resistant mutants compared to that of the wild-type parent strain. One was the glutamic acid (GAG) to alanine (GCG) change at position 198 (E198A), identified in both laboratory and field highly benzimidazole-resistant isolates, a mutation previously implicated in benzimidazole resistance. The second was a novel benzimidazole resistance mutation of glutamic acid (GAG) to glycine (GGG) substitution at the same position 198 (E198G), identified in a highly benzimidazole-resistant laboratory mutant strain. Molecular analysis of the moderately benzimidazole-resistant strains revealed no mutations at the β-tubulin gene. A novel diagnostic PCR-RFLP assay utilising a BsaI restriction site present in the benzimidazole-sensitive (E198) but absent in both resistant genotypes (E198G and E198A) was developed for the detection of both amino acid replacements at the β-tubulin gene.     

番茄叶霉病菌对多菌灵、乙霉威及代森锰锌抗性检测

报道了番茄叶霉病菌Fulvia fulva对多菌灵、乙霉威及代森锰锌的敏感性基线,以及抗性频率和抗性水平。离体条件下,多菌灵、乙霉威及代森锰锌对番茄叶霉病菌敏感菌株的平均EC50值分别为0.101、2.475、9.067 μg/mL;最低抑制浓度(MIC)值分别为0.5、5、50 μg/mL 。山西晋南地区番茄叶霉病菌对3种杀菌剂的抗性频率最高,分别达到97.4%、70.5%、98.7%;山西吕梁地区与太原地区相对较低,但该病菌对3种杀菌剂的抗性频率也都超过了30%。辽宁沈阳、山东寿光、河北保定番茄叶霉病菌对多菌灵的抗性频率均为100%;对乙霉威的抗性频率前两地为100%,保定为10%;对代森锰锌的抗性频率都超过90%。所有抗性菌株对多菌灵均属于高抗类型,抗性指数超过5000,测不出MIC值;对乙霉威有50%的高抗菌株,抗性指数在100以上;对代森锰锌各地均未发现高抗菌株,低抗和中抗菌株所占比例较大,其抗性指数集中在50左右。对多菌灵与乙霉威具有双重抗性的菌株占测试菌株总数的49.9%,并且首次在田间发现了对3种杀菌剂都具有抗性的番茄叶霉病菌多抗菌株。     

番茄叶霉病菌异菌脲抗药性突变体的诱导与生物学性状

测定了苯并咪唑类杀菌剂敏感-乙霉威抗性(BenS-DieR)、苯并咪唑类杀菌剂抗性-乙霉威敏感(BenR-DieS)和苯并咪唑类杀菌剂抗性-乙霉威抗性(BenR-DieR)3种类型的番茄叶霉病菌Cladosporium fulvum菌株对不同类型药剂的敏感性。结果表明,蕃茄叶霉病菌对供试药剂的敏感性与其对苯并咪唑类杀菌剂及乙霉威的敏感性无关。根据药剂对3类菌株EC50值的平均值, 16种杀菌剂抑制菌丝生长的活性依次为腐霉利＞乙烯菌核利＞异菌脲＞戊唑醇＞百菌清＞嘧霉胺＞醚菌酯＞代森锰锌＞8-羟基喹啉铜＞丙环唑＞苯醚甲环唑＞嘧菌酯＞灭锈胺＞烯酰吗啉＞烟酰胺＞三唑酮;抑制孢子萌发的活性依次为醚菌酯＞腐霉利＞百菌清＞乙烯菌核利＞灭锈胺＞8-羟基喹啉铜＞异菌脲＞代森锰锌＞嘧菌酯＞烟酰胺＞嘧霉胺＞戊唑醇＞丙环唑＞苯醚甲环唑＞三唑酮＞烯酰吗啉。通过紫外诱变共获得17株抗异菌脲突变体,突变频率为4.5×10-7。其中低抗、中抗和高抗菌株分别占 17.65%、70.59%和11.75%。这些突变体对腐霉利和乙烯菌核利表现交互抗性,对苯并咪唑类、脱甲基抑制剂(DMIs)、QoIs等药剂的敏感性与亲本菌株之间没有显著性差异,与亲本菌株在生长、产孢、致病能力等方面也无显著差异,但对渗透胁迫的敏感性要显著高于亲本。     

Molecular characterization of benzimidazole-resistant B. cinerea field isolates with reduced or enhanced sensitivity to zoxamide and diethofencarb

Sensitivity profiles of Botrytis cinerea field isolates to zoxamide and the molecular basis of the resistance mechanism involved in cross-resistance relationships between benzamides, benzimidazoles and N-phenylcarbamates were investigated. B. cinerea isolates collected from southern, central and northern Greece were characterized based on their sensitivity to zoxamide, the benzimidazole carbendazim and the N-phenylcarbamate diethofencarb. Isolates exhibiting baseline sensitivity to carbendazim and zoxamide but no sensitivity to diethofencarb were considered wild type (S phenotype) and accounted for 44% of the total strains sampled. Thirty-three percent of the isolates had increased sensitivity (HS phenotype) to zoxamide and diethofencarb and were highly resistant to carbendazim compared to S isolates. Eight percent of the sample was highly resistant (HR phenotype) to all anti-tubulin agents studied. The rest of the isolates were moderately resistant to zoxamide (MR phenotype) and equally sensitive to benzimidazoles and N-phenylcarbamates compared to isolates of the S phenotype. Fungitoxicity tests with botrycides belonging to other chemical classes revealed no cross-resistance relationships between zoxamide and the phenylpyrrole fludioxonil, the dicarboximide iprodione, the hydroxyanilide fenhexamid, the anilinopyrimidine cyprodinil, the carboxamide boscalid and the strobilurin-type fungicide pyraclostrobin. Study of fitness characteristics did not show any significant difference between zoxamide resistant and sensitive isolates with respect to the parameters tested. PCR-RFLP analysis of a part of the β-tubulin gene sequence detected mutations in position 198 for both HS and HR zoxamide-sensitivity phenotypes. DNA sequence analysis of the B. cinerea β-tubulin gene revealed two previously described benzimidazole-resistance-conferring mutations. The first one was the glutamic acid (GAG) to alanine (GCG) change at position 198 (E198A), which was identified in all HS isolates. The second mutation (E198K) was a GAG-to-AAG substitution resulting in the replacement of glutamic acid with lysine present in all B. cinerea isolates highly resistant to all three anti-tubulin classes of fungicides. A number of mutations in other positions of the β-tubulin gene were detected in the moderately zoxamide-resistance phenotype.     

Cross-resistance relationships between benzimidazole fungicides and diethofencarb in Botrytis cinerea and their genetical basis in Ustilago maydis

After nitrosoguanidine- or UV-mutagenesis, three different benzimidazole-resistant phenotypes were isolated on media containing benomyl or a mixture of carbendazim and diethofencarb from wild-type strains of Botrytis cinerea Pers. ex Fr. and Ustilago maydis (D.C.) Corda. Mutants of B. cinerea with moderate (MBr) or low (LBr) resistance to benzimidazoles and high resistance to diethofencarb (Dr) were isolated from the fungicide-mixture-containing medium in low frequency (7–1 × 10^?8). Only benzimidazole-resistant strains highly sensitive to diethofencarb (HBrDs) were identified on benomyl-containing medium at a frequency of 6.6 × 10^?6. Fitness-determining characteristics such as sporulation, germination and germ-tube elongation, were found to be reduced significantly in the mutants of B. cinerea that were resistant to both benzimidazoles and diethofencarb. However, pathogenicity of a MBrDr mutant strain on cucumber seedlings was equal to that of the wild type and a carbendazim + diethofencarb mixture was found to control grey mould caused by the wild type, but was not effective when the plant cotyledons were infected by the mutant strain. Three benzimidazole-resistant phenotypes (HBrDs, HBrDr, MBrDr) were isolated easily in U. maydis from a benomyl-containing medium. In contrast with B. cinerea, only one-tenth of the benzimidazole-resistant strains were sensitive to diethofencarb. Genetic analysis of benzimidazole resistance in U. maydis showed that the three benzimidazole-resistant phenotypes were due to three allelic mutations in a single gene and one of them was responsible for the negative cross-resistance between benzimidazoles and diethofencarb.     

西瓜蔓枯病菌啶酰菌胺抗性突变体的生物学特性研究及其Sdh B基因位点检测

为评价西瓜蔓枯病菌对啶酰菌胺的抗性风险,了解其抗性机理,室内通过药剂驯化方法获得2株啶酰菌胺的抗性突变体XF21-3和YC60-1,测定了抗性突变体的生物学特性,并通过对Sdh B基因片段的测序比对,分析了西瓜蔓枯病菌对啶酰菌胺的抗性机理。生物测定结果表明:啶酰菌胺对2株抗性突变体的EC50值分别为108和124 μg/mL,抗性倍数（RR）分别为1 007和1 347,均为高抗菌株;抗性突变体的菌丝生长速率和产孢量均大于亲本菌株,但其致病性与亲本菌株无显著差异,对外界环境渗透压的敏感性低于亲本菌株;此外,啶酰菌胺与萎锈灵、戊唑醇、乙霉威及醚菌酯之间均不存在交互抗性,但与噻呋酰胺之间存在交互抗性。Sdh B基因片段测序及比对结果表明,高抗性突变体中Sdh B亚基277位上的氨基酸所对应的碱基由CAC突变为TAC,即由组氨酸（His）突变为酪氨酸（Tyr）。研究表明,西瓜蔓枯病菌在药剂选择压力下容易形成啶酰菌胺的抗性群体,且抗性突变体的离体适合度高于亲本菌株,此外,啶酰菌胺与同类型杀菌剂噻呋酰胺之间存在交互抗性,因此认为西瓜蔓枯病菌对啶酰菌胺具有中等抗性风险;同时进一步验证了Sdh B亚基277位上的氨基酸突变（His→Tyr,CAC→TAC）是西瓜蔓枯病菌对啶酰菌胺产生抗性的原因。