安徽省栝蒌叶枯病菌对4种杀菌剂的敏感性

由致病性链格孢引起的叶枯病是栝蒌生产上出现的一种新病害,在安徽大别山栝蒌生产区发生严重。本研究采用菌丝生长速率法测试了12个代表性栝蒌叶枯病菌菌株对4种常用杀菌剂的敏感性。结果表明,栝蒌叶枯病菌对咪鲜胺敏感性较高,其EC50为0.013 0~0.219μg/mL;代森锰锌和百菌清对栝蒌叶枯病菌均有一定的抑制作用,但各菌株对代森锰锌和百菌清的敏感性差异较大,其EC50分别为0.997~95.64μg/mL和1.66~185.84μg/mL;多菌灵对栝蒌叶枯病菌的菌丝生长抑制作用较差。     

木霉几丁质酶对烟草赤星病菌的作用

以指形管培养法分别测定几丁质酶粗酶液和纯化的几丁质酶混合液(2种几丁质酶)对烟草赤星病菌孢子萌发的抑制作用。结果表明,较高浓度(25 2U)几丁质酶粗酶液在48h内强烈抑制孢子萌发和芽管伸长,或致芽管畸形和细胞壁破裂;几丁质酶混合液对赤星病菌的孢子萌发也表现出明显的抑制作用,但在相同或相近酶活性条件下,纯化的几丁质酶混合液(9 4U)和粗酶液(12 6U)对赤星病菌孢子萌发的抑制率(处理24h时)分别为46%和84 3%,前者明显低于后者。采用孢子液悬滴法接种烟苗(K 326)叶片测定木霉几丁质酶对赤星病菌致病性的影响。结果表明,几丁质酶粗酶液浓度越高,对孢子萌发抑制时间越长,抑制率越高;其浓度为4 9、9 8、19 5U/ml的抑制率7d时分别为36 8%、56 2%和57 6%。     

Genetic Analysis of Pathogenicity and Host-specific Toxin Production of Alternaria alternata Tomato Pathotype by Protoplast Fusion

Several pathotypes of Alternaria alternata are known to produce host-specific toxins (HSTs) as agents of pathogenicity or virulence. However, investigations into the genetic controls of HST biosynthesis and pathogenicity of Alternaria pathogens have been limited by the lack of a sexual stage in the life cycle of these pathogens. We report here the development of a protoplast fusion system and its use for genetic analysis of HST production and specific pathogenicity of the tomato pathotype of A. alternata that produces AAL-toxin as a HST. Drug-resistant transformants have been isolated by genetic transformation of nonpathogenic A. alternata (strain O-94) and A. alternata tomato pathotype (strain As-27) with vectors conferring resistance to hygromycin B and geneticin, respectively. Protoplasts of the respective transformants were fused by polyethylene glycol treatment or electrofusion. Fusion products were selected by culturing in the presence of both hygromycin B and geneticin, then confirmed by amplification using a polymerase chain reaction with specific primers to the transforming drug-resistance genes. Stable fusants were purified by successive subcultures on selective medium and single-spore isolation. The resultant stable fusants, probably inter-strain hybrids, had the same pathogenicity and toxin production as the wild-type strain As-27. These results suggest that protoplast fusion has potential applications for genetic analysis of A. alternata pathogens. Received 8 September 2000/ Accepted in revised form 27 October 2000     

Cultivar reactions and the genetic basis of resistance to alternaria stem canker (Alternaria alternata f.sp. lycopersici) in tomato

The reactions of several tomato cultivars and the genetic basis of resistance to an isolate of Alternaria alternata f. sp. lycopersici were examined. Among the 105 cultivars tested only two, Regal and Toper, were susceptible, while the remainder were highly resistant. The resistant cultivar ACE 55 VF (P_;) was crossed with the susceptible cultivar Earlypak No. 7 (P₁)- When F₁, F₂, F₃, BC₁, BC₁ selfed, F₂ X P₂ and BC₁P₂ x P₁ progenies were inoculated at the two-leaf stage with a suspension of spores of the pathogen, the ratios of resistant to susceptible plants indicated that resistance was conferred by a single dominant gene.     

Pathological evaluation of host-specific AAL-toxins and fumonisin mycotoxins produced by Alternaria and Fusarium species

Host-specific AAL-toxins and mycotoxin fumonisins are structurally related and were originally isolated from the tomato pathotype of Alternaria alternata and from Fusarium verticillioides, respectively. Previous reports on the production of fumonisin derivatives by the tomato pathotype suggested a possible involvement in the pathogenicity of the pathogen. Here, we have evaluated the role of fumonisin in A. alternata–tomato interactions. The results indicate that highly pathogenic isolates of A. alternata tomato pathotype produce AAL-toxin as the sole toxin, strongly implicating it as a pathogenicity factor. The related compound, fumonisin, is also toxigenic and has infection-inducing activity on susceptible tomato plants.     

Laboratory Evaluation of Citrus Cultivars Susceptibility and Influence of Fruit Size on Fortune Mandarin to Infection by Alternaria alternata pv. citri

Young leaves of 62 citrus cultivars were inoculated with conidia of three Spanish isolates of Alternaria alternata pv. citri, the causal agent of brown spot of citrus. Hybrids with Dancy mandarin, King mandarin or their derivates as a parent, grapefruit cultivars and the mandarin cultivars Guillermina, Emperor, Clemenpons and Esbal were highly susceptible to the pathogen. Satsuma cultivar Clausellina and orange cultivars, with the exception of Sanguinelli, were slightly susceptible. Lemon and lime cultivars were not susceptible, with the exception of Mexican lime (Citrus aurantifolia), which was slightly susceptible. Although this study shows a range of potential hosts for this pathogen, to date the only affected cultivars in Spain are Fortune and Nova mandarins, and Minneola tangelo. The susceptibility of Fortune fruits decreased as diameter increased, being susceptible through the whole season. This was confirmed with field observations in autumn where fruit infections have been detected when the diameter reaches 6–7 cm.     

2008年我国部分麦区小麦白粉病菌群体对温度的敏感性

 The sensitivity of 113 isolates of wheat powdery mildew (Blumeria graminis f. sp. tritici) sampled from 6 provinces or cities in 2008 to temperature was tested by detached leaf segment method with setting up 5 different temperatures indoor. The results showed the mean ET₅₀ (which represents the temperature that is required to obtain 50% of the maximum effect) of all isolates tested was 23.02℃. ET₅₀ values of 17.70% isolates were more than 24℃. The highest and the lowest ET₅₀ of isolates were 25.22℃ and 19.42℃, respectively. There were a certain differences for isolates sensitivity to temperature among different provinces or cites. It was also found that when temperature increased during 22-26℃, the latent period of isolates prolonged, and the latent period of different isolates was different at the same temperature, too. These results will provide a reference for the oversummering division of wheat powdery mildew, as well as the effect of climate to the disease.     

马铃薯早疫病菌对咯菌腈的敏感基线及其对不同药剂的交互抗性

采用菌丝生长速率法测定了河北省马铃薯主产区的122株早疫病菌Alternaria alternata对咯菌腈的敏感性,并测定了紫外诱导的15个抗咯菌腈突变菌株及其3个敏感亲本菌株对咯菌腈、异菌脲、腐霉利、苯醚甲环唑、吡唑醚菌酯的敏感性。田间马铃薯早疫病菌群体对咯菌腈保持高度敏感,122株早疫病菌对咯菌腈的EC₅₀值在0.0025~0.0857 μg/mL之间,平均值为0.0404±0.0171 μg/mL,相差34.87倍,呈近似正态分布,可作为早疫病菌对咯菌腈的敏感基线。此外,咯菌腈与吡唑醚菌酯和苯醚甲环唑之间无交互抗性关系,而与异菌脲和腐霉利之间存在正交互抗性关系。在田间药效试验中,50%咯菌腈WP施药量为105、115 g/hm²时,对马铃薯早疫病防效达80%以上,显著高于常规药剂80%代森锰锌WP 1 350 g/hm²和25%丙环唑EC 37.5 g/hm²的防效。表明咯菌腈可作为吡唑醚菌酯和苯醚甲环唑的替代药剂用于马铃薯早疫病的防治。     

苹果斑点落叶病菌对戊唑醇敏感基线建立及抗性突变体适合度

本研究测定了苹果斑点落叶病菌对戊唑醇的敏感性,并建立了敏感基线;在此基础上,室内筛选获得了9株抗戊唑醇突变体,对其适合度进行了测定,为指导戊唑醇防治苹果斑点落叶病提供理论依据。在山西省5个地市未使用过戊唑醇及同类药剂的果园中采集分离得到64株苹果斑点落叶病菌,敏感性测定结果表明,其EC50值在0.768 7~2.673 8μg·mL~(-1)之间,平均值为1.622 4±0.558 2μg·mL~(-1),呈连续性单峰曲线,可作为苹果斑点落叶病菌对戊唑醇的相对敏感基线。通过紫外线(UV)诱导获得低抗突变体6株,药剂驯化获得中抗突变体3株。2株中抗突变体抗药性可稳定遗传;低抗突变体在无药剂胁迫时,药剂敏感性上升。抗性突变体适合度测定结果显示,突变体菌丝生长速率、产孢量、孢子萌发率及分生孢子竞争力均低于敏感菌株。突变体在无药情况下致病力比敏感菌株弱。     

2011年我国主要麦区小麦白粉病菌群体对三唑酮和苯锈啶的敏感性

 小麦白粉病(Wheat Powdery Mildew)是我国小麦生产上常发性病害之一^[1]。小麦白粉病的防治主要采用抗病品种和化学药剂,辅之以栽培措施的综合防治技术。由于目前生产上抗病品种相对缺乏,药剂防治成为我国小麦白粉病防治的主要措施之一^[2]。自20世纪80年代以来三唑类杀菌剂一直是我国防治小麦白粉病的主要药剂,由于长期、大范围、单一的使用导致小麦白粉病菌对三唑类杀菌剂的抗药性大大提高。监测结果表明,2009年我国小麦白粉病菌群体对三唑酮的平均抗性水平已经达到56.58倍,抗性频率达到99.09%,其中高抗菌株占49.09%^[3]。目前小麦白粉病菌对三唑酮的抗性形势十分严峻,寻找三唑类杀菌剂的替代药剂成为控制该病害的迫切需求。     

2009年我国部分麦区小麦白粉菌群体对三唑酮和嘧菌酯的敏感性测定

自1976年以来,三唑酮一直就是我国防治小麦白粉病的主要药剂.1991年首次在山东省发现抗性菌株,之后其他地区也相继有抗药性菌株的报道.本实验室从1995年就开始监测小麦白粉菌对三唑酮的抗药性,研究结果表明,平均抗性水平和抗性菌株的频率均总体呈上升趋势[1-3].     

Sensitivity of Red Delicious Apple Fruit at Various Phenologic Stages to Infection by Alternaria alternata and Moldy-core Control

The fungus Alternaria alternata, is considered to be the predominant fungus involved in moldy-core of Red Delicious strains of apple. In this paper, we report on the sensitivity of various phenologic stages to infection by A. alternata, and on the efficacy of various fungicides in controlling moldy-core disease in apple orchards. Artificial inoculations conducted in the orchard during 1999 and 2000 seasons revealed that the beginning of bloom (10–30%) and full bloom were the most susceptible developmental stages for infection. Natural infection with A. alternata in fruits was relatively high, reaching 44% and 46% of the fruits on control non-treated trees in 1999 and 2000. Four foliar applications of polyoxin B, difenoconazole and azoxystrobin, starting from the beginning of bloom until fruit set, reduced the number of infected fruits by 54–70%, 61–70% and 50–65%, respectively, compared with non-treated trees. Four or eight foliar applications of each fungicide provided similar levels of control. There were no significant differences between two, four or six foliar applications of difenoconazole, neither between two or four applications of polyoxin B. Adding CaCl₂, as a tank mixture with difenoconazole at full rate, did not improve efficacy. Alternaria was recovered from the inner part of the core region of 71–88% of the fruits of the non-treated control, but was recovered less frequently from the outside part of the core region. Fruits of difenoconazole and polyoxin B treated trees were less colonized with A. alternata at both the inner and outside parts of the core region, as compared with controls. Results indicate that a control programme based on spray applications of difenoconazole or polyoxin B, during bloom period, can effectively reduce Alternaria on Red Delicious.     

Effects of fusaric acid on cells from tomato cultivars resistant or susceptible toFusarium oxysporum f. sp.Lycopersici

Cell suspension cultures were set up from two tomato cultivars, one resistant, (Rio grande) and one susceptible (63.5) toFusarium oxysporum f. sp.lycopersici. Growth rates of the two cell cultures were comparable. Toxicity of fusaric acid, expressed as the fresh weight loss, was analyzed: It was significant in both cases after 10 h, but toxicity was twice as high for 63.5 suspension cells. In the same way, electrolyte leakage caused by fusaric acid was three times more important for 63.5 suspension cells. Moreover, fusaric acid treatment resulted in an acidification of the extracellular medium for 63.5 suspension cells (0.4 pH unit), whereas an alkalization was observed for Rio grande suspension cells (0.2 pH unit). Preliminary experiments suggest that fusaric acid was partially metabolized by Rio grande suspension cells, however, no detoxified forms of fusaric acid were detected either in cells or in culture filtrates. For these two tomato cultivars, the differences in sensitivity to fusaric acid of cultivated cells correspond to the differences in plant susceptibility toFusarium oxysporum f. sp.lycopersici.Abbreviations BAP 6-benzylaminopurine - conductivity - 2,4-D 2,4-dichlorophenoxyacetic acid - EtOAc ethyl acetate - FA fusaric acid - resistivity     

抗菌肽和几丁质酶基因提高烟草对黑胫病菌和赤星病菌的抗性研究

 通过农杆菌介导法将加信号肽修饰的人工合成杂合抗菌肽CEMA基因(SPCEMA),苜蓿防御素基因(AFP),苦瓜几丁质酶基因(CHI)以及SPCEMA-CHI、AFP-CHI、AFP-SPCEMA双价基因导入本明烟(Nicotiana benthamiana),并对转基因烟草T₀和T₁代进行了抗病性检测,比较了不同转基因植株的抗病效果。研究结果表明,转基因烟草对黑胫病菌(Phytophthora parasitica var.nicotianae)、赤星病菌(Alternaria alternata)的抗性均强于非转基因烟草,病情指数差异达极显著水平,其中转AFP-CHI双价基因烟草具有较强的抗性,与单价转基因烟草的抗性差异达显著水平。但各单价转基因以及双价转基因烟草之间对上述病菌并未表现出显著的抗病性差异。结果表明植物源的抗菌肽基因与几丁质酶基因在抗植物真菌病害中具有协同增效作用。     

小麦白粉病菌对氟唑菌酰羟胺的敏感基线建立

氟唑菌酰羟胺是一种新型琥珀酸脱氢酶抑制剂(succinate dehydrogenase inhibitor, SDHI)类杀菌剂,2019年在我国登记在小麦上防治赤霉病,为明确其对小麦白粉病的潜在防治效果,以及为监测小麦白粉病菌群体对其是否产生抗药性,本文采用离体叶段法测定了2000年前和2019年采自我国河南、山东等9省市的110株小麦白粉病菌菌株对氟唑菌酰羟胺的敏感性。结果表明,采自2019年的88株菌株,其EC50范围为0.010 2~0.766 8 μg/mL,平均EC50为(0.224 3±0.179 6)μg/mL;采自2000年前的22株菌株,其EC50范围为0.052 1~0.882 4 μg/mL,平均EC50为(0.356 3±0.279 6)μg/mL;两组菌株群体间的敏感性无显著差异。氟唑菌酰羟胺对110株菌株的EC50范围为0.010 2~0.882 4 μg/mL,平均EC50为(0.250 7±0.210 3)μg/mL,敏感性频率分布呈单峰曲线,可作为小麦白粉病菌对氟唑菌酰羟胺的敏感基线。本研究结果可为氟唑菌酰羟胺防治小麦白粉病以及未来监测该病原菌对药剂的抗性提供参考依据。     

小麦白粉病菌对甲氧基丙烯酸酯类杀菌剂敏感性及其交互抗性

 20世纪70年代后期以来,小麦白粉病在我国小麦产区上升为主要病害,严重制约小麦生产。沿海北部及淮北地区,小麦白粉病常年发生4级左右。目前麦类白粉病的防治药剂主要有三唑类、嘧啶类、苯并咪唑类、甲氧基丙烯酸酯类及硫代氨基甲酸盐类等。但小麦白粉病菌变异快,繁殖迅速,以及药剂长期单一使用,造成小麦白粉病菌易产生抗药性。1995年我国小麦白粉菌对三唑酮的平均抗性水平在16.8倍以上。因而,急需寻找和开发替代三唑酮防治小麦白粉病的新型药剂。甲氧基丙烯酸酯类杀菌剂继三唑类杀菌剂后出现, 是一类内吸保护型杀菌剂,主要作用于真菌的线粒体呼吸链中细胞色素bc1复合物,阻止电子传递,抑制真菌生长。此类药剂于1996年投入德国市场,尚未在我国小麦白粉病防治上大量使用。     

Molecular characterisation of vegetative compatibility groups in Fusarium oxysporum f. sp. radicis-lycopersici and f. sp. lycopersici by random amplification of polymorphic DNA and microsatellite-primed PCR

Random amplification of polymorphic DNA (RAPD-PCR) analysis was conducted on 48 isolates of Fusarium oxysporum f. sp. radicis-lycopersici (F.o.r.l.) from different geographic regions, representing all known vegetative compatibility groups (VCGs) except VCG 0097 and VCG 0099 and on eight isolates of F.oxysporum f. sp. lycopersici (F.o.l.), representing VCGs 0030, 0031, 0032 and 0033. Upon UPGMA (unweighted pair-group method with arithmetic averages) analysis of 86 RAPD-PCR markers generated by 16 informative primers and 44 markers obtained with eight microsatellite primers, a close relatedness was evident for F.o.r.l. isolates in VCGs 0090, 0092, 0096, and, to a lesser extent, for those in VCG 0093. Representatives of VCG 0091 formed a distinct group, while F.o.r.l. isolates in VCGs 0094 and 0098 were not distinguishable by the tested markers, most of which were also shared by F.o.l. isolates belonging to VCGs 0031 and 0033. F.o.l. isolates in VCGs 0030 and 0032 shared most of the molecular markers. The correlation between RAPD-PCR and microsatellite genetic distance was highly significant (R² = 0.77; P by Mantel test < 0.001). The molecular variability observed in both formae speciales is discussed in relation to the development of F.o.r.l.- and F.o.l.-specific diagnostic tools.     

2012年我国部分麦区小麦白粉菌群体对温度敏感性研究

采用小麦离体叶段法,设置18、22、23、24、25和26℃共6个温度处理,对2012年采集的小麦白粉菌样分离得到的139个单孢堆菌株的温度敏感性进行了测定,这些菌样分别采自于四川、北京、甘肃、河南、浙江、陕西、青海、山东、新疆和云南10省(市、区)。结果表明:供试的139个菌株平均ET50为23.14℃,其中ET50最高为24.46℃,最低为21.34℃;58.76%的供试菌株ET50值在23℃和24℃之间,仅有2.03%的供试菌株的ET50≥24℃。对供试菌株温度敏感性频率分布的正态检验结果发现,自然环境中小麦白粉病菌群体已受到温度的选择压力。此研究结果可为了解和预测全球气候变暖对小麦白粉病长期发生趋势的影响提供依据。     

Effect of application rate on the sensitivity of Erysiphe graminis f.sp. tritici to fenpropimorph

Two sprays of fenpropimorph per season were applied to a winter wheat field trial, at a range of rates, which included the full commercial rate, in order to test the effect of fenpropimorph sprays on the sensitivity of Erysiphe graminis f.sp. tritici. While a reduction in the sensitivity of the mildew isolates was detected after fungicide application, this was not dependent on the rate of fungicide applied. Reduced rates were not found to induce a larger shift towards insensitivity than the full commercial rate. Powdery mildew isolates were collected from 1993 to 1996 and their sensitivity to fenpropimorph determined in order to monitor sensitivity changes in the population. While a decline in sensitivity was noted from season to season, there was no correlation between a lower sensitivity and the rate of fenpropimorph previously used. Isolates collected in Scotland were found to be significantly less sensitive than those sampled in the south of England. ©1997 SCI     

2010-2011年小麦条锈菌群体的温度敏感性与毒性及遗传多样性的关系

为了明确小麦条锈菌毒性、遗传多样性以及温度敏感性三者之间的关系,本研究利用21个已知抗条锈病基因近等基因品系对2010-2011年生长季采自6个省市78株已知温度敏感性(ET50)的小麦条锈菌群体进行毒性鉴定,并利用AFLP技术对其进行遗传多样性分析。苗期毒性鉴定结果表明,不同省市小麦条锈菌群体的毒性基因多样性存在一定差异,甘肃菌株群体毒性多样性指数H值最高,为0.269 3,云南菌株群体最低,为0.150 4。遗传多样性结果显示,6省市小麦条锈菌群体遗传多样性指数H值范围在0.125 5~0.165 3之间,遗传一致度GI为0.964 7~0.987 2,遗传距离GD为0.012 9~0.036 0。三者的相关性分析表明,条锈菌群体毒性多样性与平均ET50显著负相关,与ET50变异系数正相关,而与遗传多样性没有显著的相关关系。