小麦白粉病纯化菌种保存方法

利用经初选确定的5种具有较好保鲜能力的配方,采用离体叶段滤纸保存法、离体叶段琼脂保存法和试管苗保存法对小麦白粉病菌纯化菌系保存效果进行了研究.结果表明,对小麦幼苗第一叶叶段保鲜效果最好的配方是沈保6号,当使用40～60μg/mL最适浓度时,第25天叶段绿色仍可达到90%以上.保存菌种的最适环境条件研究结果表明,在4℃冰箱中,以离体叶片沈保6号琼脂保存和离体叶沈保6号浸润滤纸保存效果最佳,在第40天叶片绿色仍分别达到78.0%和68.0%,孢子萌发率可达26.7%和26.8%.     

Antifungal substances produced by fungal strain Kyu-W63 from wheat leaf and its taxonomic position

Fungal strain Kyu-W63 from a wheat leaf suppressed the development of wheat powdery mildew caused by Blumeria graminis f. sp. tritici. Nuclear magnetic resonance analysis revealed that Kyu-W63 produced two volatile substances: 5-pentyl-2-furaldehyde and 5-(4-pentenyl)-2-furaldehyde. Although the two are known to be nematicidal substances, the antifungal activity of 5-(4-pentenyl)-2-furaldehyde was first confirmed in the present study. Culture experiments revealed that synthesized 5-pentyl-2-furaldehyde had antifungal activity against three other pathogens – Fusarium oxysporum f. sp. lycopersici, Colletotrichum fragariae, Botrytis cinerea – with a minimum inhibitory concentration of 2–4µg/ml. The two fractionated substances were also inhibitory against C. fragariae. Because the absence of spores in strain Kyu-W63 made its identification difficult, the sequence in the rDNA internal transcribed spacer (ITS) region of Kyu-W63 was compared with that of Irpex lacteus, which is known to produce these substances. Strain Kyu-W63 completely agreed with I. lacteus in terms of the ITS sequences, so strain Kyu-W63 was inferred to be I. lacteus. Two other strains of I. lacteus tested also produced the two furaldehydes and suppressed the growth of F. oxysporum f. sp. lycopersici. Both Kyu-W63 and additional strains produced the two furaldehydes on potato dextrose agar but not on water agar.The nucleotide sequence data reported are available in the DDBJ databases under accession numbers AB079264, AB079265, AB079266, and AB079267     

一株橡胶树白粉病生防菌的鉴定及在橡胶树叶片定殖规律研究

从橡胶树根际土壤中分离到一株对橡胶树白粉病(Oidium heveae)有较强拮抗作用的细菌S43,对其进行形态、生理生化特征以及gyrB基因序列分析,将S43鉴定为枯草芽胞杆菌(Bacillus subtilis).采用伤叶和不伤叶的方法,研究了标记菌株S43*在橡胶叶片中的定殖动态.结果表明:S43*能在橡胶树叶片上较好地定殖,接种后第1天菌量达到最大为1.34×105cfu/g,随着时间推移标记菌株在叶片定殖数量呈总体下降趋势,接种15d后达到稳定,为1.9×102 cfu/g.     

豌豆离体叶片鉴定白粉病抗性方法

1997～2001年对豌豆离体叶片鉴定白粉病抗性方法进行了研究。结果表明,将豌豆苗期离体叶片在垫有两层湿滤纸的培养皿内培养,并人工接种白粉病菌,能鉴定出豌豆品种抗白粉病的差异。鉴定结果与田间成株期的抗病性表现基本一致。温度、光照强度、叶龄、病菌接种量等因素影响离体叶片白粉病发生速度或保绿时间。离体鉴定较适宜在温度18～20℃、光照强度3600lx以上、每天12h光照与12h黑暗交替的条件下进行。最适叶龄为二叶一心期或三叶一心期的初展叶。较适宜的接种量为每1cm~2叶面积接种5.5×10~3个分生孢子。     

公主岭霉素对草莓的防病诱抗和促生效应

为明确公主岭霉素在草莓生产中的防病诱抗效应,于大田采用五点取样法调查公主岭霉素对草莓白粉病的防控效果及对植株生长性状的影响,并于室内采用生测法测定其对草莓叶片防御酶活性和根际土壤酶活性的影响。结果显示,以公主岭霉素水浸提液100倍稀释液进行灌根并协同叶面喷雾对草莓白粉病的预防效果为71.90%;单独叶面喷雾对草莓白粉病的治疗效果为69.90%;灌根协同叶面喷雾预防与叶面喷雾治疗的综合防控处理对草莓白粉病的防治效果可达85.37%。公主岭霉素水浸提液100倍稀释液灌根后草莓幼苗的株高、叶柄长、叶长、叶宽、叶数、径冠等方面均优于清水对照;叶面喷施可提升叶片中多酚氧化酶和超氧化物歧化酶的活性,喷雾后1 d内即较清水对照显著提高;5 d后过氧化氢酶活性显著高于清水对照。灌根后根际土壤中蔗糖酶的活性在用药后15 d内均显著高于清水对照。表明合理施用公主岭霉素可实现对草莓白粉病的有效防控,并诱导提升草莓植株的抗病性,改善草莓生长环境,促进其生长。     

南宁市桑白粉病病原菌种类鉴定

桑白粉病是桑树的重要病害,分为桑里白粉病和桑表白粉病。通过形态特征观察和ITS、D1/D2序列分析,明确桑里白粉病的病原菌为桑生球针壳Phyllactinia moricola;桑表白粉病的病原菌为桑白粉菌Erysiphe mori。桑钩丝壳Uncinula mori是桑白粉菌的异名。     

Role of stilbenes in the resistance of grapevine to powdery mildew

Stilbene phytoalexins are identified as defence response in pathogen–grapevine interactions, but little information is available on the role of stilbenes on Erysiphe necator, causal agent of grapevine powdery mildew. Analysis of stilbenes in artificially infected leaf discs from susceptible to highly resistant cultivars was performed and compared to the development of the pathogen. Results indicate that stilbene synthesis is confined in infected cells, penetrated by an appressorium–peg. Stilbene amounts expressed by infection site allow discriminating susceptible and resistant cultivars. Highest viniferins concentrations on resistant cultivars are in correspondence with the observed inhibition of the pathogen growth. The analysis of stilbenes at the infection site and viniferins accumulation in grapevine defence reaction is discussed.     

New tools for studying epidemiology and resistance of grape powdery mildew to DMI fungicides

Using a Random Amplified Polymorphic DNA (RAPD) assay, we investigated the genetic polymorphism existing among 62 European isolates of the grape powdery mildew fungus (Uncinula necator [Schw.] Burr.). Isolates overwintering as mycelium in buds were genetically distinct from isolates overwintering as ascospores, suggesting the existence of two genetically isolated powdery mildew populations, and consequently of two independent sources of inoculum in the vineyard. Isolates resistant to fungicides inhibiting sterol 14α-demethylation (DMIs) were found in both populations, suggesting that resistance to DMIs may arise independently in the two powdery mildew populations. A PCR assay targeting the gene encoding U. necator 14α-demethylase has been developed which will permit an early, specific detection of U. necator infections, and may be useful for spraying programmes. ©1997 SCI     

哈尔滨地区小天蓝绣球白粉病病原菌鉴定

小天蓝绣球Phlox drummondii Hook., 又名雁来红?金山海棠?福禄考, 是一种极具观赏性的一年生草本植物, 在我国北方被用来城市绿化?在小天蓝绣球的生长过程中, 白粉病已成为其所患病害中发生最为严重的一种, 给小天蓝绣球产业造成了巨大的损失, 也使其丧失了美化城市的功能?本研究以东北农业大学园艺实验站的小天蓝绣球病叶为材料, 对其病原菌进行形态学和分子生物学鉴定, 明确其分类地位, 为小天蓝绣球白粉病的科学防治提供依据?结果表明:小天蓝绣球白粉病菌主要侵染叶片, 叶片正面布满白色粉层, 后期叶片上产生黑褐色的小点, 即闭囊壳?闭囊壳直径80~160 μm, 附属丝菌丝状, 长度30~210 μm, 子囊多个, 一个子囊内含有子囊孢子2~8个, 分生孢子为粉孢子?对病原菌的ITS序列进行PCR扩增, 得到561 bp的序列(GenBank登录号:MN209867), 在GenBank上进行BLAST比对, 确定此病菌为Golovinomyces magnicellulatus?     

采用孢子萌发法测定化合物对黄瓜白粉病菌的生物活性

接种黄瓜白粉菌后16 h的黄瓜叶片用透明胶带在子叶表面粘孢子取样的平均发芽率与用台盼蓝染色后在光学显微镜下调查的发芽率分别为83.7%和85.0%,t测验无显著差异,表明透明胶带取样的发芽率可以代表黄瓜叶片上白粉病菌孢子的发芽率。采用孢子萌发法和叶碟法分别测定了醚菌酯、植物源活性组分大黄素甲醚(P3D)对8个黄瓜白粉菌菌株的EC₅₀。统计结果表明:采用两种方法测定醚菌酯P、3D对黄瓜白粉菌的EC₅₀的相关系数的平方值分别为0.880、.99,表明两种方法的测定结果有很强的相关性;采用该孢子萌发法可评价化合物对植物专性寄生病菌如白粉菌孢子萌发的生物活性。     

Silicon induced resistance against powdery mildew of roses caused by Podosphaera pannosa

Powdery mildew, caused by Podosphaera pannosa, is a very common disease in greenhouse potted roses, resulting in poor marketing value and hence economic losses. Alternatives to chemical control are necessary, and therefore the ability of silicon (Si) applied to roots to control the disease was investigated, as well as the mechanisms behind the observed disease reductions. Four genotypes of miniature potted roses representing different genetic backgrounds and susceptibility to disease were studied. Plants were watered with a nutrient solution containing either 3·6 mm Si (100 ppm) supplied as K₂SiO₃ (Si+) or no Si (Si?) before inoculation with P. pannosa. Si application increased leaf Si content two‐ to four‐fold compared to control plants. Confocal microscopy showed that Si deposition was larger in Si+ than in Si? plants and that deposition mainly occurred in the apoplast, particularly in epidermal cell walls. Si application delayed the onset of disease symptoms by 1–2 days and disease severity was reduced by up to 48·9%. The largest reduction was found in the two most resistant genotypes, which also had the highest increase in Si uptake. The Si‐induced disease protection was accompanied by increased formation of papillae and fluorescent epidermal cells (FEC) as well as deposition of callose and H₂O₂, especially at the sites of penetration and in FEC, which are believed to represent the hypersensitive response. Si treatment reduced powdery mildew development by inducing host defence responses and can therefore be used as an effective eco‐friendly disease control measure.     

Differentiation of two powdery mildews of sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis>) by a PCR-mediated method based on ITS sequences

Powdery mildew can be found in most sunflower fields during the winter season in Taiwan and causes severe yellowing on the blade, petiole, stem, and calyx, as well as serious defoliation. Two types of powdery mildew fungi isolated from sunflower leaves showed variable status for fibrosin bodies. But only the cleistothecium of Podosphaera xanthii, one of the pathogens causing this disease, was observed on samples from Chungpu County at the beginning of 2005. With a species-specific primer pair, PN23/PN34, no specific PCR product was amplified from the pathogen’s genomic DNA. Based upon the ITS sequence of rDNA, three PCR primer sets (S1/S2, G1/G2, and L1/L2) specific to P. xanthii, Golovinomyces cichoracearum and Leveillula taurica, respectively, were designed to detect and differentiate pathogens causing powdery mildews on sunflower. Only the primer pairs S1/S2 and G1/G2 could amplify PCR products, with product sizes of 454 and 391 bp, respectively. Four samples of fungal DNA were subjected to a multiplex PCR amplification with primer pairs S1/S2 and G1/G2; P. xanthii and G. cichoracearum were successfully detected. These results suggest that the multiplex PCR method is a rapid, simple, and effective technique to detect and differentiate powdery mildews, for example P. xanthii and G. cichoracearum, found on sunflower. With morphologic characteristics, ITS sequence analysis and pathogenicity testing, P. xanthii and G. cichoracearum, the first case, are two powdery mildews on sunflower in Taiwan.     

小麦白粉病菌基因组DNA的微量提取及ISSR-PCR反应体系的优化

为了寻找适合小麦白粉菌基因组DNA微量提取的方法,本试验利用改进的CTAB法、电钻微量研磨一管法、FastPrep DNA试剂盒法和Chelex-100法分别提取小麦白粉菌基因组DNA。比较得出,在微量提取时,CTAB法的提取率较高;在分生孢子量较多时,FastPrep DNA试剂盒方法提取的DNA质量较高,这两种方法提取的DNA均适用于ISSR-PCR。采用正交设计L16(45)法优化了适合于小麦白粉病菌群体的ISSR体系,确定了25μL时优化的反应体系:1×buffer、模板DNA0.5ng、dNTP0.14mmol/L、TaqDNA聚合酶1U、引物1.4μmol/L、Mg2+1.8mmol/L。利用该体系筛选出了一批多态性较好的ISSR引物,为小麦白粉病菌遗传多样性研究奠定了基础。     

番茄白粉病田间扩展流行规律与药剂防治试验

通过2年对番茄白粉病田间扩展流行动态调查和药剂防治试验研究,结果表明：番茄白粉病菌首先由中心病株下部叶片向上部作垂直扩散,随后进行水平传播,且顺垄传播快;在甘肃省张掖市一般7月中旬至下旬开始出现,田间蔓延快;环境条件适宜时,从植株上部叶片显症到发病率达91.5%仅需5 d。田间防治试验表明,喷药7 d后,24%噻呋酰胺悬浮剂1 200倍液、15%三唑酮可湿性粉剂750倍液、30%苯醚甲环唑&#8226;丙环唑乳油2 000倍液和62.25%代森锰锌&#8226;腈菌唑可湿性粉剂600倍液防效达到最大,依次为83.4%、81.4%、81.3%和68.7%,而喷药10 d后40%氟硅唑乳油3个浓度梯度（3 000、5 000倍液和7 000倍液）的药效均达到最高值,依次为72.2%、73.3%和78.5%,表明40%氟硅唑乳油持效期较长,药效稳定。     

河南省西部山区小麦白粉菌群体遗传多样性分析

为揭示河南省小麦白粉菌群体遗传结构、起源及进化关系,采用简单重复序列区间(inter-simple sequence repeats,ISSR)和扩增片段长度多态性(amplified fragment length polymorphism,AFLP)分子标记技术对河南省西部山区4个小麦产区的35个小麦白粉菌单孢分离菌株进行了群体遗传多样性分析。结果显示:ISSR和AFLP分析均将35个菌株分为3个组,组Ⅰ包括来自卢氏和灵宝的大部分菌株;组Ⅱ包括来自栾川、卢氏和巩义的菌株;组Ⅲ由4个地区的个别菌株组成,同时包含1个闭囊壳释放子囊孢子获得的菌株。ISSR分析出菌株遗传距离分布在0.0139～0.6592之间,扩增多态性比率为64.83%,各菌株间的Shannon指数为0.2749;而AFLP分析所得的各菌株遗传距离变化幅度在0.1257～0.9322之间,扩增多态性比率为82.68%,各菌株间的Shannon指数为0.5100。可见,河南省小麦白粉菌具有丰富的遗传多样性,研究所用的2种方法均可用于遗传多样性分析,其中AFLP分析小麦白粉菌群体表现出更为丰富的遗传多样性。     

小麦抗白粉病基因在甘肃的有效性及评价

采自甘肃各地的小麦白粉菌株接种在含有已知抗白粉病基因的小麦品种(系)上,测定其毒性频率,并对这些品种进行了异地成株期抗性鉴定。根据已知抗病基因对白粉苗群体的抗性程度,对其进行抗性效能的评价。结果表明,Pml、Pm3c、Pm3f、Pm5、Pm6、Pm7、Pm8和Pm17在甘肃抗性差,已失去利用价值;Pm2、Pm3a、Pm3b、Pm19抗性较低,不宜单独作为抗源利用;Pm4b、Pm13、Pm20、Pm21和含有Pm4的白兔3号、肯贵阿1号及含有Pm“XBD”的我国农家品种小白冬麦抗性表现好,可作为抗性亲本利用。组合基因如Pm2 6、Pm2 Mld、Pml 2 9等都表现出较好的抗性,这表明利用抗源材料进行基因累加有望培育出优良的抗性品种。文中还结合抗源材料的农艺性状对其利用提出了建议。