继代培养对链格孢菌生长及产毒的影响

目的 探究连续继代培养对链格孢菌(Alternaria alternata)菌株的生长以及产毒的影响。方法 将10株链格孢菌在马铃薯葡萄糖琼脂培养基(potato dextrose agar, PDA)上连续继代培养,分析菌株的生长、产孢情况;利用超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)检测并分析主要链格孢霉毒素[包括交链孢酚(alternariol,AOH)、交链孢酚单甲醚(alternariol monomethyl ether, AME)、交链孢烯(altenuene, ALT)、细交链格孢菌酮酸(tenuazonic acid, TeA)]的含量变化。结果 在PDA培养基中,连续继代培养链格孢菌极易出现角变、菌丝变白、菌丝生长速率加快等菌株退化现象。随着继代培养次数的增加,菌株生长速度加快,菌落直径变大,角变率增大;10株链格孢菌中有7株(MY-4、MY-12、MY-15、MY-73、MY-80、MY-103、MY-117)产孢量随着继代次...     

二氧化氯气体对葡萄链格孢菌的抑制作用

该文研究了二氧化氯气体(ClO 2)对链格孢菌的抑制作用,为降低采后葡萄贮藏过程中交链孢霉腐病带来的损失提供依据。用1.5、3.0、4.5、6.0、7.5、9.0μg/L ClO 2分别对离体链格孢菌处理10、20、30 min,以不做任何处理为对照组,通过测定菌落生长、孢子形成、芽管伸长抑制率及倒置显微镜观察菌丝形态来探究ClO 2对其抑制效果。并用3.0、6.0、9.0μg/L ClO 2对接种了链格孢菌的葡萄处理30 min,置于28℃的培养箱中贮藏,通过测定病斑直径、发病率及相关酶活性来探索ClO 2对交链孢霉腐病的抑制作用。结果表明,离体实验中,与对照组相比,ClO 2处理组均能显著抑制链格孢菌菌落生长、孢子形成及芽管伸长。且接种了链格孢菌的活体实验中,ClO 2处理组均能抑制果实的病斑直径及腐烂率,延缓果实中丙二醛含量的积累,维持较高的抗氧化活性,其中采用9.0μg/L ClO 2处理果实30 min效果最好。     

农抗TS99对烟草赤星病菌作用的研究

农用抗生素TS99对烟草赤星病菌具有明显的抗生作用.用稀释10倍的TS99粗提液处理后,菌体细胞膜被破坏,内含物外渗,原生质凝集,液泡消失,菌丝体产生瘤状畸形或断裂,其生长能力完全被抑制;20倍稀释液处理8d后,对菌丝生长的抑制率达85%,其产孢能力完全丧失.同时,TS99对孢子萌发也有持久的抑制作用,4倍稀释液能完全杀死孢子.     

防治烟草赤星病药效试验

为了更有效地防治烟草赤星病 ,用 7种药剂进行了大田喷施对比试验。结果表明 :4 0 %“菌核净”可湿性粉剂 5 0 0倍液、4 0 %“菌核铜”可湿性粉剂 5 0 0倍液、4 5 %“菌克”可湿性粉剂 5 0 0倍液、“云岭酶素”30 0倍液、4 5 %“金叶舒”可湿性粉剂 60 0倍液、3%“多抗霉素”可湿性粉剂 30 0倍液、30 %“大力”可湿性粉剂 5 0 0倍液的相对防效依次为 :92 .5 6%、92 .13%、92 .13%、91.18%、90 .36%、87.5 6%、85 .0 2 %、83.91% ,差异达显著水平     

氨基酸对烟草赤星病菌毒素毒性的影响

采用摩擦接种处理法、浇根处理法和发芽种子根处理法测定了烟草赤星病菌毒素的毒性,确定了烟草发芽种子根处理法作为烟草赤星病菌毒素毒性的测定方法.用8种氨基酸分别以5种不同浓度与烟草赤星病菌GL-6毒素混合接种,测定结果表明L-精氨酸、L-胱氨酸、L-谷氨酸、L-丙氨酸和L-天门冬氨酸所有供试浓度均增强病菌毒素毒性;而L-脯氨酸、L-色氨酸和L-缬氨酸对病菌毒素毒性有抑制作用,其有效浓度分别为0.02～0.2、0.02～0.2和0.02～2mg/mL.     

长柄链格孢(Alternaria longipes)和链格孢(A.alternata)的RAPD分析

对来自中国及亚、非、欧三大洲5个国家的10个烟草赤星病菌（Alternarialongies）及5个链格孢菌（A．alternata）标准菌株用6种随机引物（OPR01、OPR12、OPR13、OPR14、OPR15、OPK19）进行了基因组DNA随机扩增多态性分析，对RAPD带型所进行的聚类分析结果表明，所有参试菌株之间相似性很高（90．3％～94．7％），其系统聚类关系与寄主和地理来源没有相关性，证明A．longipes与A．alternata亲缘关系很近，建议将A．alternata确定为烟草赤星病菌的学名。     

几种药剂防治烟草赤星病的药效试验

为筛选出防治烟草赤星病的有效药剂,选取43%"戊唑醇"、40%"菌核净"、3%"多抗霉素"、80%"代森锰锌"、70%"甲基托布津"、75%"扑海因"、45%"抗赤星一号"等7种药剂,采用菌丝生长抑制法对烟草赤星病进行了室内毒力测定和田间药效试验.结果表明:室内试验中43%"戊唑醇"悬浮剂对供试病菌的毒力最强,EC50值最小,为0.0018 mg/mL,75%"扑海因"可湿性粉剂、40%"菌核净"可湿性粉剂、45%"抗赤星一号"可湿性粉剂、3%"多抗霉素"可湿性粉剂、80%"代森锰锌"可湿性粉剂、70%"甲基托布津"可湿性粉剂的毒力依次减弱,EC50分剐为0.0063、0.1597、0.1891、0.3835、1.755和9.1313mg/mL;室外试验中43%"戊唑醇"悬浮剂的防效最好,7种药剂防治效果依次为43%"戊唑醇"悬浮剂(2000倍液)＞40%"菌核净"可湿性粉剂(600倍液)＞75%"扑海因"可湿性粉剂(600倍液)＞3%"多抗霉素"可湿性粉剂(500倍液)＞45%"抗赤星一号"可湿性粉剂(800倍液)＞80%"代森锰锌"可湿性粉剂(500倍液)＞70%"甲基托布津"可湿性粉剂(700倍液).     

Effects of food preservatives on Alternaria alternata growth and tenuazonic acid production

The effects of different organic acids on Alternaria alternata growth and tenuazonic acid production (TeA) were evaluated. Both TeA pure toxin solution and TeA production in solid medium were considered. Sodium benzoate, potassium sorbate and sodium propionate, all preservatives commonly used by food industry in Argentina, were tested. TeA was stable as pure toxin solution when was treated with the salts of organic acids used. A differential effect was observed when the preservatives were evaluated in relation to A. alternata growth and TeA production in solid medium. L evels above 10mg/kg of sodium benzoate and potassium sorbate produced a total inhibition of fungal development and toxin biosynthesis. Sodium propionate produced a 59% decrease in A. alternata growth and total inhibition of TeA production only at the highest concentration of preservatives used.     

抗烟草赤星病的植物源粗提物筛选

为筛选对烟草赤星病有较高抗性的植物源提取物,进行了从10个科植物中以不同提取方法提取的12种粗提物对烟草赤星病室内孢子萌发和田间小区防治试验。结果表明:胡椒科的山鸡椒(Litseacubeba)果实的水蒸气粗提物、菊科的牛蒡(Arctiumlappa)种子的石油醚提取物和桃金娘科的丁子香(Syzygiumaromaticum)花的水蒸气粗提取物可明显抑制烟草赤星病菌孢子萌发,具有相对较好的田间防治效果。     

云南省烟草赤星病菌致病力分化及生物防治研究

从省内烟草种植区分离到烟草赤星病菌39株,利用离体叶片悬滴法,在感病品种RG17上进行致病力分化测定。结果表明,上述病菌的致病力按照病情指数可分为4种类型：即强、中、弱、不致病。从上述代表不同致病力的菌株中选取7株菌,采用对峙法与18株木霉菌对峙培养,从中筛选出一株对赤星病菌具极强拮抗作用的菌株TV-1。TV-1与赤星病菌的孢子混和液在PDA平板上的孢子萌发试验表明,TV-1不能抑制病菌孢子的萌发但能抑制其芽管的伸长。用TV-1制成的菌剂进行离体叶片、烟草苗期、大田期防效测定。结果表明：该菌剂为10^5个／mL时,具有抑制离体叶片病斑扩展的作用;浓度达10^7个／mL时,可明显防止病斑出现;同时它还能促进烟苗生长,其中苗期施用量,TV-1菌剂：营养土=1：15,促生效果显;苗期防猝倒病与对照相比防效达86．5％;大田营养袋亩施颗粒剂31kg、62kg,叶面喷施孢子液剂10^4个／mL4次,与对照相比对赤星病的防效分别高达60．57％、70．53％。     

安徽烟草赤星病菌生物学特性及致病力分化研究

研究了安徽地区烟草赤星病菌的生物学特性和致病力分化,结果表明,该菌在10～35℃条件下均能生长,最适生长温度为25～30℃,温度低于7℃或高于40℃菌丝不能生长;分生孢子致死温度是53℃5 min和50℃10 min,幼菌丝致死温度是52℃5min和49℃10 min.病菌在pH 4.0～11.0的范围内均能牛长,呈现双峰曲线,即在pH 6.0～pH 8.0生长较快,尤以pH 6.0和pH 8.0的条件下菌丝生长更快;分生孢子在pH 4.0～11.0之间均可以萌发;在pH 6.0时,产孢量最高.在光照和黑暗交替的条件下,有利于菌丝的生长和孢子产生.致病力测定结果表明,不同菌株之间致病力存在显著差异,根据接种K326烟草后所致病情指数的大小可供试菌株致病力划分为致病力强、中等、弱和不致病4种类型,说明安徽烟草赤星病菌存在明显的致病力分化;在不同烟区间和同一烟区内均存在不同致病力类型的菌株,致病力类型的分布与菌株地区来源有一定的相关.     

拮抗菌AM6代谢产物防治烟草赤星病试验

为开发更多的生物农药,进行了球孢链霉菌AM6代谢拮抗物质防治烟草赤星病试验。采用不同的施用浓度、不同的施用次数在自然发病条件下进行田间小区防效试验。结果表明,含有AM6拮抗物质的制剂喷雾烟草叶片对烟草赤星病有较好防治效果。其防效随制剂中拮抗物质含量的增加而提高,以100倍液施用2次防效较好,田间防效为80.3%;400倍液施用1次、2次和3次的防效分别为46.9%、64 9%和69.3%。含有AM6拮抗物质的制剂对烟草无明显药害。     

Effect of benzyl isothiocyanate on tomato fruit infection development by Alternaria alternata

Benzyl isothiocyanate (BITC) is known to be a strong antifungal compound in vitro against different fungi. The effectiveness of benzyl isothiocyanate to control Alternaria alternata growth in vitro and in vivo was tested. BITC in vitro activity was evaluated in A alternata growing on potato dextrose agar and exposed to 0.025, 0.05, 0.1, 0.2 or 0.4 mg ml^?1. In vivo activity was evaluated by exposing A alternata‐inoculated tomato fruits for either 18 or 36 h to 0.28 or 0.56 mg ml^?1 BITC packed on low‐density polyethylene film (LDPF) bags. Additionally, the effect of BITC on post‐harvest physiology and tomato quality throughout storage at 20 °C was evaluated daily by monitoring respiration rate and ethylene production, whereas total soluble solids, pH, titratable acidity and fresh weight loss were measured every 3 days. Results showed that the minimal inhibitory concentration of BITC in vitro was 0.1 mg ml^?1. A combined use of 0.56 mg ml^?1 BITC with LDPF for 18 h was the optimum treatment to control Alternaria rot in packed tomato fruit. No effect of BITC on respiration rate, ethylene production, total soluble solids, pH, weight loss and titratable acidity was observed. Results suggest that BITC can be used as a post‐harvest treatment to control Alternaria rot in tomato fruit without detrimental effects on the tomato post‐harvest quality. Copyright © 2005 Society of Chemical Industry     

银杏外种皮提取物对苹果链格孢霉的抑制作用

为研究银杏外种皮提取物（Ginkgo biloba exocarp extract,GBEE）对苹果链格孢霉的抑制作用,采用乙醇提取法和水提取法提取银杏外种皮活性成分,并采用菌丝生长速率法,测定银杏外种皮提取物对苹果链格孢霉的抑制效果,研究银杏外种皮乙醇提取物对苹果链格孢霉孢子萌发和芽管伸长的影响。通过测定电导率,蛋白质、核酸的渗漏量,细胞膜损伤程度以及抗性相关酶活性来进一步研究抑制行为。GBEE的抑菌作用呈浓度依赖性,水溶性提取物于1 200 mg/L抑菌率达到16.94%,乙醇提取物于1 200 mg/L抑菌率达到61.39%,约为水溶性提取物的3.6倍。银杏外种皮乙醇提取物使苹果链格孢霉菌体细胞膜通透性增加,膜脂过氧化程度加剧,丙二醛（malondialdehyde,MDA）和H2O2含量升高,胞内核酸、蛋白质外泄,抑制抗性相关酶活性,通过光学显微镜观察到乙醇提取物处理组的链格孢霉菌无细胞壁间隔。乙醇提取物的抑菌效果比水提物好,通过破坏苹果链格孢霉菌的细胞膜完整性和抑制抗性相关酶活性来达到抑菌目的。     

Isotope fractionation of selenium during fungal biomethylation by Alternaria alternata

The natural abundance of stable Se isotopes may reflect sources and formation conditions of methylated Se. We aimed at (1) quantifying the degree of methylation of selenate [Se(VI)] and (hydro)selenite [Se(IV)] by the fungus Alternaria alternata at pH 4 and 7 and (2) determining the effects of these different Se sources and pH values on 82Se/76Se ratios (δ82/76Se) in methylselenides. Alternaria alternata was incubated with Se(VI) and Se(IV) in closed microcosms for 11-15 days and additionally with Se(IV) for 3-5 days at 30 °C. We determined Se concentrations and δ82/76Se values in source Se(VI) and Se(IV), media, fungi, and trapped methylselenides. In Se(VI) incubations, methylselenide volatilization ended before the 11th day, and the amounts of trapped methylselenide were not significantly different among the 11-15 day incubations. In 11-15 days, 2.9-11% of Se(VI) and 21-29% of Se(IV) were methylated, and in 3-5 days, 3-5% of Se(IV) was methylated. The initial δ82/76Se values of Se(VI) and Se(IV) were -0.69±SD 0.07‰, and -0.20±0.05‰, respectively. The δ82/76Se values of methylselenides differed significantly between Se(VI) (-3.97‰ to -3.25‰) and Se(IV) (-1.44‰ to -0.16‰) as sources after 11-15 days of incubation; pH had little influence on δ82/76Se values. Thus, the δ82/76Se values of methylselenide indicate the source species of methylselenides used in this study. The strong isotope fractionation of Se(VI) is probably attributable to the different reduction steps of Se(VI) to Se(-II) which were rate-limiting explaining the low methylation yields, but not to the methylation itself. The shorter incubation of Se(IV) for 3-5 days showed a large Se isotope fractionation of at least -6‰ before the biomethylation reaction reached its end. This initial Se isotope fractionation during methylation of Se(IV) is much larger than previously published.     

温度和叶面湿润时数对烟草赤星病菌侵染的影响

在控制条件下接种烟草赤星病菌的试验结果表明 ,在品种和菌株组成一定的情况下 ,接种温度 (DT)和叶面湿润时数 (WD)是影响病菌侵染的 2个主要因素。接种温度在 12～ 37℃范围内 ,病菌可以侵染寄主 ,成功侵染的最适温度为 2 7～ 30℃。在适宜温度条件下 ,接种后保湿 2h病菌即可侵入 ,保湿时间延长 ,侵染概率增大。侵染概率与接种温度、叶面湿润时数及其互作之间具有线性关系。     

楼葱中脂溶性成分提取及其对链格孢霉菌的抑制作用

以宁夏楼葱假茎部位为材料,采用酶辅助有机溶剂萃取法,通过正交试验优化楼葱中脂溶性物质的提取条件,并利用滤纸片法测定提取物对枸杞源链格孢霉菌的抑菌作用。结果表明：以乙酸乙酯作为萃取液时,楼葱脂溶性物质最佳提取条件为料液比1 ∶40（g/mL）、加酶量0.3%、酶解时间60 min、萃取时间36 h,该条件下楼葱脂溶性物质得率为（6.33±0.24）%。抑菌试验结果表明：在放置含提取物滤纸片的链格孢霉菌培养基中,抑菌圈直径为（19.58±0.31）mm,最小抑菌浓度为1.250 mg/mL,表明楼葱脂溶性提取物对枸杞源链格孢霉菌有较好的抑制作用。     

The influence of different nitrogen and carbon sources on mycotoxin production in Alternaria alternata

The aim of this study was to determine the influence of different carbon and nitrogen sources on the production of the mycotoxins alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by Alternaria alternata at 28 °C using a semi-synthetic medium (modified Czapek-Dox broth) supplemented with nitrogen and carbon sources. Additionally the effect of shaken and static cultivation on mycotoxin production was tested. Initial experiments showed a clear dependency between nitrogen depletion and mycotoxin production. To assess whether nitrogen limitation in general or the type of nitrogen source triggers the production, various nitrogen sources including several ammonium/nitrate salts and amino acids were tested. In static culture the production of AOH/AME can be enhanced greatly with phenylalanine whereas some nitrogen sources seem to inhibit the AOH/AME production completely. TA was not significantly affected by the choice of nitrogen source. In shaken culture the overall production of all mycotoxins was lower compared to static cultivation. Furthermore tests with a wide variety of carbon sources including monosaccharides, disaccharides, complex saccharides such as starch as well as glycerol and acetate were performed. In shaken culture AOH was produced when glucose, fructose, sucrose, acetate or mixtures of glucose/sucrose and glucose/acetate were used as carbon sources. AME production was not detected. The use of sodium acetate resulted in the highest AOH production. In static culture AOH production was also stimulated by acetate and the amount is comparable to shaken conditions. Under static conditions production of AOH was lower except when cultivated with acetate. In static cultivation 9 of 14 tested carbon sources induced mycotoxin production compared to 4 in shaken culture. This is the first study which analyses the influence of carbon and nitrogen sources in a semi-synthetic medium and assesses the effects of culture conditions on mycotoxin production by A. alternata.