水花生病原菌——蕉斑镰刀菌菌株的筛选及其致病性测定

蕉斑镰刀菌 Fusarium stoveri是从自然界水花生植株上分离的、可致水花生表现萎蔫、地上茎腐烂、叶片上呈现褐色斑或黄化的生防真菌.室内研究表明,蕉斑镰刀菌菌丝生长和产孢的适宜温度范围在25～28℃,多数菌株的最适温度为28℃;菌株间的产孢量有较大差异.在供试菌株中,32-6菌株的产孢量最大;供试的9个蕉斑镰刀菌菌株对水花生均有较强的致病力,但菌株间的致病力有所差异.根据菌株的生长速率、产孢量和致病力等因素,菌株32-6被选为水花生生防菌的优选菌株.采用生产上常见农作物、蔬菜、经济作物及物候上与水花生一致的杂草等42种植物对菌株32-6进行寄主专化性测定,结果表明,蕉斑镰刀菌菌株32-6具有高度的寄主专化性,只对水花生表现出较强的致病性,对其他植物均不致病.     

禾谷镰刀菌接种小麦幼芽及致病力鉴定的初步研究

 由镰刀菌引起的赤霉病是危害小麦、大麦、燕麦、黑麦等禾谷类作物的一种重要病害,广泛分布于世界温暖潮湿地区。在我国赤霉病发病区,禾谷镰刀菌(Fusarium graminearum Schwabe)是主要致病菌。     

提前接种非致病尖孢镰刀菌防治西瓜枯萎病试验

将尖孢镰刀菌203株菌系接种在西瓜苗上,从中选出非致病尖孢镶刀菌系109个,分3个类群。用有促生作用,能在西瓜导管定殖的10个代表菌系提前接种,经温室和田间试验,结果表明316和317菌系的防病效果最好。在土壤含枯萎菌量2％条件下,推迟发病7～10天。在土壤含病菌量0.01％条件下,接种后25天,交叉保护防效分别为34.6％和68.2％。防病效果随枯萎菌量的下降而提高。     

棉花枯萎镰刀菌致病力变异的研究Ⅱ.生理Ⅱ、Ⅲ型菌系异核现象的研究

 本研究是对棉花枯萎镰刀菌生理Ⅱ、Ⅲ型菌系的四个菌株用切割菌丝尖端和单孢分离的方法研究它们的异核现象。试验结果表明:在田间它们能以异核体存在,并有三种核型组成,通过对Ⅲ型菌系的野生异核体菌株及原生质融合异核体菌株进行致病力测定,致病力发生了变异,证明异核现象是Ⅲ型菌系致病力变异的重要因素之一。     

镰刀菌对大蒜根系分泌物的敏感性与其致病力相关分析

试验采用菌丝生长速率法测定了大蒜根系分泌物对3种供试植物病原镰刀菌的抑菌活性, 并进一步分析了18株从腐烂蒜瓣上分离的尖孢镰刀菌和12株从小麦赤霉病样分离的禾谷镰刀菌对大蒜根系分泌物的敏感性及致病力之间的关系。研究结果表明, 大蒜根系分泌物对供试镰刀菌均具有抑制活性, 但从腐烂蒜瓣上分离的尖孢镰刀菌对根系分泌物的敏感性低于其他菌株。致病力分析结果表明, 供试的18株尖孢镰刀菌均能使蒜瓣发病, 但致病力与其对根系分泌物的敏感性无明显相关性; 供试的禾谷镰刀菌中对根系分泌物不敏感的4株菌株能侵染蒜瓣, 但敏感性高的菌株不能侵染蒜瓣, 且根系分泌物对禾谷镰刀菌的抑制率与禾谷镰刀菌致病力之间呈显著的负相关。这表明大蒜根系分泌抑菌物质是根系抵御镰刀菌侵染的重要机制, 但一些菌株能对根系分泌物产生抗性, 从而侵染大蒜。综上所述, 大蒜根系分泌物对镰刀菌具有抑制活性, 可以利用大蒜和其他作物间作或轮作控制镰刀菌枯萎病的发生和蔓延, 但长期利用大蒜轮作或间作控制土传病害可能面临镰刀菌对大蒜根系分泌物产生抗性, 导致防效降低的风险。     

一种高效的镰刀菌接种体制备方法

本文以玉米茎腐病人工接种所需的禾谷镰刀菌Fusarium graminearum和拟轮枝镰刀菌F.verticillioides为材料,比较了三角瓶、聚乙烯袋和牛皮纸袋内用谷物培养基制备接种体的差别。发现在牛皮纸袋内用孢子悬浮液接种玉米粒培养基可高效制备接种体。与三角瓶、聚乙烯袋相比,在牛皮纸袋中制备接种体表现生长点多、透气性好、菌丝生长快、污染率低、质量高、对存放环境要求不严的优点。这种方法可以为玉米茎腐病等相似土传病害的人工接种和病圃建造等提供高质量的接种体。     

一种镰刀菌对空心莲子草的致病力与寄主专一性测定

从罹病的空心莲子草上分离到一种镰刀菌,人工接种条件下,3叶期的空心莲子草幼苗最易发病,叶部次之.在供试的4个菌株中,以YZ-03菌株的致病力最强,该菌株接种空心莲子草幼苗5d后,接种的植株病情指数已达100,8d后幼苗全部枯死;人工接种叶片和茎秆9d后,叶片的病情指数达90.95,接种茎秆的病情指数达85.19.采用27科61种植物对该镰刀菌进行寄主专一性测定,结果表明,该镰刀菌能使莲子草严重发病,也能侵染藜的幼苗,对包括主要农作物在内的其他59种植物均无致病性.     

培养条件对西瓜枯萎病菌镰刀菌酸产生的影响

 尖孢镰刀菌西瓜专化型[Fusarium oxysporum Sch l.f.sp.niveum(E.F.Smith) Snyder et Hansen]菌株在4种培养基(理查德培养基,Armstrong镰刀菌培养基,MS无机盐+蔗糖培养基,PDB培养液)中均能产生镰刀菌酸(Fusaric acid),理查德培养基中镰刀菌酸最高时的浓度是其它3种培养基的6~22倍。理查德培养基以C/N为5:1,葡萄糖为C源,NO-3为N源的营养条件较有利于镰刀菌酸产生。培养基初始pH值为4,通气和连续光照的培养条件最有利于菌株产生镰刀菌酸,烟酸的加入可终止镰刀菌酸产生。各培养基中孢子浓度与镰刀菌酸浓度之间呈负相关的变化趋势,培养基的pH值呈趋中(pH6~8)变化,与镰刀菌酸产生无相关性。在理查德培养基中,菌丝生长与镰刀菌酸产生之间存在平行关系。     

不同土壤湿度条件下绿色木霉对尖孢镰刀菌数量的影响

采用平板菌落计数法研究在不同土壤湿度条件下绿色木霉在土壤中的定殖动态及对尖孢镰刀菌数量的影响。结果显示：在3个土壤湿度条件下, 接种木霉后前4周均能显著降低镰刀菌的数量; 与对照2(CK-H06)相比, 处理(B2-H06)中木霉的孢子含量没有显著性变化。第1、2周, 对照1(CK-B2)与处理(B2-H06)的镰刀菌含量与土壤湿度呈显著性正相关; 在第5周, 处理(B2-H06)的镰刀菌和木霉菌含量与土壤湿度呈显著性负相关。     

镧素对镰刀菌Fusarium solani及其致病酶的影响

采用琼脂平板生长速率法及液体培养基培养测定了La对镰刀菌Fusarium solani的抑制作用和毒力,并测定了其对病菌胞外的果胶酶、蛋白酶和纤维素酶等几种致病酶活性的影响。结果表明,随着La2O3浓度升高,对病菌菌丝生长的抑制作用增强,对病菌的EC50和EC95分别为278.2和552.0 mg/L;在一定浓度范围内,La提高了单位量菌丝所产生3种致病酶的活性,但由于菌丝生长受到抑制,除蛋白酶外,病菌胞外致病酶果胶酶和纤维素酶的总量或总活性受到了抑制,降低了病菌的致病力。     

假隔链格孢SF-193的产孢特性及其分生孢子对空心莲子草的致病力

为了探明SF-193的产孢特性,选取了8种产孢培养基,研究分别在自然光、黑光灯和黑暗的条件下对SF-193产孢的影响程度。试验结果表明,在黑光灯连续照射11d后,SF-193在PCA、CA、SNA、Czapek和组织煎汁5种培养基上有少量分生孢子产生,而在其他3种琼脂培养基上不产生分生孢子。PCA培养基中马铃薯与胡萝卜比例为1：5时,SF-193在9d后产孢量最大,10×10倍显微观察约60个孢子/视野;当CA培养基中的胡萝卜含量提高至80%左右时, SF-193在3d后达到最大产孢量,10×10倍显微观察约300个孢子/视野。研究了黑光灯照度与胡萝卜含量对SF-193产孢的影响。结果表明,在黑光灯照度为195～210lx、胡萝卜含量约为0.8g/ml时,SF-193在25℃培养6d后产孢量最大,约为6.5×10^5个孢子/ml。SF-193的分生孢子在田间对空心莲子草的致病力测定结果表明,经孢子浓度10^4个孢子/ml处理后,空心莲子草的病情指数为67.7。     

空心莲子草生物防除研究进展

空心莲子草(Alternanthera philoxeroides)是一种全球性的恶性入侵杂草.本文总结了国内外空心莲子草生物防除的研究进展.主要包括病原真菌假隔链格孢菌(Nimbya alternantherae)和空心莲子草叶甲(Agasicles hygrophila)等生防作用物防除空心莲子草的研究进展和现状.     

两种生境条件下空心莲子草叶片解剖结构比较

通过扫描电子显微镜和光学显微镜的观察比较，发现空心莲子草在水生和旱生两种生境下叶片组织的形态结构有较大的差异，这说明空心莲子草具有在不同的生境中组织形态结构会发生相应变化的特点，这可能是空心莲子草能在不同生境条件下迅速扩散的原因之一。     

生防菌SF-193对空心莲子草防除效果及其影响因子的研究

摘要：在室内控制条件下，测定了SF-193菌株培养液对空心莲子草的致病力；在田间小区试验的条件下，测定了SF-193对空心莲子草的防除效果，以及不同因子对SF-193除草效果的影响程度。结果表明，SF-193培养3～5d的培养液具有最强的致病力；最佳接种体为含有菌丝体的培养液；田间有效接种浓度为10倍稀释液，室内有效接种浓度为25倍稀释液；适宜SF-193对空心莲子致病的最佳温度为25～30％；高湿条件下SF-193致病过程加快。SF-193对不同生长季节和不同生境下的空心莲子草均有较好的防除效果。     

Pathogenicity and toxicity of Fusarium tucumaniae and Fusarium crassistipitatum to soybean and Arabidopsis thaliana

Sudden death syndrome (SDS) of soybean is a fungal disease caused by at least four distinct Fusarium species: F. tucumaniae, F. virguliforme, F. brasiliense, and F. crassistipitatum. All four species are present in Argentina. These fungi are soilborne pathogens that only colonize roots and cause root necrosis. However, damage also reaches the aboveground part of the plant, and foliar chlorosis and necrosis, followed by premature defoliation, can be observed. Although the pathogenicity and phytotoxicity of F. virguliforme has been well characterized, knowledge regarding disease development by other fungal species is scarce. In this study, two plant species, soybean (Glycine max) and Arabidopsis thaliana, and isolates from two fungal species, F. tucumaniae and F. crassistipitatum, were used to comparatively analyse the fungal pathogenicity and the phytotoxicity of volatile organic compounds (VOCs) and cell-free culture filtrates. Fungal inoculation had a significant effect on plant growth, regardless of the plant species. In addition, infected soybean plants showed disease incidence and foliar and root symptoms. Inhibition of A. thaliana growth was not due to VOCs emitted by fungi. Instead, both pathogens were shown to produce toxins that caused typical SDS foliar symptoms in soybean and root length reduction in A. thaliana. As far as we know, this is the first report that demonstrates that F. tucumaniae and F. crassistipitatum affect A. thaliana growth and emit VOCs, and that F. crassistipitatum produces toxins.     

木贼镰刀菌的鉴定及其对桃蚜的致病性测定

从罹病桃蚜虫尸上分离到了一株昆虫病原真菌,命名为JMF-01,本文旨在确定该菌株分类地位并探索其生防潜能。对罹病的桃蚜虫尸进行分离纯化,基于形态学观察和r DNA-ITS、RPB2、IGS序列分析,构建系统发育树对该菌株进行鉴定。采用浸叶浸虫法研究该菌株不同浓度条件下对桃蚜的致病力并进行温室防效测定。结果表明菌株JMF-01在PDA培养基上5 d后菌落直径58～60 mm,分生孢子镰刀形,3～7隔。菌株JMF-01对桃蚜具有较强致病力,处理桃蚜在7 d后累计校正死亡率和LC₅₀达到85%和9.87×10⁵cfu/mL;孢子悬浮液最高浓度的温室防效在14 d时高于70%。该菌株的r DNA-ITS序列(MW404610)与木贼镰刀菌Fusarium equiseti(Gen Bank登录号：JF773657)相似度达100%,位于系统发育树的同一分支;RPB2、IGS序列分别与木贼镰刀菌(GenBank登录号：MK077112,KX583611)的相似度也达到99%以上,聚在系统发育树的同一分支。菌株JMF-01经鉴定为桃蚜的病原真菌木贼镰刀菌...     

Sexual recombination of carbendazim resistance in Fusarium graminearum under field conditions

BACKGROUND: Carbendazim has been the major fungicide for control of Fusarium head blight (FHB) caused by Fusarium graminearum Schwade in China. However, the effectiveness of carbendazim has been threatened by the emergence of resistant pathogen populations in the field. RESULTS: Five isolates, representing three phenotypes of different carbendazim sensitivity levels (S, MR and HR), were randomly selected to study the inheritance of carbendazim resistance by three genetic crosses under field conditions. Each parent in all crosses was marked with a different class of nitrate non‐utilizing (nit) mutation. The presence of sexual recombinants indicated that outcrossing had occurred in the crosses. Over 100 putative self‐crossing or outcrossing perithecia for each cross were randomly sampled on the surface of the haulms of dead rice for each pair of parents. Results showed that 5.7–20.9% outcrossing frequency occurred in the three crosses and confirmed sexual recombination under field conditions. There were no significant differences in mycelial linear growth and pathogenicity between the selected recombinants and their parents, but they differed in sporulation ability and capacity to produce perithecia. Nevertheless, most of the sexual recombinants possessed fitness levels comparable with those of their parents. CONCLUSION: Outcrossing between carbendazim‐sensitive and ‐resistant isolates did occur under field conditions, and sexual recombination must play a role in the development of carbendazim resistance in the field. Copyright © 2009 Society of Chemical Industry     

Pathogenicity of Fusarium solani f.sp. cucurbitae race 1 to courgette

Fusarium solani f. sp.cucurbitae race 1 causes foot rot in courgette (Cucurbita pepo). The pathogen could be distinguished fromFusarium solani from sweet pepper (Capsicum annuum) both morphologically and in its host range.In inoculation experiments all nine cultivars of the six species of Cucurbitaceae tested were susceptible. Courgette Green became diseased after inoculation with a spore suspension by root dipping or adding the suspension to the soil around the stem base or spraying the whole plant with it.Both wounded and young plants died more quickly than unwounded and older plants. With low inoculum densities the plants were affected more slowly than with high densities and the differences in susceptibility of the Cucurbitaceae tested were more pronounced.From infected courgette seeds the fungus could be reisolated until 6 months after harvest.This is the first record of this pathogen in courgettes in the Netherlands.Samenvatting Fusarium solani f. sp. cucurbitae fysio 1 is de oorzaak van een voetrot in courgette. Het pathogeen is morfologisch en door middel van een waardplantenreeks goed vanF. solani uit paprika te onderscheiden.In inoculatieproeven waren de getoetste Cucurbitaceae in meer of mindere mate gevoelig voorF. solani f. sp.cucurbitae. Bij courgette Green werden zowel gedompelde, als aangegoten, als bespoten planten door het pathogeen aangetast. Zowel verwonde als niet-verwonde planten werden aangetast als ook planten van verschillende leeftijden. Niet-verwonde en ook oudere planten stierven minder snel af dan verwonde en jongere planten. Bij lagere inoculumdichtheden werden de planten minder snel aangetast dan bij hogere dichtheden en waren de verschillen in vatbaarheid voor het pathogeen tussen de getoetste Cucurbitaceae duidelijker.Uit courgette zaad, dat met het pathogeen was besmet, kon de schimmel tot 6 maanden na zaadwinning opnieuw worden geïsoleerd.Dit is de eerste melding van dit pathogeen in courgette in Nederland.