A leaf spot on pepper caused by Cladosporium oxysporum has increasingly caused economic *** objective of this study is to observe the infection process of *** on the leaves of one susceptible pepper cultivar with ligh...
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A leaf spot on pepper caused by Cladosporium oxysporum has increasingly caused economic *** objective of this study is to observe the infection process of *** on the leaves of one susceptible pepper cultivar with light and scanning electron *** infectious stage started with conidium germination 8h after inoculation(hai),subsequently germinated hyphae grew over and along stomata by 24 *** 36 hai appressoria had been observed at the tips of *** usually occurred on the third or fourth day after inoculation(dai).Runner hyphae did not show directional growth towards *** often hyphae were growing over stomata without entering *** the hyphae penetrated without formation of an appressorium,directly or by means of a side *** 7 dai conidiophores emerged through the stomata and produced *** is the first time that *** has been reported to infect pepper leaves in the laboratory setting,on which germination of conidia,appressoria,conidiophores and conidium production are successively observed.
Aspergillus niger,a genus of filamentous fungus found in soil,was investigated for production of nematicidal *** this end,*** isolate y-61 was grown in Czapek-Dox medium,and culture broth filtrate was tested for activ...
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Aspergillus niger,a genus of filamentous fungus found in soil,was investigated for production of nematicidal *** this end,*** isolate y-61 was grown in Czapek-Dox medium,and culture broth filtrate was tested for activity against the nematodes Meloidogyne incognita(root-knot nematode).Oxalic and citric acids,were isolated based on bioassay-guided fractionation of culture filtrates against *** median lethal concentrations(LC) at 24 h were 74.2mg/L and9024.3mg/L against ***,respectively.
镰孢菌(Fusarium spp.)可以引起两种小麦病害,即小麦赤霉病(Fusarium head blight,FHB)和小麦茎基腐病(crown rot,CR)。这两种病害主要在发病部位和发病时期有所不同,但都可以引起严重的小麦产量损失,并且病原菌产生的单端孢霉烯族(tric...
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镰孢菌(Fusarium spp.)可以引起两种小麦病害,即小麦赤霉病(Fusarium head blight,FHB)和小麦茎基腐病(crown rot,CR)。这两种病害主要在发病部位和发病时期有所不同,但都可以引起严重的小麦产量损失,并且病原菌产生的单端孢霉烯族(trichothecene)毒素对人畜的健康造成很大威胁。在我国,引起小麦赤霉病和小麦茎基腐病的镰孢菌种群主要是***和***,且以***种群为主。根据产毒素的种类可分为3种不同的化学型:产脱氧雪腐镰孢菌烯醇(DON)和3-乙酰脱氧雪腐镰孢菌烯醇(3-AcDON)的3-AcDON型、产脱氧雪腐镰孢菌烯醇(DON)和15-乙酰脱氧雪腐镰孢菌烯醇(15-AcDON)的15-AcDON型和产雪腐镰孢菌烯醇(NIV)的NIV型。本研究采用小麦扬花期单花滴注接种法对小麦赤霉和小麦茎基腐病菌的致病力进行了测定。结果表明,35株小麦赤霉病菌的平均发病小穗数为5.6,40株小麦茎基腐病菌的平均发病小穗数为4.7。方差分析的结果表明小麦赤霉病菌与小麦茎基腐病菌的致病力差异不显著(P=0.27)。20株产3-AcDON化学型的小麦赤霉菌株平均发病小穗数为16.4,20株产15-AcDON化学型的小麦赤霉菌株平均发病小穗数为15.0,20株产NIV化学型的小麦赤霉菌株平均发病小穗数为8.2,方差分析结果表明,3-AcDON化学型的小麦赤霉菌株和15-AcDON化学型的小麦赤霉菌株的致病力差异不显著,NIV化学型的小麦赤霉菌株的致病力显著低于3-AcDON和15-AcDON化学型菌株。研究还进一步对不同化学型菌株的分生孢子形态进行了观察,并对不同化学型菌株的产孢能力进行了比较。
南方水稻黑条矮缩病毒(southern riee black streaked-dwarf virus,SRBSDV)属于呼肠孤病毒科(Reoviridae)斐济病毒属(Fijivirus)的一个暂定种,是近年来危害我国水稻生产的重要病毒之一。SRBSDV由介体白背飞虱以持久增殖型方式传播传播,...
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南方水稻黑条矮缩病毒(southern riee black streaked-dwarf virus,SRBSDV)属于呼肠孤病毒科(Reoviridae)斐济病毒属(Fijivirus)的一个暂定种,是近年来危害我国水稻生产的重要病毒之一。SRBSDV由介体白背飞虱以持久增殖型方式传播传播,病毒在昆虫体内的扩散直接关系到昆虫能否有效传播病毒。已知SRBSDV编码的P7-1非结构蛋白可独立形成管状结构,但功能未知,推测其与病毒的扩散有关。本研究在白背飞虱培养细胞内通过电镜切片观察到SRBSDV侵染后形成包裹病毒粒体的管状结构,免疫胶体金标记证明管状结构由P7-1蛋白组成。同时,包裹病毒粒子的管状结构可从侵染细胞伸向邻近的健康细胞,当通过人工合成的源于P7-1基因的dsRNA干扰P7-1蛋白的表达,不仅可抑制管状结构的形成,而且将病毒限制在初侵染细胞内,表明P7-1蛋白形成的管状结构参与病毒在细胞间的扩散。在昆虫体内,通过免疫荧光标记发现SRBSDV在初侵染的昆虫中肠上皮细胞内形成P7-1管状结构,管状结构可直接穿过上皮细胞以外的基底膜到达中肠表面的肌肉组织,随后通过与肌肉组织主要成分actin蛋白的互作沿着环肌和纵肌向其他器官扩散。当通过注射法将dsP7-1导入昆虫体内,不仅可以显著地抑制P7-1管状结构的形成,而且使病毒的复制局限在初侵染上皮细胞内,表明P7-1管状结构参与了病毒在昆虫体内的扩散。通过本研究系统地阐明了P7-1蛋白形成管状结构参与病毒的扩散,且管状结构可直接穿过基底膜突破昆虫的侵染屏障扩散到中肠表面,为解析SRBSDV与白背飞虱的高亲和性提供了理论依据。
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