玉米矮花叶病毒的株系鉴定

 从白草(Pennisetum flaccidum Griseb)花叶病株上分离到1个引起玉米矮化花叶症的新毒株。病毒粒体形态、大小、内含体形状,传染方式、传毒介体和传毒特性,体外抗性,寄主范围等生物学特性与MDMV-B相似,血清学上相关;白草花叶病毒分离物可侵染Paspa-lum dilatatum和Bromus rubens而不同于SCMV;根据在鉴别寄主忻粱7号和Atlas高粱上症状反应的显著差异可与MDMV-B相区别。据此认为它是MDMV的1个新株系,称为MDMV-G。1984年测定结果,玉米、高粱和谷子都感染MDMV-B和G,二者总的比例相近,山西各地均有分布,但高粱上G多于B,而玉米B多于G。白草是G株系的主要越冬寄主,广泛分布在山西省玉米、高粱栽培区,且自然感染率较高,对玉米和高粱的生产是个潜在的威胁,应予注意。白草在我国分布广泛,G株系的重要性可能不限于山西。

IDENTIFICATION OF STRAINS OF MAIZE DWARF MOSAIC VIRUS

A virus isolate which caused the Maize Dwarf Mosaic symptoms has been isolated from the infected Flaccid pennisetum(Pennisetum flaccidum).The viron is flexuous,375-750×13-14 nm.Pinwheel inclusion bodies were observed in the ultrathin sections of infected leaf.The virus was transmitted by mechanical means,as well as by vectors(Aphis gossypii,Rhopalosiphum padi and R.maidis) non-persistently;TIP 52-58℃,DEP 10^-4,LIV 3 days(room tempersture).Its host range is confined to the grass family with the exception of Johnson grass.All these characteristics showed that it is somewhat related to MDMV-B and the relationship was demomstrated serologically.This isolate was different from SCMV strains,because it infected Paspalum dilataum and Bromus rubens resulting in systemic mosaic symptoms.However,this virus isolate was different from MDMV-B by its conspicuous difference in symptoms on host cultivars such as Sorghums Xinli and No.7 and Atlas.
Therefore the isolate is considered to be a new MDMV strain,named MDMV-G or MDMV-Flaccid pennisetum.Maize,Sorghum and Millet are susceptible to MDMV-B and -G.Both strains can be found in various parts in Shanxi Province.Flaccid pennisetum is the main overwintering host of the G strain.