小核菌中dsRNA的存在、位置及其生防作用

Scleortium cepivorum Berk．是引起洋葱白腐病的病原真菌，大部分测试的菌株含有dsRNA片段，这些dsRNA片段被称为真菌病毒。经琼脂糖凝胶电泳分析，在不同分离株之间或同一分离株不同提取物之间dsRNA带的数量和位置有很大的变化。ScQ-4菌株菌丝生长缓慢，致病力明显低于其他菌株。采用蔗糖密度梯度离心法证实和确定ScQ-4菌株中dsRNA片段所处的亚细胞位置，结果表明这些dsRNA片段与其寄主线粒体共同纯化，因此它们可能存在于寄主线粒体中，属于线粒体病毒。在营养相容性菌株之间这些dsRNA片段可通过菌丝融合进行传播，获得dsRNA片段的受体菌株的致病力明显降低，这对Sclerotium cepivorum Ber．k进行生物防治提供了可能性。

PRESENCE AND SUBCELLULAR LOCATION OF dsRNAs IN SCLFROTIUM CEPIVORUM AND BIOCONTROL STRATEGY OF THE PATHOGEN

Most tested isolates of Sclerotium cepivorum Berk., the causal agent of white rot of onion, contained detectable concentration of dsRNA segments, and both the number and position of bands of dsRNA detected by agarose gel electrophoresis varied among isolates and sometimes between extractions of the same isolate. We confirmed and determined the subcellular location of dsRNA segments in a severe diseased isolate using sucrose density centrifugation. The results revealed that these dsRNA segments copurify with the mitochondria of their fungal hosts, so they may reside in the mitochondria and belong to mitovirus. Transmission of the dsRNAs occurred among vegetative compatible isolates by hyphal anastomosis, thus it has opened up the possibility of biological control of the pathogen.