Jones R W, Jackson A O, Morris T J
Department of Plant Pathology, University of California, Berkeley 94720.
Virology. 1990 Jun;176(2):539-45. doi: 10.1016/0042-6822(90)90024-l.
Tomato bushy stunt virus (TBSV) genomic RNA and one of its defective interfering (DI) RNAs were inoculated in various combinations to protoplasts of Nicotiana benthamiana. Ethidium bromide staining of electrophoretically separated RNAs from infected protoplasts, incorporation of [3H]uridine into TBSV and DI RNAs, and Northern hybridization at different times after inoculation clearly demonstrated reduced accumulation of genomic RNA in the presence of DI RNA. Accumulation of genomic RNA was very rapid between 3 and 9 hr postinfection. The presence of equimolar amounts of genomic and DI RNA in the inoculum resulted in a 65% suppression of genomic RNA accumulation. Suppression of genomic RNA was mediated by a reduction in the rate at which genomic RNA accumulated. Analysis of protoplasts inoculated with increasing ratios of DI:genomic RNA suggested that DI RNA-mediated suppression of genomic RNA synthesis results from competition for factors essential for viral replication. Incubation of protoplasts at different temperatures also had a profound effect on replication of both genomic and DI RNAs. Both replicated well at 27 degrees but were barely detectable at 32 degrees. Suppression of genomic RNA synthesis by DI RNA was similar at all temperatures tested. Thus, this study suggests that DI suppression of TBSV symptoms in whole plants and symptom attenuation at elevated temperatures are primarily the result of reduced viral replication.
将番茄丛生矮缩病毒（TBSV）基因组RNA及其一种缺陷干扰（DI）RNA以各种组合接种到本氏烟草的原生质体中。对感染原生质体经电泳分离的RNA进行溴化乙锭染色、将[3H]尿苷掺入TBSV和DI RNA以及在接种后不同时间进行Northern杂交，均清楚地表明在存在DI RNA的情况下基因组RNA的积累减少。感染后3至9小时之间，基因组RNA的积累非常迅速。接种物中存在等摩尔量的基因组RNA和DI RNA导致基因组RNA积累受到65%的抑制。基因组RNA的抑制是由基因组RNA积累速率的降低介导的。对接种了DI:基因组RNA比例不断增加的原生质体进行分析表明，DI RNA介导的基因组RNA合成抑制是由于对病毒复制所必需的因子的竞争所致。在不同温度下培养原生质体对基因组RNA和DI RNA的复制也有深远影响。两者在27℃时复制良好，但在32℃时几乎检测不到。在所有测试温度下，DI RNA对基因组RNA合成的抑制作用相似。因此，本研究表明，DI对全株TBSV症状的抑制以及在高温下症状的减轻主要是病毒复制减少的结果。
