Replicating potato spindle tuber viroid RNA is accompanied by short RNA fragments that are characteristic of post-transcriptional gene silencing

The low molecular weight fraction of tomato plants inoculated with potato spindle tuber viroid (PSTVd) contains a population of short PSTVd-specific RNAs of either polarity. The main constituents were RNAs of 22 and 23 nt representing different domains of the viroid genome. The occurrence of such distinct RNA species indicated that the nuclear replicating PSTVd RNA induces post-transcriptional gene silencing. The short RNAs were slightly more abundant at 30 days post-inoculation than at later stages and were present in plants infected with a mild, severe or lethal isolate of PSTVd. There was no apparent correlation between the quantity of small PSTVd-specific RNAs and the degree of virulence of the viroid isolate.

接种马铃薯纺锤块茎类病毒（potato spindle tuber viroid, PSTVd）的番茄植株的低分子量组分中，存在一类兼具正义与反义两种极性的PSTVd特异性短RNA群体。该组分的主要成分为长度22 nt与23 nt的RNA分子，它们对应类病毒基因组的不同结构域。这类特异性RNA物种的存在表明，在细胞核内复制的PSTVd RNA可诱导转录后基因沉默。此类短RNA在接种后30天的丰度略高于后续阶段，且在感染了PSTVd弱毒株、强毒株或致死毒株的植株中均可检出。PSTVd特异性小RNA的含量与类病毒分离株的致病力强弱并无明显相关性。