小麦黄花叶病毒低分子量RNA1的鉴定

Identification of a Low Molecular Weight Component of Wheat Yellow Mosaic Virus RNA1 in Infected Wheat

利用小麦黄花叶病毒(Wheat yellow mosaic virus, WYMV)潢川分离物连续继代机械接种感病小麦品种鄂恩1号,经继代接种12 代以上的小麦症状明显加重, Northern blot 检测发现一条明显的低分子量病毒RNA1(LMW RNA1),并在随后至26代的继代接种发病材料中稳定存在,但在利用同样病叶提纯的病毒粒子内检测不到LMW RNA1,表明其不能被包装到病毒粒子内。序列分析结果表明,低分子量RNA1 由病毒RNA1 发生内部缺失而产生,从RNA1 5′端非编码区(第68nt)到CI基因编码区的3′端(第2448nt)共缺失2380 个核苷酸,在缺失区域两端的结合位点存在六个碱基的正向重复序列CGTCTC。据此对此低分子量RNA1 的缺失机制进行了讨论,认为由一种模板转换机制导致了缺失的发生。

Repeated passage of several fungus-transmitted plant viruses can lead to sequence deletion in their hosts. In this paper, Northern blotting analysis revealed that a low molecular weight component of Wheat yellow mosaic virus(WYMV) RNA1 was detected after the twelfth passage of mechanical inoculation in wheat plants associated with exacerbate symptoms displayed and exist stably in the inoculated plants to the 26th passage in the experiment. However these low molecular weight RNAs could not be detected in the particles purified from the same infected samples, suggesting that they could not encapsidated in infected wheat. Sequence analysis showed that a contiguous segment of 2380 nucleotides(nt68 to nt2448) was internally deleted from the WYMV RNA1 and flanked by direct repeats of six nucleotides CGTCTC, which supports the “copy choice” model as the possible mechanism of the generation of this low molecular weight component of WYMV RNA1.