Taliansky M E, de Jager C P, Wellink J, van Lent J W, Goldbach R W
Department of Virology, Agricultural University, Wageningen, The Netherlands.
J Gen Virol. 1993 Sep;74 ( Pt 9):1895-901. doi: 10.1099/0022-1317-74-9-1895.
During an infection with cowpea mosaic virus (CPMV) both virion assembly and formation of tubules associated with plasmodesmata are required for cell-to-cell movement. These functions are encoded by the M-RNA of CPMV. To study the mechanism of CPMV movement, mutant N123 was used in complementation studies with sunn-hemp mosaic virus (SHMV), a legume-infecting tobamovirus. Previous studies have shown that N123 fails to spread in cowpea plants because of mutation(s) in its M-RNA. However, the mutant was efficiently replicated in cowpea protoplasts, in which virions were formed and tubular transport structures were induced. After high-dose inoculation of cowpeas with N123, only a few infected protoplasts could be isolated, indicating that cell-to-cell transport of N123 was greatly impaired, if not completely abolished. Upon coinoculation with SHMV, mutant N123 infected cowpea plants systemically and accumulated to levels which were comparable to those of wild-type CPMV. In contrast, separate B-RNA of CPMV and a CPMV deletion mutant lacking the tubule-inducing function, were complemented by SHMV to only low levels. It is concluded that SHMV-facilitated spread of CPMV in the non-virion tobamovirus mode is inefficient and that spread of mutant N123 is probably in the CPMV mode, SHMV providing an as yet unidentified helper function.
在感染豇豆花叶病毒（CPMV）期间，病毒粒子组装以及与胞间连丝相关的管状结构形成对于病毒的细胞间移动都是必需的。这些功能由CPMV的M-RNA编码。为了研究CPMV移动的机制，突变体N123被用于与感染豆科植物的烟草花叶病毒（SHMV）进行互补研究。先前的研究表明，N123由于其M-RNA中的突变而无法在豇豆植株中扩散。然而，该突变体在豇豆原生质体中能有效复制，在原生质体中形成了病毒粒子并诱导了管状运输结构。用N123高剂量接种豇豆后，只能分离出少数受感染的原生质体，这表明N123的细胞间运输即使没有完全被消除也受到了极大损害。与SHMV共同接种时，突变体N123能系统性地感染豇豆植株，并积累到与野生型CPMV相当的水平。相比之下，CPMV单独的B-RNA以及缺乏诱导管状结构功能的CPMV缺失突变体，只能被SHMV低水平互补。得出的结论是，SHMV以非病毒粒子烟草花叶病毒模式促进CPMV传播的效率很低，并且突变体N123的传播可能是以CPMV模式进行，SHMV提供了一种尚未明确的辅助功能。
