DEMETRA Department, University of Palermo, Viale delle Scienze Ed. 5, 90100 Palermo, Italy.
Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135, Torino, Italy.
J Gen Virol. 2012 Dec;93(Pt 12):2712-2717. doi: 10.1099/vir.0.045773-0. Epub 2012 Sep 12.
Tomato yellow leaf curl Sardinia virus and Tomato yellow leaf curl virus have co-existed in Italian tomato crops since 2002 and have reached equilibrium, with plants hosting molecules of both species plus their recombinants being the most frequent case. Recombination events are studied in field samples, as well as in experimental co-infections, when recombinants were detected as early as 45 days following inoculation. In both conditions, recombination breakpoints were essentially absent in regions corresponding to ORFs V2, CP and C4, whereas density was highest in the 3'-terminal portion of ORF C3, next to the region where the two transcription units co-terminate. The vast majority of breakpoints were mapped at antisense ORFs, supporting speculation that the rolling-circle replication mechanism, and the existence of sense and antisense ORFs on the circular genome, may result in clashes between replication and transcription complexes.
自 2002 年以来，番茄黄卷叶病毒和番茄黄曲叶病毒一直在意大利番茄作物中共存，并达到了平衡，最常见的情况是植物同时携带两种病毒的分子及其重组体。重组事件在田间样本和实验性共感染中进行研究，早在接种后 45 天就检测到重组体。在这两种情况下，重组的断点基本上不存在于对应 ORF V2、CP 和 C4 的区域，而在 ORF C3 的 3'末端区域密度最高，该区域靠近两个转录单元终止的区域。绝大多数的断点都定位于反义 ORF，这支持了这样一种猜测，即滚环复制机制，以及圆形基因组上存在的正义和反义 ORF，可能导致复制和转录复合物之间发生冲突。
