Hussain Mazhar, Mansoor Shahid, Iram Shazia, Zafar Yusuf, Briddon Rob W
National Institute of Biotechnology and Genetic Engineering, Faisalabad, Pakistan.
Mol Plant Microbe Interact. 2007 Dec;20(12):1581-8. doi: 10.1094/MPMI-20-12-1581.
The hypersensitive response (HR) is a common feature of plant disease resistance reactions and a type of programmed cell death (PCD). Many pathogens are able to modulate pathways involved in cell death. In contrast to animal viruses, inhibitors of PCD activity have not been identified for plant-infecting viruses. Previously, we have reported that the nuclear shuttle protein (NSP) of Tomato leaf curl New Delhi virus (ToLCNDV) induces an HR in Nicotiana tabacum and Lycopersicon esculentum plants when expressed under the control of the Cauliflower mosaic virus 35S promoter. However, HR is not evident in plants infected with ToLCNDV, suggesting that the virus encodes a factor (or factors) that counters this response. Analysis of all ToLCNDV-encoded genes pinpointed the transcriptional activator protein (TrAP) as the factor mediating the anti-HR effect. Deletion mutagenesis showed the central region of TrAP, containing a zinc finger domain and nuclear localization signal, to be important in inhibiting the HR. These results demonstrate that TrAP counters HR-induced cell death, the first such activity identified for a plant-infecting virus.
过敏反应（HR）是植物抗病反应的一个常见特征，也是一种程序性细胞死亡（PCD）。许多病原体能够调节参与细胞死亡的途径。与动物病毒不同，尚未鉴定出植物感染性病毒的PCD活性抑制剂。此前，我们报道了在花椰菜花叶病毒35S启动子的控制下表达时，番茄卷叶新德里病毒（ToLCNDV）的核穿梭蛋白（NSP）会在烟草和番茄植株中诱导HR。然而，在感染ToLCNDV的植株中HR并不明显，这表明该病毒编码一种（或多种）因子来对抗这种反应。对所有ToLCNDV编码基因的分析确定转录激活蛋白（TrAP）是介导抗HR效应的因子。缺失诱变表明TrAP的中央区域，包含一个锌指结构域和核定位信号，在抑制HR中很重要。这些结果表明TrAP对抗HR诱导的细胞死亡，这是首次鉴定出植物感染性病毒具有此类活性。
