Instituto de Biotecnología y Biología Molecular, CCT-La Plata, CONICET-UNLP, La Plata, Buenos Aires, Argentina.
J Biotechnol. 2011 Jan 10;151(1):151-8. doi: 10.1016/j.jbiotec.2010.11.007. Epub 2010 Nov 21.
The lack of naturally occurring resistance to Citrus psorosis virus (CPsV) has demanded exploitation of a transgenic approach for the development of CPsV-resistant sweet orange plants. Transgenic sweet orange plants producing intron-hairpin RNA transcripts (ihpRNA) corresponding to viral cp, 54K or 24K genes were generated and analyzed at the molecular and phenotypic levels. Two independent CPsV challenge assays demonstrated that expression of ihpRNA derived from the cp gene (ihpCP) provided a high level of virus resistance, while those derived from 54K and 24K genes (ihp54K and ihp24K) provided partial or no resistance. The presence of small interfering RNA molecules (siRNAs) in the ihpCP transgenic sweet orange plants prior to virus challenge, indicated that CPsV resistance was due to pre-activated RNA silencing, but siRNAs accumulation level was not directly correlated to the degree of the triggered virus resistance among the different lines. However, pre-activation of the RNA-silencing machinery and a certain minimum accumulation level of siRNA molecules targeting the viral genome are key factors for creating virus-resistant plants. This is the first report of resistance in citrus plants against a negative-strand RNA virus as CPsV.
柑橘疱叶病病毒（CPsV）缺乏天然抗性，因此需要采用转基因方法来培育抗 CPsV 的甜橙植株。我们生成并分析了产生病毒 cp、54K 或 24K 基因的内含子发夹 RNA 转录物（ihpRNA）的转基因甜橙植株，在分子和表型水平上进行了分析。两次独立的 CPsV 挑战试验表明，cp 基因衍生的 ihpRNA（ihpCP）表达可提供高水平的抗病毒抗性，而 54K 和 24K 基因衍生的 ihpRNA（ihp54K 和 ihp24K）则提供部分或无抗性。在病毒攻击之前，ihpCP 转基因甜橙植株中存在小干扰 RNA 分子（siRNAs），这表明 CPsV 抗性是由于预先激活的 RNA 沉默所致，但 siRNAs 积累水平与不同品系触发的病毒抗性程度没有直接相关性。然而，RNA 沉默机制的预先激活和针对病毒基因组的一定最小水平的 siRNA 分子积累是创建抗病毒植物的关键因素。这是首例关于柑橘植物对负链 RNA 病毒 CPsV 抗性的报道。
