HOMOLOGY-DEPENDENT RESISTANCE - TRANSGENIC VIRUS-RESISTANCE IN PLANTS RELATED TO HOMOLOGY-DEPENDENT GENE SILENCING
HOMOLOGY-DEPENDENT RESISTANCE - TRANSGENIC VIRUS-RESISTANCE IN PLANTS RELATED TO HOMOLOGY-DEPENDENT GENE SILENCING
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DOI：
10.1046/j.1365-313x.1995.07061001.x
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发表时间：
1995-06-01
期刊：
影响因子：
7.2
通讯作者：
BAULCOMBE, DC
中科院分区：
文献类型：
--
作者：
MUELLER, E;GILBERT, J;BAULCOMBE, DC
先前已经描述了用马铃薯X病毒（PVX）的RNA聚合酶（RdRp）基因转化的对马铃薯X病毒感染具有极强抗性的烟草植物。PVX抗性植物积累的RdRp蛋白在较低的水平比完全易感植物转化相同的RdRp构建体。在本文中，PVX抗性和敏感的转化植物之间的差异进行了研究，它表明，有三个相关的表型的RdRp转基因的转化线之间平行变化。这些表型是：转基因RdRp RNA以低水平积累;对PVX的菌株特异性抗性;以及转基因转同源转基因的能力。通过对极耐PVX的一个杂种和第二个PVX敏感杂种的杂交后代的分析，说明了赋予PVX抗性的转基因的这种基因沉默潜力。在其他转化体中，其中的电阻是不太极端，相同的三个表型相关联，但在转基因剂量依赖性的方式。菌株特异性抗性和转基因RdRp RNA的低水平积累的相同关联与用RdRp基因的突变体或野生型版本转化的植物一起观察到。株系特异性抗性也产生在转化了不可翻译版本的RdRp转基因的植物中。基于这些数据，提出同源性依赖的基因沉默和转基因抗PVX可能是由于相同的RNA为基础的机制。一个未定义的基因组功能，提出占不同的转化体的抗性和反式失活表型的变化。进一步提出，该基因组特征影响降解与沉默转基因具有序列同源性的RNA的细胞质机制。
Tobacco plants transformed with the RNA polymerase (RdRp) gene of potato virus X (PVX) that are extremely resistant to infection by potato virus X have previously been described. The PVX-resistant plants accumulated the RdRp protein at a lower level than fully susceptible plants transformed with the same RdRp construct. In this paper the difference between the PVX-resistant and susceptible transformed plants is investigated and it is demonstrated that there are three associated phenotypes of the RdRp transgene that vary in parallel between transformed lines. These phenotypes are: accumulation of the transgenic RdRp RNA at a low level; strain-specific resistance to PVX; and the ability of the transgene to trans-inactivate homologous transgenes. This gene-silencing potential of the transgenes conferring PVX resistance was illustrated by analysis of progeny from a cross between a transformant that was extremely resistant to PVX and a second PVX-susceptible transformant. In other transformants, in which the resistance was less extreme, the same three phenotypes were associated but in a transgene dosage-dependent manner. The same association of strain-specific resistance and low-level accumulation of the transgenic RdRp RNA was observed with plants that were transformed with mutant or wild-type versions of the RdRp gene. Strain-specific resistance was also produced in plants transformed with untranslatable versions of the RdRp transgene. Based on these data it is proposed that homology-dependent gene silencing and transgenic resistance to PVX may be due to the same RNA-based mechanism. An undefined genomic feature is proposed to account for the variation in the resistance and trans-inactivation phenotypes of different transformants. It is further proposed that this genome feature influences a cytoplasmic mechanism that degrades RNA with sequence homology to the silencing transgene.