Kaplan I B, Palukaitis P
Department of Plant Pathology, Cornell University, Ithaca, New York, 14853, USA.
Virology. 1998 Nov 25;251(2):279-87. doi: 10.1006/viro.1998.9422.
Defective mutants of cucumber mosaic virus (CMV) RNA 3, containing deletions in the 3a gene were passaged in transgenic tobacco plants expressing the CMV 3a gene. After six passages, the various progeny RNA 3 were characterized. In all but one case, the size of the deletion increased. For the NheI-fs RNA 3 mutant of the Fny-strain of CMV (with an 8 nucleotide deletion), the deletion increased in the progeny viral RNA 3 to 570 nucleotides. For a similar frameshift mutant in RNA 3 of the M strain of CMV, either single RNA 3 species (with deletions of 579 or 627 nucleotides) or mixtures of RNA 3 deletion variants were observed in different plants. The DeltaE-H mutant (with a deletion of 202 nucleotides) of Fny-CMV RNA 3 underwent further deletion resulting in the loss of the entire 3a gene and flanking sequences. The DeltaKpnI mutant (deletion of 501 nucleotides) of Fny-CMV RNA 3 underwent a further deletion of 30 nucleotides. Except for the deletion progeny of the DeltaE-H RNA 3 mutant, the other defective RNA 3s all contained inframe deletions. It is proposed that the various deletions were created by different types of recombination and that packaging may be an important factor in the selection of particular defective RNA 3 variants.
黄瓜花叶病毒（CMV）RNA 3的缺陷型突变体，其3a基因存在缺失，在表达CMV 3a基因的转基因烟草植株中传代。传代六次后，对各种子代RNA 3进行了表征。除了一个案例外，在所有其他案例中，缺失的大小都增加了。对于CMV Fny株系的NheI-fs RNA 3突变体（有8个核苷酸的缺失），子代病毒RNA 3中的缺失增加到了570个核苷酸。对于CMV M株系RNA 3中的类似移码突变体，在不同植株中观察到了单一的RNA 3种类（有579或627个核苷酸的缺失）或RNA 3缺失变体的混合物。Fny-CMV RNA 3的DeltaE-H突变体（有202个核苷酸的缺失）进一步缺失，导致整个3a基因和侧翼序列丢失。Fny-CMV RNA 3的DeltaKpnI突变体（缺失501个核苷酸）又进一步缺失了30个核苷酸。除了DeltaE-H RNA 3突变体的缺失子代外，其他有缺陷的RNA 3都包含框内缺失。有人提出，各种缺失是由不同类型的重组产生的，并且包装可能是选择特定缺陷RNA 3变体的一个重要因素。
