MUTATIONAL ANALYSIS OF THE MONOPARTITE GEMINIVIRUS BEET CURLY TOP VIRUS
MUTATIONAL ANALYSIS OF THE MONOPARTITE GEMINIVIRUS BEET CURLY TOP VIRUS
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DOI：
10.1016/0042-6822(92)90201-y
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发表时间：
1992-11-01
期刊：
影响因子：
3.7
通讯作者：
MARKHAM, PG
中科院分区：
文献类型：
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作者：
STANLEY, J;LATHAM, JR;MARKHAM, PG
甜菜曲顶病毒单分型双生病毒突变体在本氏烟草和甜菜上的感染性和症状发展，在N. benthamianaleaf光盘，并通过叶蝉Circulifer tenellus传播。通过引入终止密码子破坏开放阅读框（ORF）V2导致N. benthamiana与低水平的病毒和减少单链（as）DNA相关，并防止B.普通的N中的突变体产生的ssDNA水平降低。benthamianaleaf光盘，表明V2影响这种病毒DNA形式的合成或积累。突变体，其中ORF C2已被截断的终止密码子的引入或移码仍然高度传染性和诱导严重的症状，在bothN。benthamianaandB.普通的类似地，在ORF C3内含有终止密码子的突变体在N中具有高度感染性并诱导严重症状。benthamianaB. vulgaris大大减少，症状非常轻微，病毒水平很低。ORFs C2和C3中的双重突变的协同效应，表现为突变体不能全身感染N。benthamiana和生产量减少ssDNA在N. benthamianaleaf discs，表明两个ORF在该宿主中都有功能。在ORF C4的5′端含有终止密码子的突变体在两个N中都产生了严重的症状。benthamianaandB. vulgaris类似于由野生型病毒诱导的那些。与先前表征的ORF C4突变体的表型的比较表明，该ORF的保守核心序列是一个重要的症状决定因素。ORF C2、C3和C4突变体产生病毒颗粒并通过C. tenellus，消除农杆菌接种作为突变体表型的贡献因素。我们的研究结果进行了比较，来自相关的二分双生病毒的诱变研究。
Mutants of the monopartite geminivirus beet curly top virus have been screened for infectivity and symptom development inNicotiana benthamianaandBeta vulgaris, for replication competence inN. benthamianaleaf discs, and for transmission by the leafhopperCirculifer tenellus. Disruption of open reading frame (ORF) V2 by the introduction of a termination codon resulted in symptomless infection ofN. benthamianaassociated with low levels of virus and reduced single-stranded (as) DNA and prevented systemic infection ofB. vulgaris. Reduced levels of ssDNA were produced by the mutant inN. benthamianaleaf discs, suggesting that V2 affects the synthesis or accumulation of this viral DNA form. Mutants in which ORF C2 had been truncated by the introduction of termination codons or by frame-shifting remained highly infectious and induced severe symptoms in bothN. benthamianaandB. vulgaris. Similarly, a mutant containing a termination codon within ORF C3 was highly infectious and induced severe symptoms inN. benthamianaalthough infectivity inB. vulgariswas greatly reduced, symptoms were extremely mild, and virus levels were low. A synergistic effect of a double mutation in ORFs C2 and C3, manifested by the inability of mutants to systemically infectN. benthamianaand the production of reduced amounts of ssDNA inN. benthamianaleaf discs, suggests that both ORFs are functional in this host. A mutant containing a termination codon within the 5′ terminus of ORF C4 produced severe symptoms in bothN. benthamianaandB. vulgarisresembling those induced by wild-type virus. Comparison with the phenotypes of previously characterized ORF C4 mutants suggests that a conserved core sequence of this ORF is an important symptom determinant. ORF C2, C3, and C4 mutants produced virus particles and were transmitted byC. tenellus, eliminating agroinoculation as a contributory factor to the mutant phenotypes. Our results are compared with those derived from mutagenesis studies on related bipartite geminiviruses.