MAIZE STREAK VIRUS GENES ESSENTIAL FOR SYSTEMIC SPREAD AND SYMPTOM DEVELOPMENT
MAIZE STREAK VIRUS GENES ESSENTIAL FOR SYSTEMIC SPREAD AND SYMPTOM DEVELOPMENT
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DOI：
10.1002/j.1460-2075.1989.tb03469.x
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发表时间：
1989-04-01
期刊：
影响因子：
11.4
通讯作者：
ROGERS, SG
中科院分区：
文献类型：
--
作者：
LAZAROWITZ, SG;PINDER, AJ;ROGERS, SG
单组分双生病毒如玉米条纹病毒（MSV）的整个基因组由. apprx的单链环状DNA组成。2.7 KB.虽然这种大小足以编码仅三种平均大小的蛋白质，但该病毒能够引起许多单子叶植物的严重疾病，具有失绿和发育迟缓的症状。我们已经确定了MSV感染过程中系统传播和症状发展所必需的病毒基因功能。缺失和基因置换突变体是通过定点诱变和插入在农杆菌T-DNA衍生载体中所含的侧翼MSV或报告基因序列之间产生的。在农杆菌介导的玉米幼苗接种后，通过侧翼序列内的同源重组从这些二元载体中切除突变的MSV DNA。我们的分析表明，MSV的衣壳基因，而不是复制所需的，是必不可少的系统传播和随后的疾病发展。“+"链开放阅读框（ORF）位于衣壳ORF的上游，预测编码10.9 kd的蛋白质，也被发现是复制的必需品，但对系统传播是必需的。通过该分析，支持自主复制的MSV序列定位于包含两个病毒基因间区和两个重叠互补“-"链ORF的1.7kb片段。尽管基因置换突变体不能系统传播，接种和新开发的叶片显示类似于在某些发育突变体的玉米中观察到的表型褪绿模式。这些发育突变体的MSV突变表型的相似性进行了讨论。
The entire genome of single component geminiviruses such as maize streak virus (MSV) consists of a single-stranded circular DNA of .apprx. 2.7 kb. Although this size is sufficient to encode only three average sized proteins, the virus is capable of causing severe disease of many monocots with symptoms of chlorosis and stunting. We have identified viral gene functions essential for systemic spread and symptom development during MSV infection. Deletions and gene replacement mutants were created by site-directed mutagenesis and insertion between flanking MSV or reporter gene sequences contained in Agrobacterium T-DNA derived vectors. Following Agrobacterium-mediated inoculation of maize seedlings, the mutated MSV DNAs were excised from these binary vectors by homologous recombination within the flanking sequences. Our analyses show that the capsid gene of MSV, while not required for replication, is essential for systemic spread and subsequent disease development. The ''+'' strand open reading frame (ORF) located immediately upstream from the capsid ORF and predicted to encode a 10.9 kd protein was also found to be dispensable for replication but essential for systemic spread. By this analysis, MSV sequences that support autonomous replication were localized to a 1.7 kb segment containing the two viral intergenic regions and two overlapping complementary ''-'' strand ORFs. Despite the inability of the gene replacement mutants to spread systemically, both inoculated and newly developed leaves displayed chlorotic patterns similar to the phenotype observed in certain developmental mutants of maize. The similarity of the MSV mutant phenotype to these developmental mutants is discussed.