Analysis of molecular interactions between a novel bromovirus and Arabidopsis thaliana

雀麦花叶病毒（BMV）是研究最多的植物病毒之一，但不侵染模式植物如拟南芥。我们最近发现，一个相关的溴病毒，春美人latnet病毒（SBLV）系统和有效地感染A。thaliana.建立SBLV与A. thaliana中，我们首先构建了具有生物活性的SBLV基因组RNA的cDNA克隆，并测定了它们的完整核苷酸序列。为了鉴定与SBLV侵染有关的植物因子，（1）用EMS诱变的2,231株M_2（Col-0背景）植株接种，鉴定出一个SBLV侵染延迟的突变系，该突变系的SBLV侵染受细胞间运动的影响。遗传分析表明，SBLV在该突变系中传播较慢是隐性的。(2)我们用SBLV接种67个拟南芥品种，发现一个品种Pla-O的SBLV传播至少在接种叶片中延迟。SBLV在Pla-0中的感染是在细胞间的传播阶段而不是在单个细胞内的复制阶段，遗传分析表明，SBLV在Pla-0中传播较慢是隐性或半显性性状。(3)在A.感染SBLV的thaliana加重。在85份供试的拟南芥材料中，包括S96在内的4份材料对SBLV的侵染表现出敏感性，而包括Col-0在内的其他材料则表现为不感病或仅表现出轻微的症状。遗传学研究表明，S96的症状表型受一个半显性基因控制。我们已经指定这个位点为SSBI。Col-0和S96的侵染力在植株和原生质体中基本一致，表明症状表型的差异不是由于SBLV侵染力的不同所致。利用遗传标记将SSBI定位在第IV染色体上的ATMB 3R和JM 142之间。

Brome mosaic virus (BMV) is one of the most-studied plant virues, but does not infect model plants such as Arabidopsis thaliana. We have recently found that a related bromovirus, Spring beauty latnet virus (SBLV) systemically and efficiently infects A. thaliana. To establish a system for the anlysis of molecular interactions between SBLV and A. thaliana, we first constructed biologically active cDNA clones of SBLV genomic RNAs and determined their complete nucleotide sequences. To identify plant factor(s) involved in SBLV infection, (1) We inoculated 2,231 M2 (Col-0 background) plants mutagenized with EMS treament and identified one mutart line in which SBLV infection was delayed The SBLV infection in this line was shownto be affected at the step of the cell-to-cell movement Genetic analysis demonstrated that slower SBLVspread in this line was recessive. (2) We inoculated 67 Arabidopsis accesions with SBLV, and found anaccession, Pla-O in which SBLV spread was delayed at least in incculated leaves. The SBLV infection in Pla-0 was shown to be affected At the step of the cell-to-cell raovement rather than maltiplication within a single (cell.Genetic analysis demonstrated that slower SBLV spread in Pla-0 was recessive or semidominant trait. (3) Symptom development was examined in A. thaliana accenssions infected with SBLV. Of 85 Arabidopsis accessions tested, four accessions including an accession S96 were Scnsitive to SBLV infection, while the otner accessions including Col-0 were symptomless or developed only mild symptoms. Genetic study suggested that the symptom phenotype of S96 is controlled by a single semidominant lolcus. We bave designated this locus SSBI. Infectivity of SBLV in plants and protoplasts were compalable between Col-0and S96, indicating that variation of symptom phenotype was not due to the different infectivity of SBLV By using genetic markers, SSBI was mapped between ATMB3R and JM142 on chromosome IV.