Analysis of molecular interactions between a novel bromovirus and Arabidopsis thaliana

溴花叶病毒（BMV）是研究最多的植物病毒之一，但不感染模式植物，如拟南芥。我们最近发现了一种相关的溴病毒，春美人病毒（SBLV）系统有效地感染拟南芥。为了建立SBLV与拟南芥分子相互作用的分析体系，我们首先构建了SBLV基因组rna的生物活性cDNA克隆，并确定了它们的完整核苷酸序列。为了确定与SBLV侵染有关的植物因子，(1)用EMS诱变2231株M2 （col0背景）植株，鉴定出1个SBLV侵染延迟的突变株系，该突变株系的SBLV侵染在细胞间运动阶段受到影响，遗传分析表明SBLV在该株系中传播较慢是隐性的。(2)对67个拟南芥植株进行SBLV接种，发现其中一个植株Pla-O至少延缓了SBLV在接种叶片中的传播。在Pla-0中的SBLV感染被证明是在细胞间移动的步骤中受到影响，而不是在单个细胞内增殖。遗传分析表明，SBLV在Pla-0中的传播速度较慢是隐性或半显性性状。(3)观察了拟南芥感染SBLV后的症状发展情况。在85份拟南芥材料中，包括S96在内的4份材料对SBLV感染敏感，而包括Col-0在内的其他材料无症状或仅出现轻度症状。遗传研究表明，S96的症状表型由单个半显性基因控制。我们把这个地点指定为SSBI。SBLV在植物和原生质体中的传染性在col0和S96之间具有可比性，表明症状表型的变化不是由SBLV的不同传染性引起的。利用遗传标记，在四号染色体上的ATMB3R和JM142之间定位了SBLV的SSBI。

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.