Turnip mosaic virus (TuMV) infects many plant species, being the only potyvirus able to infect brassicas. TuMV isolates have been classified into 12 pathotypes according to symptoms induced in lines of Brassica napus, and molecularly clustered into six lineages (basal-B, basal-BR, Asian-BR, world-B, Iranian and OMs). Despite being considered one of the most important viruses infecting brassicas worldwide, there is little information on this virus in the Neotropical region. Aiming to fill in this gap and advance knowledge on occurrence, genetic variability, and biological aspects of TuMV in Brazil, 40 isolates were identified and characterised. Five of these isolates were selected to determine their host range, sequence their genomes, and for phylogenetic, recombination and diversity analyses. Mechanical inoculations performed on plant species from 10 families showed differences in symptom expression among isolates. Inoculations of 13 TuMV isolates in B. napus lines revealed occurrence only of the pathotype 1. According to phylogenetic analyses of the coat protein, TuMV Brazilian isolates clustered into the groups: world-B (subgroups world-B2 and world-B3) and basal-BR. In the latter, there was a formation of a subclade named Brazilian subgroup composed by 31 Brazilian TuMV isolates. Intralineage and interlineage recombination events of world-B, basal-B and basal-BR suggest that Brazilian TuMV isolates had a European origin. Our diversity analysis suggest that a strong negative selection is acting on polyprotein coding region. We confirmed that Brazilian TuMV isolates showed high variability, which together with their ability to infect wild brassicas and to circumvent resistance genes highlight their genetic and epidemiological potential in causing damages in cultivated species of brassicas and other crops in Brazil.

芜菁花叶病毒 (TuMV) 感染许多植物物种，是唯一能够感染芸苔属植物的病毒。根据甘蓝型油菜品系诱导的症状，TuMV 分离株已分为 12 种致病型，并在分子上聚集成六个谱系（basal-B、basal-BR、Asian-BR、world-B、Iranian 和 OMs）。尽管被认为是世界范围内感染芸苔属植物的最重要病毒之一，但在新热带地区几乎没有关于这种病毒的信息。为了填补这一空白并提高对巴西 TuMV 发生、遗传变异和生物学方面的认识，鉴定并表征了 40 个分离株。选择了其中的五个分离株来确定它们的宿主范围，对它们的基因组进行测序，并进行系统发育、重组和多样性分析。对来自 10 个科的植物物种进行机械接种显示分离株之间的症状表达存在差异。在欧洲油菜中接种 13 个 TuMV 分离株线显示仅发生了致病型 1。根据外壳蛋白的系统发育分析，TuMV 巴西分离株聚集成以下组：世界 B（世界 B2 和世界 B3 亚组）和基础 BR。在后者中，形成了一个名为巴西的分支由 31 个巴西 TuMV 分离株组成的亚组。World-B、basal-B 和 basal-BR 的系内和系间重组事件表明巴西 TuMV 分离株起源于欧洲。我们的多样性分析表明，强大的负选择作用于多蛋白编码区。我们证实，巴西 TuMV 分离株表现出高度的变异性，连同它们感染野生芸苔属植物和规避抗性基因的能力，突出了它们在巴西栽培芸苔属植物和其他作物物种中造成损害的遗传和流行病学潜力。