Forage crops occupy large areas of tropical pastures for cattle feeding in Brazil. The use of stylos (Stylosanthes spp.) in these pastures, which are leguminous shrubs, has increased in the country due to their outstanding nutritional value and for being an efficient and alternative source for nitrogen fixation in the soil. In recent years, virus-like mosaic symptoms on S.guianensis leaves have often been observed in the field, indicating possible virus-like pathogen infections. In an effort to identify the causal agent, virus semi-purification protocol was performed using symptomatic S. guianensis leaves collected at EMBRAPA Beef Cattle Research Center. Total RNA extracted from this semi-purified preparation was submitted to high-throughput sequencing, which revealed complete genome sequences of novel viruses of the family Potyviridae. These viruses, tentatively named stylo mosaic-associated virus 1 (StyMaV-1) and stylo mosaic-associated virus 2 (StyMaV-2), shared 73 % CP aa identity and 77 % polyprotein aa identity with each other and, after that, being closest related to blackberry virus Y, genus Brambyvirus (only 41 % CP aa identity). Based on ICTV genus demarcation criteria, StyMaV-1 and StyMaV-2 represent new species of a new genus within the family Potyviridae. StyMaV-1 and StyMaV-2 are also not efficiently transmitted to other plant species by mechanical inoculation.

在巴西，饲料作物占据了大片热带牧场供牛饲养。由于其出色的营养价值和作为土壤固氮的有效替代来源，在这些属于豆科灌木的牧场中使用柱花柱（Stylosanthes spp.）有所增加。近年来，在田间经常观察到贵阳叶上的病毒样花叶症状，表明可能存在病毒样病原体感染。为了确定致病因子，使用有症状的S. guianensis进行病毒半纯化方案在 EMBRAPA 肉牛研究中心收集的叶子。从这种半纯化制剂中提取的总 RNA 进行了高通量测序，揭示了Potyviridae家族新型病毒的完整基因组序列。这些病毒，暂定名为花柱花叶相关病毒 1 (StyMaV-1) 和花柱花叶相关病毒 2 (StyMaV-2)，彼此具有 73% 的 CP aa 同一性和 77% 的多蛋白 aa 同一性，之后分别为与黑莓病毒 Y、Brambyvirus属最接近（仅 41% CP aa 同一性）。根据ICTV属划分标准，StyMaV-1和StyMaV-2代表Potyviridae科内一个新属的新种. StyMaV-1 和 StyMaV-2 也不能通过机械接种有效地传播给其他植物物种。