双生病毒是一类在世界范围内广泛发生的植物单链DNA病毒，每年在全世界农作物上引起严重的病害，造成重大经济损失。卫星DNAβ是一类伴随单组份双生病毒并诱导病毒病害成灾的单链环状DNA分子。至今报道DNAβ只在互补链上编码唯一的蛋白βC1，它是一个致病因子和RNA沉默抑制子。在前期研究中，我们发现约40%的DNAβ分子在病毒链上具有一段编码序列，位置和大小都较为保守，我们将其命名为βV1。在伴随有DNAβ的双生病毒侵染的植物中，我们检测到病毒βV1转录本的存在并确定了其转录起始位点。本项目将分析βV1蛋白对病毒侵染的影响、βV1基因在病毒复制、运动及症状诱导中的功能、明确其抑制转录水平和转录后基因沉默的作用机制，最终揭示βV1的重要生物学功能及其在病毒侵染中发挥作用的分子机制。研究结果将为防控双生病毒提供新的理论依据。

Geminiviruses are a group of DNA viruses that infect important crops to cause serious damages in agriculture and lead to a great economic loss worldwide. Betasatellites (DNA β) are a class of single-stranded circular DNA molecules that are associated with monopartite geminiviruses to induce devastating diseases. So far, it has been recognized that DNA β encodes a unique viral protein βC1 on the complementary strand, which is a pathogenic factor and RNA silencing suppressor. Our preliminary data showed an open reading frame named βV1 exists in the viral strand of DNA β, which is conserved in position and size among approximately known 40% of DNA β, We detected the presence of the βV1 transcript and identified its transcriptional initiation site in plants infected by the geminivirus and DNA β complex. This project will analyze the role of βV1 gene in virus infection. Functions of βV1 gene in virus replication, movement, symptom induction, repressing transcriptional level and post-transcriptional level-induced gene silencing will also be carried out. This work will reveal biological functions of βV1 and its molecular role in viral infection, which would provide a new theoretical basis for the effective control of geminiviruses in the future.