Pathological and genome assembly of transcriptome sequencing data implied multiple relationships between bean common mosaic virus (BCMV), Batocera lineolata and aphids in Populus alba var. pyramidalis

This paper reports a novel poplar mosaic disease that occurred on the leaves of Populus alba var. pyramidalis in China. Symptoms: mosaic and chlorosis leaves, leaf abscission, leaf and young branch withering, leaf growth retard, and the destroyed and hollowed cell structures of mesophyll cells in the diseased leaves. Electron microscopy observation showed that some typical (flexible rods, virus particles 10-14 nm in width, and ca. 700 nm in length) and atypical virus particles (1400 or 2000 nm in length) of genus Potyvirus were found in the leaf exudates of the diseased poplar. De novo assembly assembled a nearly complete genome sequence of bean common mosaic virus (BCMV, 10035 nt in length) from the transcriptome sequencing data of poplar leaves. Moreover, field observation illustrated that two larvae of white-striped longhorn beetle (Batocera lineolata) inhabited and almost completely destroyed the main branch and roots of the diseased poplar plant, and a high-density population of two Chaitophorus aphid species once infected poplar plants before the occurrence of mosaic symptoms. Results suggested that BCMV is the pathogen of this novel poplar mosaic disease; moreover, results also suggested beetle and aphids that might involve in the occurrence and development of poplar mosaic disease.