Partial genome sequence of a Potyvirus and of a virus in the order Tymovirales found in Senna macranthera in Brazil

Abstract

Senna macranthera is a common tropical tree native to South- and Northeastern Brazil. In July 2006, symptoms of chlorotic spots in the young leaves and mild mosaic in the old leaves were observed in S. macranthera trees at Viçosa, State of Minas Gerais, Brazil. Electron microscopy examination of leaf dip preparations from the young leaves revealed the presence of flexuous rods. Viral RNA was extracted from purified virion preparations and used as a template for the RT-PCR-based cloning of viral genomic fragments. Two fragments (0.9 kb and 2.0 kb in length) were cloned. Sequence analysis of the 0.9 kb fragment indicated that it corresponded to the NIb coding region of a potyvirus, with nucleotide (nt) identity level of 72% for Pepper mottle virus (PepMoV) and Peru tomato mosaic virus (PTV), while analysis of the 2.0 kb fragment indicated that it corresponded to the putative replicase ORF, which displayed 74% nt identity with the ORF1 (replicase) of Garlic virus A (GarV-A). Based on molecular analysis and the isolates' host range, it is concluded that the viral fragments represent new viruses, for which we propose the names Senna virus Y (genus Potyvirus, family Potyviridae) and Senna virus X (unassigned genus, order Tymovirales).