DETECTION OF Prunus necrotic ringspot virus FROM PEACH (Prunus persica (L.) IN MEXICO AND MOLECULAR CHARACTERIZATION OF ITS COMPONENT RNA-3

Abstract

During field observations from 2008 to 2012 in commercial peach orchards in the Estado de Mexico, states of Morelos and Puebla, leaf damage was observed in the form of yellow mottle, chlorotic rings, linear patterns and mosaic. A virus was transmitted mechanically with affected macerated peach leaves exhibiting yellow mottle to seedlings of several species of tobacco, resulting in whitish spots. In serological diagnoses (DAS-ELISA) and dot-bot type hybridization using riboprobes marked with digoxigenin for detection of six different viruses that infect peach, only the virus Prunus necrotic ringspot virus (PNRSV. Ilarvirus) was detected in the collected samples with symptoms. The electrophoretic analysis of viral ds-RNA obtained from foliage with symptoms showed three bands of 3.6, 2.5 and 1.8 Kbp, molecular weight corresponding to the PNRSV genome. In all of the localities infections by PNRSV were verified in peach plants by direct sequencing of RT-PCR final point products, using extracts of viral ds-RNA as molds and specific oligonucleotides that amplify a 455 pb fragment of the capsid protein gene of this virus. Identity of PNRSV was confirmed by cloning and determining the primary structure of the viral RNA-3 component, which contains the open reading frames corresponding to the movement protein (MP) and the capsid protein (CP). Comparison of nucleotide sequences and the corresponding sequences in amino acids with PNRSV sequences available in the Genbank database, showed 98% and 100%, similarity, respectively. Phylogenetic analyses grouped the three characterized isolates into groups PE5-III and PV32-I. Together, the data presented indicate that the variants of PNRSV in Mexico do not differ from other isolates previously reported, suggesting a probable common origin.