Detection of Maize rough dwarf virus in Spain: a survey of susceptible host genotypes and molecular characterization of two genomic segments of the virus

Abstract

An increase in the number of plants infected with Maize rough dwarf disease (MRDD) has been reported recently in Spain. The disease was presumed to be caused by Maize rough dwarf virus (MRDV), but there was no conclusive evidence for this assumption. Two viruses have been associated with MRDD: Rice black streaked dwarf virus (RBSDV) and MRDV. In this study, maize plants showing MRDD in the Ebro zone province of Lerida, Spain were assessed using common primers for MRDV and RBSDV. Molecular characterization of one isolate and phylogenetic analysis were also carried out. Polyacrylamide electrophoretic profiles of genome segments of dsRNA, the size of PCR amplified fragments and the nucleotide sequence comparison matched closely with Maize rough dwarf virus Italian isolate (MRDV accession no. L76561), confirming that MRDV is present in maize plants showing MRDD in Spain. The phylogenetic analysis made with segments S9 and S10 from Fijivirus and the MRDV-Sp isolate obtained in the present study, showed that: i) MRDV is closely related to RBSDV; ii) there is high variability within isolates clustering as RBSDV in S9, especially in the ORF1 at the amino acid level, which allowed grouping one isolate close to MRDV; and iii) the grouping of RBSDV isolates at the 3’NCR of S9 was correlated with the host. The incidence of MRDD varied between two locations sampled, probably associated with sowing date, the presence of the winged form of the MRDV vector Laodelphax striatellus and differences in the abundance of virus reservoir plants.

Keywords

• Fijivirus
• etiology
• resistance maize