BIOLOGICAL CHARACTERISTICS OF MAIZE-DWARF MOSAIC POTYVIRUS FROM SPAIN

Two isolates of maize dwarf mosaic virus (MDMV-Sp and MDMV-Sp1) obtain ed from maize in the northeast of Spain were studied. Both isolates in duced similar reactions on 6 sorghum cultivars, johnsongrass and oat ( cv. Clintland), with the exception of MDMV-Sp which produced a differe nt reaction on one sorghum cultivar. Thirty three grass species were t ested as possible hosts (16 previously untested) and 18 were found to be susceptible. Among those, eight were previously unidentified hosts for MDMV: Aegilops ovata, A. ventricosa, Avena barbata, Bromus alopecu rus, B. diandrus, B. fasciculatus, Echinaria capitata and Lolium rigid um. Both isolates were transmitted from maize to maize nonpersistently by Rhopalosiphum maidis, R. padi, Schizaphis graminum and Sitobium av enae. The virus was not seed-transmitted in Mo17 and B73 maize inbred lines. Pinwheels, scrolls and short curved laminated aggregates were o bserved in the cytoplasm of maize cells infected by MDMV-Sp or MDMV-Sp 1. In addition, laminated aggregates were observed in cells infected b y MDMV-Sp1.