Experimental host range and pathogenicity on maize of maize striate mosaic virus transmitted by the corn leafhopper

Maize striate mosaic virus (MSMV, species Mastrevirus striatis) is an emergent mastrevirus (Geminiviridae) in South America, transmitted by the corn leafhopper Dalbulus maidis. MSMV symptoms in maize (Zea mays) include mottling with mild chlorotic streaks, but the extent of its damage and host range remain unstudied. In greenhouse experiments, we assessed 17 plant species (including maize as a control) as hosts to MSMV by symptomatology and PCR detection in 9-30 test plants per species, which were inoculated by caging 20 viruliferous leafhoppers/plant during 48 h; 3-5 plants/species were exposed to aviruliferous leafhoppers (negative controls). MSMV was detected in four inoculated grass species, Urochloa brizantha, Andropogon gayanus, Saccharum spp. and Pennisetum glaucum, but only Saccharum spp. (cv. CTC-9005) showed symptoms (chlorotic stripes). In maize, the virus was detected in 51.8% of the inoculated plants, of which only 45.9% showed typical MSMV symptoms (mottling and/or chlorotic streaks). We also evaluated the MSMV pathogenicity in two maize hybrids after inoculation with viruliferous leafhoppers caged at a density of 20 individuals/plant for 72 h; the inoculated hybrid plants and respective controls (exposed or not to aviruliferous leafhoppers) were grown in pots in a greenhouse to assess symptoms and yield. A multivariate analysis showed that the MSMV impact on maize varied with infection type (symptomatic vs. asymptomatic). Both hybrids were highly affected when symptoms developed, whereas asymptomatic infection did not significantly alter plant development but still reduced grain yield in one hybrid. These findings are essential for understanding the virus impact, transmission ecology and management strategies.