Evaluation of the resistance of German cultivars of maize and sorghum to Maize streak virus

Maize streak virus (MSV) is the cause of one of the mostdevastating maize diseases in Africa. It is transmitted by leafhoppers of the genus Cicadulina . Due to the changing climate it is possible that species of this genus capable of transmitting MSV will become established and spread the virus in Europe. There is no data on the level of resistance of cultivars of European maize to MSV. The susceptibility of three maize and 15 sorghum cultivars, and Miscanthus × giganteus was investigated using agroinoculation with the virus. DAS-ELISA and a newly developed real time quantitative PCR was used to determine the concentration of virus. All three cultivars of maize were susceptible to MSV administered using agroinoculation, although there were significant differences in the levels of susceptibility. The 15 cultivars of sorghum and Miscanthus were resistant to MSV. Transmission tests using Cicadulina mbila as the vector confirmed the resistance of two of the cultivars of sorghum and Miscanthus . Agroinoculation can only be carried out under S2 biosafety conditions. Therefore, the persistence of agrobacteriain the plants was investigated. Five weeks afteragroinoculation, the bacteria were no longer found in the above-ground parts of the plants, but still persisted in the roots of some plants. Transmission tests with an indigenous species of leafhopper, Psammotettix alienus , a vector of the related geminivirus Wheat dwarf virus , revealed that this species is not capable of transmitting MSV. Virus was found only in the body of these insects and not in their heads, which is necessary for persistent transmission through salivary glands.