Survey for the identification and geographical distribution of viruses and virus diseases of maize (Zea mays L.) in Ethiopia

Abstract

A survey to identify the distribution of virus diseases of maize was made in major maize growing regions of Ethiopia. Four surveys were conducted between 2015 and 2017. A total of 284 maize fields have been surveyed, of which 846 leaf samples with virus like disease symptoms were collected from 191 fields. There were no symptoms indicating for virus presence in maize grown in 93 fields which were exempted from sampling, while in contrast up to 100% disease incidence was recorded in maize grown in the Benishangul-Gumuz, Oromia and South Nations, Nationalities and People (SNNP) regions. Symptoms varied in maize ranging from the most common mosaic and streak to severe leaf mottling and necrosis as well as stunting and pre-mature plant death. Double or triple antibody sandwich (DAS or TAS) enzyme-linked immuno-sorbent assay (ELISA) to test for eight common maize viruses such as Maize chlorotic mottle virus (MCMV), Sugarcane mosaic virus (SCMV), Maize streak virus (MSV), Maize dwarf mosaic virus (MDMV), Maize mosaic virus (MMV), Maize stripe virus (MSpV), Wheat streak mosaic virus (WSMV) and Johnsongrass mosaic virus (JGMV) confirmed the presence of MCMV, SCMV and MSV in the leaf samples. Single or mixed infections with MCMV and SCMV frequently occurred and triple infections of MCMV, SCMV and MSV were found in 1% of samples from SNNP region. Sequence analysis of the coat protein genes of randomly selected seropositive samples of the three viruses showed little variability within the studied isolates and those retrieved from the GenBank. Our results indicated maize lethal necrosis disease (MLND) caused by MCMV and SCMV co-infection was the most important disease in SNNP and Oromia while maize streak disease was the predominant virus infecting maize in Benishangul-Gumuz.