A recently discovered maize polerovirus causes leaf reddening symptoms in several maize genotypes and is transmitted by both the corn leaf aphid (Rhopalosiphum maidis) and the bird cherry-oat aphid (Rhopalosiphum padi)

Authors: Stewart, Lucy; Todd, Jane; Willie, Kristen; MASSAWE, DEOGRACIOUS - The Ohio State University; KHATRI, NITIKA - The Ohio State University

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2019
Publication Date: 4/22/2020
Citation: Stewart, L.R., Todd, J.C., Willie, K.J., Massawe, D., Khatri, N. 2020. A recently discovered maize polerovirus causes leaf reddening symptoms in several maize genotypes and is transmitted by both the corn leaf aphid (Rhopalosiphum maidis) and the bird cherry-oat aphid (Rhopalosiphum padi). Plant Disease. 104(6):1589-1592. https://doi.org/10.1094/pdis-09-19-2054-sc.
DOI: https://doi.org/10.1094/pdis-09-19-2054-sc

Interpretive Summary: Sequences of a new corn virus have been found globally, co-located with an emerging epidemic of maize lethal necrosis, known to be caused by coinfection of two unrelated viruses. However, whether the newly discovered virus causes disease or symptoms in plants was not known. To address this, we separated the new corn virus in corn plants. Without other viruses coinfecting, we demonstrated that the polerovirus itself can cause strong leaf reddening in corn, and can be transmitted to new plants by both the corn leaf aphid and the bird cherry-oat aphid species. These discoveries provide foundational knowledge about the biology included disease symptoms and spread of this virus by insect transmission, and enable detection and management of this virus.

Technical Abstract: A maize-infecting polerovirus species variously named maize dwarf mosaic virus RMV2 (MYDV-RMV2), maize yellow mosaic virus (MaYMV) has been discovered and previously described in East Africa, Asia, and South America. These discoveries were identified in virus surveys in these locations because of outbreaks of maize lethal necrosis (MLN), known to be caused by coinfections of unrelated maize chlorotic mottle virus (MCMV) and any of several maize-infecting potyviruses, and the polerovirus was usually found in coinfections with other viruses including potyviruses and MCMV. Although sequenced in many locations globally and named for symptoms of related or coinfecting viruses, and with an infectious clone reported which experimentally infects Nicotiana benthamiana, even rudimentary biological characterization of MaYMV in maize, including symptoms in single infections and insect vector(s), has not been reported until now. We report isolation from other viruses and leaf tip reddening symptoms in maize, along with transmission by two aphids, Rhopalosiphum padi and Rhopalosiphum maidis. This is important information distinguishing this virus and demonstrating that in single infections it causes symptoms distinct from those of potyviruses or MCMV and provides important vector information to understand transmission and potential management of this polerovirus. This will benefit pathologists and virologists working to manage MLN and co-occuring diseases.