Soybean mosaic virus: A successful potyvirus with a wide distribution but restricted natural host range

Authors: HAJIMORAD, M - University Of Tennessee; Domier, Leslie; TOLIN, S - Virginia Tech; WHITHAM, S - Iowa State University; SAGHAI MAROOF, M - Virginia Tech

Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2017
Publication Date: 2/14/2018
Citation: Hajimorad, M.R., Domier, L.L., Tolin, S.A., Whitham, S.A., Saghai Maroof, M.A. 2018. Soybean mosaic virus: A successful potyvirus with a wide distribution but restricted natural host range. Molecular Plant Pathology. 19:1563-1579.

Interpretive Summary: This manuscript reviews research on Soybean mosaic virus (SMV), a damaging pathogen of soybean that is present in all soybean-growing areas of the world. SMV infections can significantly reduce seed quantity and quality (e.g., mottled seed coats, reduced seed size and viability, and altered chemical composition). Consequently, researchers have intensively investigated structure of SMV particles and their transmission by aphids and through seed. The structure of the SMV genome and its modes of gene expression have been elucidated. The roles of specific virus-encoded proteins in virulence, recognition by soybean resistance genes and the abilities of some SMV isolates to evade soybean resistance responses have been described. Multiple genes for resistance to SMV have been mapped to narrow regions on soybean chromosomes. Genetic pathways that produce resistance responses to SMV have been characterized. Because of this research, the SMV-soybean pathosystem has become an excellent model for examining the genetics and genomics of a host resistance system of unique complexity in a crop of worldwide importance.

Technical Abstract: Soybean mosaic virus (SMV) is a species within the genus Potyvirus, family Potyviridae. The family includes eight genera and almost a quarter of all known plant RNA viruses affecting agriculturally important plants. The Potyvirus genus is the largest with 160 species. The SMV genome consists of a single-stranded positive-sense polyadenylated RNA of approximately 9.6 kb with a virus-encoded protein (VPg) linked at the 5' terminus. The genomic RNA contains a single large open reading frame (ORF). The polypeptide produced from the large ORF is processed proteolytically by three viral-encoded proteinases to yield about 10 functional proteins. A small ORF, pipo, is encoded as a fusion protein with the N-terminus of P3 (P3N+PIPO), partially overlapping the P3 cistron. The natural host range of SMV is restricted mostly to two plant species of a single genus; Glycine max (cultivated soybean) and G. soja (wild soybean). The virus is transmitted non-persistently by aphids and by seeds. Variability of SMV is recognized by reactions on cultivars with dominant resistance (R) genes. Recessive resistance genes are unknown. As a consequence of its seed transmissibility, SMV is present in all soybean growing areas of the world. SMV infection has a potential to reduce significantly seed quantity and quality (e.g., mottled seed coats, reduced seed size and viability, and altered chemical composition). The most effective means to manage losses from SMV are planting virus-free seeds and soybean cultivars containing R resistance (R) genes. The interactions of SMV with soybean genotypes containing different dominant R genes and understanding functional role(s) of SMV-encoded proteins in virulence, transmission and pathogenicity have been intensively investigated. Additionally, the genetics of resistance in soybean to SMV has attracted wide interest. The SMV-soybean pathosystem has become an excellent model for examining the genetics and genomics of a host resistance system of unique complexity in a crop of worldwide importance.