Incidence, Distribution and Molecular Characterization of Pea Seed-borne Mosaic Virus (PSbMV) in Egypt

Abstract

Pea seed-borne mosaic virus is an important disease of pea crop and has a wide host range. The field survey was conducted in 2020 and 2021 in different locations of pea-growing fields of four governorates in Egypt to determine the incidence of the virus. Symptoms of virus infection were observed in 25.2 and 28.3 % of total surveyed fields at nine of ten regions in 2020 and 2021, respectively with an incidence ranged between 2 to 28.7%. Naturally infected pea leaves showed symptoms of severe mosaic, downward leaf rolling, vein banding, yellowing, and interveinal chlorosis. The isolated virus was identified based on the symptoms developed on diagnostic hosts, seed transmission, and molecular techniques. The seed transmission tests indicated that seed germination was affected by the virus, as it decreased the germination rate by 56%. The virus was transmitted through seeds where reverse transcription-polymerase chain reaction was used to detect the virus in seedlings produced from infected seeds and the percentage of seed transmission was 18%. 335 bp of the potyvirus coat protein gene and 800 bp of nuclear inclusion protein (NIb) gene of the virus were amplified using a set of degenerate and specific primers, respectively. The two sets of primers succeeded to amplify the partially coat protein gene of a potyvirus and a portion of the NIb gene of the virus. The amplified product was successfully cloned and sequenced. Results of sequence analysis showed similarity ranging between 95-100% compared with twelve reported isolates of the virus. The Egyptian isolate of Pea seed-borne mosaic virus was submitted in the GenBank under the accession number ON075784.