Identification of new tetrad variants of beet necrotic yellow vein virus (Benyvirus necrobetae) in Iran

Document Type : Research Article

Authors

1 Assistant Professor, Sugar Beet Research Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran.

2 Associate Professor, Department of Plant Pathology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

Abstract

Rhizomania is a destructive viral disease in sugar beet. It is caused by the beet necrotic yellow vein virus (BNYVV; Benyvirus necrobetae), and, a Benyvirus transmitted by the soil inhabiting plasmodiophorid Polymyxa betae. Despite identification of resistance genes, BNYVV remains a major constraint because of resistance-breaking events as well as its ability to survive for long periods in soils in resting spores of P. betae. In this study, severe symptoms of rhizomania disease were observed in resistant sugar beet genotypes carrying the Rz1 gene in the fields, which indicated the resistance-breaking events. Plants from severely infected fields were sampled and total RNA was extracted from root hairs. BNYVV was detected using reverse transcription polymerase chain reaction (RT-PCR). The virus isolates were tested for the presence of RNA5 and RNA3 using RT-PCR targeting P26 and P25 genes, respectively. The results showed that all the tested BNYVV isolates were type A However, types B and P were not detected. Next, the P25 protein coding gene of the RNA3 strand of these isolates was sequenced and nucleotide synonyms were determined. Determining the sequence of 650 base pairs of P25 protein, eight types of tetrad variants were identified in the so-called tetrad region (aa67-70). These tetrad variants included ACHG, AHHG, TLHG, VHHG, VCHG, AYHG, ALHG and ARHG, of which three variants TLHG, ARHG and VCHG are reported for the first time from the sugar beet fields of Khorasan province and Iran.

Keywords

Iranian Journal of Plant Pathology
Volume 60, Issue 4
December 2025
Pages 379-400

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