Molecular evidence for the occurrence of two new luteoviruses in cool season food legumes in Northeast Africa

Abstract

Some legume samples with yellowing and stunting symptoms from Ethiopia and Sudan that serologically reacted with a broad-spectrum luteovirus monoclonal antibody did not react or very weakly reacted with virus-specific antibodies suggesting the occurrence of new luteovirus variants. Reverse transcriptase (RT)-PCR amplification, cloning, nucleotide sequencing and analysis of coat protein (CP) gene of a luteovirus isolate from chickpea in Sudan indicated that it shares a closest predicted amino acid sequence identity of only 66% with Soybean dwarf virus (SbDV). Since this is less than the accepted threshold value of 90% recommended for discriminating luteovirus species, the isolate is suggested to represent a distinct luteovirus for which the name Chickpea yellows virus (CpYV) is proposed. Similarly, a lentil isolate from Ethiopia shared a closest CP amino acid sequence identity of 86% with viruses of the Beet western yellows virus subgroup. Following the same criteria, this isolate represents another distinct luteovirus species for which the name Lentil stunt virus (LStV) is suggested. From faba bean, CP sequences of Turnip yellows virus were amplified from Egyptian and Moroccan samples whereas partial CP sequences of SbDV were amplified from Ethiopian, Syrian and Chinese samples. The study indicated that legume luteoviruses in northeast Africa are highly diverse.