Full Length Research Paper

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

A. D. Abraham ^1,2,3*, M. Varrelmann² and H. J. Vetten¹

¹Federal Biological Research Center for Agriculture and Forestry (BBA), Institute of Plant Virology, Microbiology and Biosafety, Messeweg 11-12, 38104 Braunschweig, Germany.
²University of Göttingen, Institute of Plant Pathology and Plant Protection, Grisebachstr. 6, 37077 Göttingen, Germany.
³Ethiopian Institute of Agricultural Research, National Plant Protection Research Centre, P.O. Box 37, Ambo, Ethiopia.

*Corresponding author. E-mail: adaneabraham@yahoo.com. Tel: 251 112362036 or 251 911896135. Fax: 0112362325.

Accepted 4 January, 2008

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.

Key words: Phylogenetic relationship, sequence alignment, Polerovirus, Luteoviridae.