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TECHNICAL SESSION: Virus discovery and virus populations

The use of highthroughput sequencing for detection and characterization of diverse viruses infecting common beans (Phaseolus vulgaris L.) in Zambia
Rabson Mulenga - Zambia Agriculture Research Institute. Evans Kaimoyo- University of Arizona, Felister Nzuve- University of Nairobi, Maher Al Rwahnih- University of California-Davis, Douglas Miano- University of Nairobi, Olufemi Alabi- Texas AgriLife Research and Extension Center

Common bean (Phaseolus vulgaris L.) is an important legume crop in Zambia. However, very little is known about the etiological agents of highly prevalent yield-limiting viral diseases across bean fields in Zambia. Field surveys were conducted during 2017/2018 rainy season across 128 fields, and 641 leaf tissue samples showing virus-like symptoms such as mosaic, necrosis, vein-clearing, curling and rugosis were systematically sampled. Total nucleic acid extracts from these samples were pooled into one composite sample which was first ribo-depleted, then used for cDNA library construction. The library was sequenced using the Illumina NextSeq 500 platform. A tBLASTX analysis of the de novo assembled virus-specific highthroughput sequence contigs (ranging in length from 206 to 5207 nt) resulted in the identification of partial and near complete genome sequences of six viruses belonging to three genera in the sample. They include two known potyviruses, two known alphaendornaviruses, a putative novel Orthotospovirus, and a putative novel Begomovirus. The results represent the first report and molecular characterization of most of these viruses in Zambia. Studies are ongoing to determine the complete genomes of these viruses, their biological properties and prevalence across common bean fields in Zambia.