Abstract
In a survey conducted in 2012 and 2013, 1166 samples from alfalfa plants and 202 samples from symptomatic weeds and cultivated plants growing adjacent to alfalfa fields were collected. Using DAS-ELISA, Alfalfa mosaic virus (AMV) was detected in 58.4% of the alfalfa samples and in 63.9% of the weeds and cultivated plants samples. ELISA detection of AMV was confirmed by testing representative samples from all regions by RT-PCR using a pair of primers (AMV/F and AMV/R) specific to the AMV coat protein (CP) gene. The size of the major product obtained from AMV-infected plants was identical to the 700 bp size expected from the CP gene of AMV. The amino acids and the nucleotide sequences of 17 Saudi AMV isolates from alfalfa, and 16 from other cultivated plants and weeds detected in different regions in Saudi Arabia showed a percentage of similarity that ranged between 87.9%-100% among them and 86.2% - 100% when compared with sequences of 15 different AMV isolates reported in the GenBank. This is the first time AMV was detected in Vigna unguiculata and in the following weed plant species: Chenopodium quinoa, Convolvulus arvensis, Malva parviflora, Hibiscus spp., Hippuris vulgaris, Cichorium intybus, and Flaveria trinervia in Saudi Arabia.