The westward journey of alfalfa leaf curl virus

Alfalfa leaf curl virus (ALCV), which causes severe disease symptoms in alfalfa (Medicago sativa L.) and is transmitted by the widespread aphid species, Aphis craccivora Koch, has been found throughout the Mediterranean basin as well as in Iran and Argentina. Here we reconstruct the evolutionary history of ALCV and attempt to determine whether the recent discovery and widespread detection of ALCV is attributable either to past diagnostic biases or to the emergence and global spread of the virus over the past few years. One hundred and twenty ALCV complete genome sequences recovered from ten countries were analyzed and four ALCV genotypes (ALCV-A, ALCV-B, ALCV-C, and ALCV-D) were clearly distinguished. We further confirm that ALCV isolates are highly recombinogenic and that recombination has been a major determinant in the origins of the various genotypes. Collectively, the sequence data support the hypothesis that, of all the analyzed locations, ALCV likely emerged and diversified in the Middle East before spreading to the western Mediterranean basin and Argentina

First Report of Cucurbit aphid-borne yellows virus Affecting Chickpea (Cicer arietinum L.) in Sudan

A total of 204 chickpea samples with symptoms typical of virus infection including stunting, yellowing, necrosis, reddening, and tip wilting were collected during February 2013 and March 2015 from 14 chickpea fields located in Gizera, middle Gizera, Barbar, Shendi and Hudiba, Sudan. All samples were tested using tissue-blot immunoassay (TBIA) (Makkouk and Kumari, 1996) against a battery of legume virus antibodies including a broad-spectrum legume luteovirus monoclonal antibody (McAb) (5G4; Katul, 1992). To identify the luteoviruses affecting chickpea in Sudan, 41 chickpea samples that gave positive reaction to 5G4 McAb were tested using generic reverse transcription polymerase chain reaction (RT-PCR) Luteovirus primer pairs (Asaad et al. 2009; Abraham et al. 2009). Direct sequencing of these products indicated that 12 samples were related to Cucurbit aphid-borne yellows virus (CABYV). To confirm this data, all samples were tested again by RT-PCR using CABYV-specific primer CABYV3635F (5’-GAAACCGCCGACGCCCTAAT-3’; this study) and primer AS3 (Abraham et al. 2009). Results showed that 12 of the 41 samples that gave positive reactions to 5G4 McAb generated RT-PCR amplicons of the partial coat protein gene of the expected size (481 bp) and were considered positive for CABYV. Amplicons from two chickpea samples (isolates SuCp106-13 and SuCp122-13) were directly sequenced in both directions. After removal of primers, the resulting sequences were 435 nucleotides in length (GenBank accessions numbers MG933685 and MG933686). The two isolates shared 100% nt identity with each other and 96% nt identity with the type reference sequence for CABYV, NC_003688. Moreover, we confirmed the presence of CABYV in RT-PCR positive samples serologically with TBIA using polyclonal antisera (provided by Lecoq, INRA, France). The observed symptoms in CABYV-infected chickpea plants were stunting, accompanied by leaf yellowing and necrosis and is likely to reduce yield similar to other Luteoviruses. Of the 204 virus-symptomatic plants we tested in this study, 12 were positive for CABYV (6% of the samples tested). Chickpea is an economically important crop in many countries of the world and knowing the exact identity of a virus affecting this crop in a region is essential for breeding for resistance and crop management purposes. CABYV and its aphid vector (Aphis gossypii Glover) were reported on cucurbit crops in many countries of the world with high yield loss. Further disease surveillance will be needed to determine if CABYV continues to impact chickpea production in Sudan and if it is also present in other chickpea production regions of the world. CABYV was reported recently on broad bean (Vicia faba L.) in Turkey (Buzkan et al. 2017), but based on our knowledge this is the first report of CABYV on chickpea in Sudan and worldwide

Molecular diagnosis of viruses causing yellowing and stunting symptoms affecting pulse crops in Central West Asia and North Africa Countries

Viruses causing yellowing and stunting are the most important virus diseases affecting pulses in many regions of the world, and were considered for many years to be caused mainly by infection with beet western yellows virus (BWYV, genus Polerovirus, family Luteoviridae). Knowing the exact identity of a virus affecting pulse crops is essential for breeding for resistance and crop management purposes. More than 5000 pulse samples (faba bean, lentil, and chickpea) with symptoms typical of virus infection including stunting, yellowing, necrosis and reddening were collected during the last two decades from different countries in Central West Asia and North Africa (CWANA). All samples were tested serologically by tissue-blot immunoassay (TBIA) technique using specific luteoviridae monoclonal antibodies. Selected samples were further tested by reverse transcription polymerase chain reaction (RT-PCR) using different luteoviridae primer pairs (generic and specific) followed by amplicon sequencing. RT-PCR results revealed clearly that there was a greater variation in polerovirus species detected than was indicated by TBIA alone. Molecular diagnosis has clearly shown that there are a number of Polerovirus species, in addition to BWYV (detected in Algeria, Ethiopia, Lebanon, Morocco, Sudan, Tunisia and Uzbekistan), each of which can produce yellowing and stunting symptoms in pulses in CWANA. These viruses are cucurbit aphid-borne yellows virus (detected in Algeria, Lebanon, Syria, Sudan and Uzbekistan), chickpea chlorotic stunt virus (detected in Algeria, Ethiopia, Lebanon, Morocco, Syria, and Tunisia), pepper vein yellows virus (detected in Morocco and Sudan), pepo aphid-borne yellows virus (detected in Sudan), and cotton leafroll dwarf virus (detected in Sudan and Uzbekistan). This study clearly showed that molecular characterization is an essential tool for accurate identification of plant viruses, which is the first step towards better crop managemen