Genetic Diversity and Potential Vectors and Reservoirs of Cucurbit aphid-borne yellows virus in Southeastern Spain

Abstract

The genetic variability of a Cucurbit aphid-borne yellows virus (CABYV) (genus Polerovirus, family Luteoviridae) population was evaluated by determining the nucleotide sequences of two genomic regions of CABYV isolates collected in open-field melon and squash crops during three consecutive years in Murcia (southeastern Spain). A phylogenetic analysis showed the existence of two major clades. The sequences did not cluster according to host, year, or locality of collection, and nucleotide similarities among isolates were 97 to 100 and 94 to 97% within and between clades, respectively. The ratio of nonsynonymous to synonymous nucleotide substitutions reflected that all open reading frames have been under purifying selection. Estimates of the population's genetic diversity were of the same magnitude as those previously reported for other plant virus populations sampled at larger spatial and temporal scales, suggesting either the presence of CABYV in the surveyed area long before it was first described, multiple introductions, or a particularly rapid diversification. We also determined the full-length sequences of three isolates, identifying the occurrence and location of recombination events along the CABYV genome. Furthermore, our field surveys indicated that Aphis gossypii was the major vector species of CABYV and the most abundant aphid species colonizing melon fields in the Murcia (Spain) region. Our surveys also suggested the importance of the weed species Ecballium elaterium as an alternative host and potential virus reservoir.

Presence of Recombinant Strain of Cucurbit Aphid Borne Yellows Virus in Iran

“…Our results also showed the infection of S. irio and C. colocynthis as the reservoir hosts for CABYV in planting area of this country, as well. Although Kassem et al (11) have suggested the CABYV infection for Senecio vulgaris and Lamium amplexicaule, no infection was found among the collected samples from these species in this investigation. Our data suggest that weeds could be a critical factor in the maintenance and dissemination of the CABYV infections in cucurbit crops.…”

“…CABYV is one of the most important yellowing viral diseases of the cucurbit crops (11,20) as it can cause yield losses up to 40-50% in the cucumber and melon, if the infection occurs at an early stage (7). In Iran, also CABYV is one of the most prevalent viruses in the major cucurbit crops and has been detected in the main cucurbit producing provinces; both in the greenhouses as well as open fi eld plantation areas (15).…”

“…As well, the mechanical transmission has never been reported for this viral infection (7). CABYV infects more crop plants other than cucurbits, like Lactuca sativa and Beta vulgaris, as well as common weeds of the species Capsella bursa-pastoris, Crambre abyssinica, Bryonia dioica, Ecballium elaterium, Lamium amplexicaule, Montia perfoliata, Papaver rhoeas, and Senecio vulgaris which seems to serve as the virus reservoirs (7,11,12).…”

“…The CABYV population has been previously classifi ed into two strains named as common (CABYV-C) and recombinant (CABYV-R) by using a set of universal polerovirus primers (14). The recombinant CABYV-R strain most likely has emerged through recombination in the intergenic rejoin (IR), a recombination hot-spot of the poleroviruses, between ancestors of Melon aphid-borne yellows virus (MABYV) and CABYV-C strain (11,14).…”

Whitefly‐transmitted RNA viruses that affect intensive vegetable production

“…This changing environment may favour the emergence of new viruses and vectors (Navas‐Castillo et al , ). For instance, during the last 15 years, production of cucurbits in Western Mediterranean countries has been seriously compromised by a series of successive epidemics caused by Cucurbit yellow stunting disorder virus (CYSDV; Célix et al , ), Cucumber vein yellowing virus (CVYV; Cuadrado et al , ) and Cucurbit aphid‐borne yellows virus (Kassem et al , ).…”