Epidemiology of Yam Viruses in Guadeloupe: Role of Cropping Practices and Seed-Tuber Supply

Abstract

The epidemiology of yam viruses remains largely unexplored. We present a large-scale epidemiological study of yam viruses in Guadeloupe based on the analysis of 1124 leaf samples collected from yams and weeds. We addressed the prevalence of cucumber mosaic virus (CMV), Cordyline virus 1 (CoV1), Dioscorea mosaic associated virus (DMaV), yam asymptomatic virus 1 (YaV1), yam mosaic virus (YMV), yam mild mosaic virus (YMMV), badnaviruses, macluraviruses and potexviruses, and the key epidemiological drivers of these viruses. We provide evidence that several weeds are reservoirs of YMMV and that YMMV isolates infecting weeds cluster together with those infecting yams, pointing to the role of weeds in the epidemiology of YMMV. We report the occurrence of yam chlorotic necrosis virus (YCNV) in Guadeloupe, the introduction of YMMV isolates through the importation of yam tubers, and the absence of vertical transmission of YaV1. We identified specific effects on some cropping practices, such as weed management and the use of chemical pesticides, on the occurrence of a few viruses, but no crop-related factor had a strong or general effect on the overall epidemiology of the targeted viruses. Overall, our work provides insights into the epidemiology of yam viruses that will help design more efficient control strategies.

Identification of yam mosaic virus as the main cause of yam mosaic diseases in Ethiopia

“…Yam production is adversely affected by several constraints including biotic stresses such as pests and diseases, mainly viruses, bacteria and fungi, as well as abiotic stresses like decline in soil fertility [ [7] , [8] , [9] ]. Different species of viruses belonging to the genera Aureusvirus, Badnavirus, Cucumovirus, Macluravirus, Potyvirus, Potexvirus and Tobamovirus have been reported threatening yams production worldwide [ [10] , [11] , [12] , [13] , [14] ].…”

Molecular diversity of yam virus Y and identification of banana mild mosaic virus isolates infecting yam (Dioscorea spp.)

“…In order to fill these knowledge gaps, we undertook a comprehensive prevalence survey of yam-infecting Betaflexiviridae members using three sampling sources (Supplementary Table S1). The first source, referred to as ‘Guadeloupe’, included 896 leaf samples of the species D. alata , D. bulbifera , D. cayenensis , D. esculenta , D. rotundata , and D. trifida collected between November 2019 and December 2020 from 18 yam fields scattered across Guadeloupe, as described by Diouf et al [ 8 ]. Considering that the relationship between leaf symptoms and viral infection in yam is poorly documented, symptoms, or lack thereof, were not taken into consideration during sample collection.…”

“…Whether such transmission occurs mechanically through the use of infected tools for fragmenting yam tubers before planting or involves biological vectors remains to be elucidated. YVY might also be transmitted vertically through vegetative propagation and the use of infected tubers as planting material, as demonstrated for other yam viruses [ 8 ]. Since most YVY-infected plants reported in this work were coinfected with other viruses such as YMMV and YaV1 [ 8 , 10 ], we could not associate YVY with specific symptoms.…”

“…YVY might also be transmitted vertically through vegetative propagation and the use of infected tubers as planting material, as demonstrated for other yam viruses [ 8 ]. Since most YVY-infected plants reported in this work were coinfected with other viruses such as YMMV and YaV1 [ 8 , 10 ], we could not associate YVY with specific symptoms.…”