Mise en évidence de la présence du virus de la Mosaique de l'igname (YMV) en Guyane

Des echantillons d'ignames Dioscorea trifida collectes en Guyane francaise presentent des symptomes de mosaique en aretes de poisson. On montre que ces plantes contiennent un potyvirus flexueux, produisant des inclusions cytoplasmiques de type pinwheels et transmis par pucerons sur le mode non persistant. L'isolat etudie est proche du Yam Mosaic Virus decrit en Cote d'Ivoire, il reagit avec un antiserum anti-YMV- Cote d'Ivoire et sa proteine capside presente une mobilite electrophoretique identique, mais il produit des symptomes plus marques sur Nicotiana benthamiana et presente une mobilite electrophoretique differente de celle d'isolats provenant de Guadeloupe (FWI); Des precautions doivent etre prises pour eviter tout echange international de materiel infecte. ----- Yam plants, Dioscorea trifida, collected in French Guyana showed chromatic fish -bone symptoms on their leaves. The plants were found infected by a potyvirus with flexuous rods, produccing pinwheels in infected cytoplasm, transmitted mechanically and buy aphids in a non persisten manner. The virus reacted with an antiserum prepared against the Ivory Coast isolate of Yam Mosaic Virus an their coat proteins presented the same electrophoretic mobility. Differences in electrophoretic mobility were found with a yam potyvirus collected in Guadeloupe (FWI); the guyana isolate produced also a more severe vein-banding on Nicotiane benthammiana leaves than the other Yam isolates. Precautions must be taken in order to avoid any international exchange of infected material.