LECOQ, H., INRA, Station de Pathologie Végétale, B P 94, Montfavet, 84143, France
RAVELONANDRO, M., INRA, Station de Pathologie Végétale, La Grande Ferrade, B P 81, Villenave D'Ornon, 33883, France
WIPF‐SCHEIBEL, C., INRA, Station de Pathologie Végétale, B P 94, Montfavet, 84143, France
MONSION, M., INRA, Station de Pathologie Végétale, La Grande Ferrade, B P 81, Villenave D'Ornon, 33883, France
RACCAH, B., Department of Virology, Aro, The Volcani Center, P. O. B. 6, Bet Dagan, 50250, Israel
DUNEZ, J., INRA, Station de Pathologie Végétale, La Grande Ferrade, B P 81, Villenave D'Ornon, 33883, France

Transgenic Nicotiana benthamiana plants expressing the coat protein of an aphid‐transmissible strain of plum pox potyvirus (PPV‐D) were infected with an aphid non‐transmissible strain of another potyvirus, zucchini yellow mosaic potyvirus (ZYMV‐NAT). Non‐viruliferous Myzus persicae could acquire and transmit ZYMV‐NAT from these plants but not from infected N. benthamiana control plants (not transformed, or transformed by the vector alone). Immunosorbent electron microscopy experiments using the decoration technique revealed that ZYMV‐NAT virus particles in the infected transgenic plants expressing the PPV coat protein could be coated not only with ZYMV antibodies but also, on segments of the particles, with PPV antibodies. This suggests that aphid transmission of ZYMV‐NAT occurred through heterologous encapsidation, and reveals a potential risk of releasing genetically engineered plants expressing viral coat proteins into the environment. Copyright © 1994, Wiley Blackwell. All rights reserved