Characterization of transgenic plants expressing a Potato Virus X(PVX) RNA

BEY P., MENTABERRY A. AND ZELADA A.

Iguazú, Misiones, Argentina

Congreso; XL Reunión Anual de Sociedad Argentina de Investigación Bioquímica (S.A.I.B); 2004

Sociedad Argentina de Investigación Bioquímica

Plants are currently being used as a cost-effective and safe heterologous system for the expression of functional biomolecules. We have developed a PVX vector that allow to express the cDNA of the complete genome of PVX under the control of the 35S CaMV promoter. This viral vector was efficiently expressed in a transient system by agroinfiltration of Nicotiana tabacum leaves. We present here the characterization of N. tabacum plants transformed with the PVX vector. We have obtained two different transgenic lines named PVX1 and PVX2 confirmed by PCR and Southern blot. PVX2 present PVX infection symptoms while PVX1 has a healthy appearance. Western blot analysis revealed expression of viral capsid and the movement protein p24 only in PVX2, while no viral proteins were detected in PVX1. In spite of that, both transgenic lines were able to produce infective virions when the infectivity of PVX1 and PVX2 plant extracts was analysed. PVX1 plants infected with PVY, a virus that encodes a strong silencing suppressor, developed severe symptoms of infection and produced high levels of virions, suggesting that the low level of PVX in this line is due to post-transcritional silencing. To our knowledge, this is the first time that a PVX transgenic plant (the PVX2 line) produces high levels of virions, resembling an infected plant. Further studies will determine whether these results can be generally applied for high efficiency transgene expression in plants.