The use of cysteine proteinase inhibitors to engineer resistance against
potyviruses in transgenic tobacco plants
Rafael Gutierrez-Campos1, Juan Antonio Torres-Acosta1, Luis Jorge Saucedo-Arias2
& Miguel Angel Gomez-Lim2
1
Departamento de Química, Centro Básico,
Universidad Autónoma de Aguascalientes, Ave. Universidad
940, C.P. 20 100, Aguascalientes, Ags.
México.
2
Departamento de Ingeniería Genética,
Centro de Investigación y Estudios Avanzados, Unidad Irapuato,
Apartado Postal 629, Irapuato, Mexico.
Correspondence should be addressed to Miguel Angel Gomez-Lim mgomez@irapuato.ira.cinvestav.mxgenetic engineeringtransgenic plantspotyvirustobacco etch virustobaccoproteinase inhibitorsvirus resistance
As the processing mechanism of all known potyviruses involves the activity
of cysteine proteinases, we asked whether constitutive expression of a rice
cysteine proteinase inhibitor gene could induce resistance against two important
potyviruses, tobacco etch virus (TEV) and potato virus Y (PVY), in transgenic
tobacco plants. Tobacco lines expressing the foreign gene at varying levels
were examined for resistance against TEV and PVY infection. There was a clear,
direct correlation between the level of oryzacystatin message, inhibition
of papain (a cysteine proteinase), and resistance to TEV and PVY in all lines
tested. The inhibitor was ineffective against tobacco mosaic virus (TMV) infection
because processing of this virus does not involve cysteine proteinases. These
results show that plant cystatins can be used against different potyviruses
and potentially also against other viruses, whose replication involves cysteine
proteinase activity.
