Polyribozyme capable of conferring on plants resistance to viruses and resistant plants producing this polyribozyme

A polyribozyme having endoribonuclease activity and which inactivates the capsid protein gene of a plant virus, wherein the polyribozyme comprises a plurality of ribozymes, each of which cleaves the capsid protein gene or its corresponding transcript, or its corresponding replication intermediate, wherein each ribozyme comprises a catalytic portion and two hybridizing arms that are complementary to a portion of the capsid protein gene of the plant virus,

• wherein the plant virus is selected from the group consisting of:
• the Caulimoviruses, the Geminiviruses, the Reoviridae, the Rhabdoviridae, the Tobamoviruses, the Potexviruses, the Potyviruses, the Carlaviruses, the Closteroviruses, the Tobraviruses, the Hordeiviruses, the Tymoviruses, the Barley Yellow Dwarf Virus, the Tombusviruses, the Sobemoviruses, the Neopviruses, the Comoviruses, the Cucumoviruses, the Bromoviruses, and the Ilarviruses.