Fecha de publicación: -- Fuente: WIPO "tomato" The present invention relates to a trans-complementary system for heterologous expression of genes in plants and comprises a producer vector and a helper vector whereas I) said producer vector is incapable for at least one function needed to cause systemic infection in plants e.g., either by replication, cell-to-cell and/or long distance movement, and II) the helper vector completes the missing function in tandem. Certain producer and helper vectors in one trans-complementary system are derived from the same virus, or certain producer and helper vectors in one trans-complementary system are derived from different plant viruses. The present invention also provides methods of use, e.g., to improved yield of the heterologous proteins expressed notably in crop plants, and the ease of use of said system.