The P1 gene of Cauliflower mosaic virus is responsible for breaking resistance in Arabidopsis thaliana ecotype Enkheim (En-2).

Abstract Arabidopsis thaliana ecotype En-2 is resistant to several strains of Cauliflower mosaic virus (CaMV), including strain W260, but is susceptible to strain NY8153. Resistance in En-2 is conditioned by a single, semi-dominant gene called CAR 1. We constructed several recombinant infectious clones between W260 and NY8153 and evaluated their capability to infect En-2. This analysis showed that the capacity of NY8153 to break resistance in En-2 was conditioned by mutations within the CaMV gene 1, a gene that encodes a protein dedicated to cell-to-cell movement (P1), and conversely, that P1 of W260 is responsible for eliciting the plant defense response. A previous study had shown that P6 of W260 was responsible for overcoming resistance in Arabidopsis ecotype Tsu-0 and that P6 of CaMV strain CM1841 was responsible for triggering resistance. The present study now shows that a second gene of CaMV is targeted by Arabidopsis for plant immunity. Highlights • The Arabidopsis CAR1 resistance gene in ecotype En-2 specifies resistance to CaMV. • Unlike most CaMV strains, NY8153 is able to infect En-2 systemically. • We now show that gene 1 of CaMV strain NY8153 overcomes resistance of CAR1. • Thus, gene 1 of other CaMV strains must either be defective of elicit plant defenses. [ABSTRACT FROM AUTHOR]