AvrLm4-7 is found in Leptosphaeria maculans, an ascomycete fungus in the dothideomycete group which is responsible for stem canker (blackleg) of Brassica napus (oilseed rape, OSR) and other crucifers. AvrLm4-7 is one of six avirulence genes which encodes a small secreted protein strongly over-expressed at the onset of plant infection. This gene confers a dual recognition specificity by two distinct resistance genes of OSR, Rlm4 and Rlm7 and loss of AvrLm4 avirulence was demonstrated to be associated with a strong fitness cost. Structure and functional analysis of AvrLm4-7 protein show that it contains the motifs RAWG and RYRE, part of a well-structured protein region held together by disulfide bridges. Mutations in the RAWG motif or in the RYRE motif (especially mutations in both motifs) almost abolished the translocation of AvrLm4-7 into cells. Furthermore, loss of recognition of AvrLm4-7 by Rlm4 is caused by the mutation of a single glycine to an arginine residue located in a loop of the protein [1].

1: Crystal structure of the effector AvrLm4-7 of Leptosphaeria maculans reveals insights into its translocation into plant cells and recognition by resistance proteins. Blondeau K, Blaise F, Graille M, Kale SD, Linglin J, Ollivier B, Labarde A, Lazar N, Daverdin G, Balesdent MH, Choi DH, Tyler BM, Rouxel T, van Tilbeurgh H, Fudal I; Plant J. 2015;83:610-624. PMID:26082394