Rust resistance SH3 loci in Coffea spp.

Resistance to the leaf rust delivered by SH3 factor(s) from Coffea liberica is well-grounded as specially durable. We analyzed C. liberica SH3 genes, here described for the first time, and SH3 loci in other Coffea species, taking C. arabica cv. IAPAR59 as reference. All species display multiple SH3-RxCC-NBS-LRR variants. SH3-Rx proteins, charged with RanGAP2 co-factors and fungi effectors in the cytoplasm, potentially, target DNA directly to trigger defense. C. liberica SH3-RxCC-NBS-LRR set is large, comprising more orthologs to A. thaliana CAR1 and 'canonical' leucine repeats among diploids analyzed. Interestingly, genes sharing the loci with SH3-RxCC-NBS-LRRs are preserved and defense related.