S01 - Session P2 - Some Coffea liberica SH3-LRR-coding sequences are highly distinguishable

Authors: Paula C. da S. Angelo *, Luiz Filipe P. Pereira, Gustavo H. Sera, Eveline T. Caixeta

Genes in the SH3 locus are involved in the interaction with the fungus Hemileia vastatrix. Previously we found, by comparison to data published for Coffea arabica cv. IAPAR59, that the SH3 loci are multi-alellic and complex in C. arabica var. Caturra, C. eugenioides and C. canephora publicly available genomes. The above cited SH3 loci hold different numbers of copies of a CC-NBS-LRR gene in distinctive organizations. C. liberica is considered to display the SH3 ideal configuration providing durable resistance to coffee leaf rust, which is highly desirable, hence pursued in breeding. The coffee CC-NBS-LRR genes allocated to the SH3 loci display highly conserved as well as hypervariable regions. So, sets of primers designated to amplify the hypervariable LRR-carboxy terminals were used to clone and sequence SH3 variants in C. liberica and 'IAPAR59'. Sanger sequencing was used to access the cloned variants and neighbor-joining was used to represent pairwise divergence indexes between the sequences. 'IAPAR59' was re-accessed as a testimonial for the effectiveness of the approach because it was possible to verify that all the variants for the SH3 genes in 'IAPAR59' BAC clones already reported elsewhere, were also cloned using our primer sets. Indeed, it was considered that all the variants present in the accessed C. liberica plant had been cloned too. This was checked by contrasting the restriction fragment maps generated from genomic DNA x cloned amplicons in the two genotypes: patterns for both DNA sources of a same genotype were equal, and diverged from those in the other genotype. Regarding sequences, at least three out of six carboxy-terminal variants found in C. liberica seem to be exclusive when contrasted to the other four genotypes accessed. Differences found in the restriction maps and sequences are very likely related to susceptibility or resistance reactions verified during [coffee plants - H. vastatrix physiological races] interactions.