Assembly and characterization of the complete chloroplast genome of the Colombian coffee varieties Caturra Chiroso, Bourbon Chiroso and Chiroso, Coffea arabica L. (Rubiaceae), with insights on their phylogenetic relationships

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Varieties represent a defined group with differentiated characteristics derived through natural selection and/or selective breeding from within a species. In the Central-Andean region of Colombia (Urrao) there are three endemic varieties of the species Coffea arabica L [“Caturra Chiroso” (CCH), “Bourbon Chiroso” (BCH), and “Chiroso” (CHCH)], known as “Chiroso” group, globally renowned for their high quality and distinctive cup profile. Despite its significance, there is a lack of reported genomic resources or basic biological information for these. In this study, we conducted the first assembly and characterization of the complete chloroplast (Cp) genomes of these varieties and reconstructed their ancestry relationships. The Cp genomes were 155,188 bp in length (A = 30.93%; C = 19.06%; G = 18.37%; T = 31.64%); containing 131 genes, comprising 86 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. They consisted of four subregions: the large single-copy (LSC) region (85,159 bp; 83 genes), the short single-copy (SSC) region (18,136 bp; 12 genes), and the inverted repeats IRA (25,944 bp; 18 genes) and IRB (25,945 bp; 18 genes). Likewise, among 26 intraspecific varieties analyzed, CCH + BCH formed a unique haplotype, and CHCH + Bourbon + Caturra formed another. CCH and BCH featured an exclusive Cytosine mutation (SNP: C/A), position 47,413 bp (intergenic spacer region trnT(UGU)-trnL(UAA)]. Likewise, a total of 445 short tandem repeats were found in the Cp genomes (dinucleotides: 370; trinucleotides: 71; tetranucleotides: 1). Finally, the three formed a well-supported monophyletic group with conspecific varieties, being more closely related to Eastern Ethiopian-origin varieties [e.g. Berbere region], as well as with traditional ones like Typica, Bourbon, and Caturra. These coffee varieties are a valuable new genetic resource for use as a gene source for genetic improvement, biotechnology, direct exploitation and cultivation worldwide.