A draft genome assembly of “Cas” (Psidium friedrichsthalianum (O. Berg) Nied.): an indigenous crop of Costa Rica untapped

Psidium friedrichsthalianum (O. Berg) Nied. is a tropical tree species in the Myrtaceae family, natively distributed from southern Mexico to eastern Venezuela and Ecuador and commonly known as "Cas'', "Costa Rican guava" or “Sour Guava”. The “Cas” produces a fruit with a rather distinctive acidic flavor and has bioactive compounds with biological potential equal or greater than common Guava; is considered an indigenous crop in Costa Rica with characteristics as a functional food untapped. This species has not been completely domesticated, and can be found in home gardens, paddocks, small groups, and, more recently, in small and medium sized plantations. Also, the plantations of this species do not have technical and scientific support or agronomic promotion from industry, nor are there genetic resources or germplasm readily available to farmers. This limits its commercial development and the implementation of selection or genetic improvement programs. In this study, we present the first draft assembly of the Cas genome using PacBio long reads and the Canu assembly pipeline. Our draft assembly has a total length of 417.64 Mb, with 24 440 contigs and a N50 contig size of 21.3 Kb. Structural annotation resulted in 59 036 gene models. Functional annotation was conducted against the non-redundant set of genes from the KEGG database. Of the 52 422 complete genes models, 15.55% (8 153) presented homology with KEGG orthologs. The genes found in our Cas draft assembly were compared to those found in Eucalyptus grandis W. Hill. in the KEGG repository. According to the KEGG pathway assignments, 33 isoforms were annotated as part of the flavonoid biosynthetic pathway. In addition, 19 isoforms were annotated as part of phenylpropanoid biosynthetic pathway. The results of this study provide an overview of the first draft of the Cas genome assembly using PacBio long reads. This new genomic resource represents the basis for exploring the genetic potential of this crop with characteristics as a functional food.