De novo assembly of the sweet pitaya (Stenocereus thurberi) fruit peel transcriptome and identification of cuticle biosynthesis genes

Stenocereus thurberi is a cactus endemic to the Sonoran desert (Mexico), which produces a fruit named sweet pitaya. One trait that allows the cactus to survive in desert ecosystems is its cuticle, which limits water loss in dry conditions. Nevertheless, the mechanism of cuticle biosynthesis has yet to be described for cactus fruits. Also, transcripts from S. thurberi published in the databases are scarce. This study reports the de novo assembly of the sweet pitaya peel transcriptome. The assembly includes 174,449 transcripts with an N50 value of 2,110 bp. Out of the total transcripts, 43,391 were classified as long non-coding RNA. Functional categorization analysis suggests that mechanisms of response to stress and cuticle biosynthesis are carried out in fruit pitaya peel. The transcripts coding for a cytochrome p450 77A (StCYP77A), Gly-Asp-Ser-Leu motif lipase/esterase 1 (StGDSL1), and ATP binding cassette G 11 (StABCG11), which carried out the synthesis, polymerization, and transport of cuticle components, respectively, were identified. Expression analysis during fruit development suggests an active cuticle biosynthesis at the early stages and the ripe stages, carried out by StCYP77A, StGDSL1, and StABCG11. The dataset generated here will help to improve the elucidation of the molecular mechanism of cuticle biosynthesis in S. thurberi and other cactus fruits.