Begin at the Beginning: A BAC-End View of the Passion Fruit (Passiflora) Genome

The passion fruit (Passiflora edulis) is a tropical crop of economic importance both for juice production and consumption as fresh fruit. However, very little is known about the genome of the species. Therefore, improving our understanding of passion fruit genomics is essential and to some degree a pre-requisite if its genetic resources are to be used more efficiently. In this study, we have constructed a large-insert BAC library and provided the first view on the structure and content of the passion fruit genome, using BAC-end sequence (BES) data as a major resource. The library consisted of 82,944 clones, with an average insert size of 108 kb and a coverage of ~6 haploid genome equivalents. We explored 10,000 BES and we identified reads likely to contain repetitive mobile elements (18.4%), microsatellites (1.1%) and putative proteins (9.6%). Based on BlastX analyses, 960 sequences were found to have high levels of similarity to plant proteins and ontological terms were assigned to 507 of them. The vast majority of the top-hits made by our sequences were to Populus trichocarpa (24.8%), Theobroma cacao (21.6%), Ricinus communis (14.3%) and Vitis vinifera (6.5%). A number of BAC-end pair sequences could be mapped to intervals of the sequenced Arabidopsis thaliana, V. vinifera and P. trichocarpa chromosomes, and putative collinear microsyntenic regions were identified. Concluding, we generated the first large-insert library for a member of Passifloraceae. This BAC library represents a valuable tool for future whole genome study.

Financial support: FAPESP