Black pepper (Piper nigrum) is a biotechnologically interesting plant, research target for both metabolism exploration and improvement related to phytopathological problems, in addition to understanding the evolution of basal angiosperms, ancestral group to which it belongs. With the technological revolution, the next generation sequencing offered access to genetic heritage of non model plants enabling the opening of new biotechnological perspective. The identification of non homologous genes restricted to certain species, called taxonomically restricted genes (TRGs), is a primary biotechnological target, especially in species and groups that are divergent and ancestral. This study aims to establish a method for TRGs identification from RNA-seq data and to validate the approach a dataset for black pepper. The method consists in filtering the transcripts in several stages, so that the annotated transcripts and false positives are removed, and the remaining data without molecular information are classified as potential TRGs. The application of this approach to a black pepper transcriptome dataset (35,631 transcripts) resulted in 22,661 transcripts annotated by similarity. The transcripts that were not annotated in this first analysis were processed in the TRAPID tool, resulting in 12,895 transcripts not annotated. The evaluation of transcripts for false positive detection resulted in 245 true transcripts that were analyzed for the presence of non-coding RNA, resulting in 204 unidentified transcripts. At the end of the method application 71 non annotated transcripts remained with coding regions of protein, indicating potential TRGs. The characterization of these potential TRGs in black pepper can provide new information about the molecular mechanism of this specie and perhaps elucidate pathways for the establishment of cultivars tolerant to disease.
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