Long non-coding RNAs in wild wheat progenitors

Abstract

Triticum urartu and Aegilops tauschii are the diploid progenitors of the hexaploid Triticum aestivum (AuAuBBDD), donors of the Au and D genome respectively. In this work we investigate the long noncoding RNAs (lncRNAs) component of the genomes of these two wild wheat relatives. Sixty-eight RNA-seq libraries generated from several organs and conditions were retrieved from public databases. We annotated and characterized 14,515 T. urartu and 20,908 Ae. tauschii bona-fide lncRNA transcripts that show features similar to those of other plant and animal counterparts. Thousands of lncRNAs were found significantly modulated in different organs and exhibited organ specific expression, with a predominant accumulation in the spike, fostering the hypothesis of their crucial role in reproductive organs. Most of the organ-specific lncRNAs were found associated with transposable elements (TEs), indicating the possible role of TEs in lncRNA origin, differentiation and function. The majority of T. urartu and Ae. tauschii lncRNAs appear to be species-specific; nevertheless, we found some lncRNAs conserved between the two wheat progenitors, highlighting the presence and conservation of exonic splicing enhancers sites in multi-exon conserved lncRNAs. In addition, we found cases of lncRNA conservation and their cis regulatory regions spanning the wheat pre-domestication and post-domestication period. Altogether, these results represent the first comprehensive genome-wide encyclopedia of lncRNAs in wild wheat relatives, and they provide clues as to the hidden regulatory pathway mediated by long noncoding RNAs in these largely unexplored wheat progenitors.