Project description:Allopolyploidy is long recognized as an essential driving force in plant evolution. Recent studies have demonstrated that small RNAs, including microRNAs (miRNAs), play important roles in the process of allopolyploidy. However, the question that how the distinct parent-of-origin miRNAs are maintained in allopolyploids and how these small RNAs affect gene expression and phenotypes remain to be answered. Therefore, we investigated the miRNA expression profiles of a synthesized allotetraploid, Cucumis ×hytivus and its parents. The different developmental stages of leaves of C. ×hytivus showing contrasting leaf colour were compared as well. Following high-throughput sequencing, 546 conserved and 287 novel miRNAs were identified. The expression levels of nine miRNAs obtained by quantitative real-time PCR were consistent with the sequencing results. We detected that 15 miRNAs were divergently expressed between the parent species, and 23 miRNAs were differentially expressed in C. ×hytivus compared to either of its parents or both, which suggests the significant effect of allopolyploidization on miRNAs accumulation. Additionally, 26 conserved and 13 novel miRNAs differed in expression between the young and mature leaves of C. ×hytivus, indicating an essential role of miRNA-mediated regulation of leaf development following allopolyploidization. This study enriches the context of allopolyploidy effect on miRNAs and lays a foundation for the elucidation of the miRNA-mediated regulatory mechanism in phenotypic variation in allopolyploids.
Project description:Changes to gene expression and splicing are investigated between parental species (B. oleracea and B. rapa) and three resynthesized allopolyploids, as well as a natural B. napus
Project description:How allopolyploids are able not only to cope but profit from their condition is a question that remain elusive, but of great importance within the wide context of successful hybrid polyploid evolution. One outstanding example of successful allopolyploidy is the endemic Iberian S. alburnoides fish complex. Previously, based on the evaluation of 7 genes, it was reported that the transcription levels between diploid and triploid hybrid S. alburnoides were similar. If this phenomenon would occur on a full genomic scale, a wide functional diploidization could be related to the success of polyploids. We generated RNA-seq data from whole juvenile fish and from an adult tissue, to perform the first comparative quantitative transcriptomic analysis between ploidy levels of a vertebrate allopolyploid. We found 64% in juvenilesM-b full body samples and 44% in liver samples of similar expression between diploid and triploid hybrids, and those genes are mostly involved in processes of basal biological maintenance of the cells. Yet, respectively only 29% and 15% of transcripts presented accurate dosage compensation. Therefore, an exact functional diploidization of the triploid genome does not occur, but globally a significant down regulation of gene expression in triploids was observed. We find that for those genes which show similar expression levels in diploids and triploids, expression in triploids is not globally strictly proportional to gene dosage nor is it set to a perfect diploid level. This quantitative flexibility of expression may be a strong contributor to overcome the 'genomic shock', and be an immediate evolutionary advantage of allopolyploids. Genotypes: Squalius alburnoides is an allopolyploid cyprinid, resulting from interspecific hybridization between females of Squalius pyrenaicus (P genome) and males of a now extinct species related to Anaecypris hispanica (A genome). S. alburnoides natural populations arecomposed of animals of different ploidy levels and genomic constitutions (different genotypes). The predominant S. alburnoides complex intervenients in the Iberian Peninsula southern rivers are the hybrid triploid PAA, diploid PA, the parental-like diploid AA and the parental species S. pyrenaicus PP.
Project description:MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) are produced in diverse species and control gene expression and epigenetic regulation. Although physiological and developmental roles of miRNAs and siRNAs have been extensively studied in plants and animals, expression diversity and evolution of miRNAs and siRNAs in closely related species are poorly understood. Here we report comprehensive analyses of miRNA expression and siRNA distribution in two closely related species (Arabidopsis thaliana and A. arenosa), a natural allotetraploid (A. suecica), and two resynthesized allotetraploid lines (F1 and F7) derived from A. thaliana and A. arenosa. The siRNA populations present in A. thaliana were maintained in resynthesized allotetraploids and A. suecica. Although miRNA sequences were highly conserved, their expression patterns were highly variable between the allotetraploids and their progenitors. Significantly, many miRNAs were nonadditively expressed in the allotetraploids relative to the parents and preferentially degraded A. thaliana or A. arenosa targets. Stable inheritance of parental siRNAs in allopolyploids helps maintain genome stability in response to “genomic shock”, whereas expression diversity of miRNAs and their target preference lead to interspecies variation in gene expression, growth, and development. NOTE: sff files unavailable for Samples AaL and F1L.