| description |
Although closely related to plant evolution, polyploid sRNAs (small RNAs) were seldom studied with experiments, especially on genome-wide range. In this study, a rice twin-seeding (two seedlings from the same grain) line SARII-658 was employed to isolate autotriploids. Those autotriploids possess unique merits to study the two interesting topics: (i) natural polyploids; (ii) the autonomy of epigenetic variations (i.e. sRNAs) from genome doubling per se. sRNA libraries were prepared from those diploid-autotriploid twin-seedlings and then were sequenced to produce 13,308,226 short sequence reads in total. Out of the 35,429 miRNA genes and siRNA clusters, 1,547 (4.36%) changed their expression levels for two folds or above after genome doubling (thereinafter, referred those sRNAs as ploidy-sensitive). The expression-unregulated sRNAs (3.71%) were far more than the downregulated ones (0.64%), suggesting that the negative regulation of the coding gene by sRNA increase is more prevalent than the positive regulation during genome doubling. The expression of sRNAs were obviously increased and biased to accumulate toward centromeric and heterochromatic regions, suggesting that sRNAs should play a role in repressing transposition activity during genome doubling. Except transposition activity, the targets of those ploidy-sensitive sRNAs involved many kinds of gene function categories, suggesting an overall regulation of sRNAs to polyploid biological processes. Findings from this study will provide theoretical bases for elucidating epigenetic mechanism of plant and sRNA evolution via genome doubling.Overall design: Examination of 2 different small RNA expression profilings in 2 ploidy plants. |