title: Characterization and expression patterns of small RNAs in synthesized Brassica hexaploids.
abstract: Polyploidy has played an important role in promoting plant evolution through genomic merging and doubling. We used high-throughput sequencing to compare miRNA expression profiles between Brassica hexaploid and its parents. A total of 613, 784 and 742 known miRNAs were identified in Brassica rapa, Brassica carinata, and Brassica hexaploid, respectively. We detected 618 miRNAs were differentially expressed (log(2)Ratio ≥ 1, P ≤ 0.05) between Brassica hexaploid and its parents, and 425 miRNAs were non-additively expressed in Brassica hexaploid, which suggest a trend of non-additive miRNA regulation following hybridization and polyploidization. Remarkably, majority of the non-additively expressed miRNAs in the Brassica hexaploid are repressed, and there was a bias toward repression of B. rapa miRNAs, which is consistent with the progenitor-biased gene repression in the synthetic allopolyploids. In addition, we identified 653 novel mature miRNAs in Brassica hexaploid and its parents. Finally, we found that almost all the non-additive accumulation of siRNA clusters exhibited a low-parent pattern in Brassica hexaploid. Non-additive small RNA regulation is involved in a range of biological pathways, probably providing a driving force for variation and adaptation in allopolyploids.
authors.affiliation: State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
authors.forename: Yanyue
authors.initials: Y
authors.lastname: Shen
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Wenliang
authors.initials: W
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Gao
authors.forename: Jinling
authors.initials: J
authors.lastname: Meng
authors.forename: Jianbo
authors.initials: J
authors.lastname: Wang
mesh_terms: D001937:Brassica / Q000235:genetics*; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D035683:MicroRNAs / Q000235:genetics*; D011123:Polyploidy; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D035683:MicroRNAs; D018749:RNA, Plant