Pequenos RNAs servem como um amortecedor genético contra choqu genômico em híbridos interespecíficos e alopoliploides em Arabidopsis

Small RNAs serve as a genetic buffer against genomic shock in Arabidopsis interspecific hybrids and allopolyploids

Misook Ha a,b,c, Jie Lu a,b, Lu Tian a, Vanitharani Ramachandran d, Kristin D. Kasschau e, Elisabeth J. Chapman e, James C. Carrington e, Xuemei Chen d, Xiu-Ji e Wang f and Z. Jeffrey Chen a,b,c,g,1

+ Author Affiliations

aSection of Molecular Cell and Developmental Biology,

bInstitute for Cellular and Molecular Biology,

cCenter for Computational Biology and Bioinformatics, and

gSection of Integrative Biology, The University of Texas, Austin, TX 78712;

dDepartment of Botany and Plant Sciences, University of California, Riverside, CA 92521;

eCenter for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331; and

fState Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 5 Datun Road, Chaoyang District, Beijing 100101, China

Communicated by Wen-Hsiung Li, University of Chicago, Chicago, IL, and approved July 1, 2009 (received for review March 19, 2009)

Abstract

Small RNAs, including microRNAs (miRNAs), small interfering RNAs (siRNAs), and trans-acting siRNAs (tasiRNAs), control gene expression and epigenetic regulation. Although the roles of miRNAs and siRNAs have been extensively studied, their expression diversity and evolution in closely related species and interspecific hybrids are poorly understood. Here, we show comprehensive analyses of miRNA expression and siRNA distributions in two closely related species Arabidopsis thaliana and Arabidopsis arenosa, a natural allotetraploid Arabidopsis suecica, and two resynthesized allotetraploid lines (F1 and F7) derived from A. thaliana and A. arenosa. We found that repeat- and transposon-associated siRNAs were highly divergent between A. thaliana and A. arenosa. A. thaliana siRNA populations underwent rapid changes in F1 but were stably maintained in F7 and A. suecica. The correlation between siRNAs and nonadditive gene expression in allopolyploids is insignificant. In contrast, miRNA and tasiRNA sequences were conserved between species, but their expression patterns were highly variable between the allotetraploids and their progenitors. Many miRNAs tested were nonadditively expressed (deviating from the mid-parent value, MPV) in the allotetraploids and triggered unequal degradation of A. thaliana or A. arenosa targets. The data suggest that small RNAs produced during interspecific hybridization or polyploidization serve as a buffer against the genomic shock in interspecific hybrids and allopolyploids: Stable inheritance of repeat-associated siRNAs maintains chromatin and genome stability, whereas expression variation of miRNAs leads to changes in gene expression, growth vigor, and adaptation.

expression regulation microRNAs polyploidy hybrid vigor

Footnotes

1To whom correspondence should be addressed. E-mail: zjchen@mail.utexas.edu

Author contributions: Z.J.C. designed research; M.H., J.L., L.T., V.R., and E.J.C. performed research; M.H., K.D.K., J.C.C., X.C., and X.-J.W. contributed new reagents/analytic tools; M.H. and J.L. analyzed data; and M.H. and Z.J.C. wrote the paper.

The authors declare no conflict of interest.

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