小中大原始出处：
The Plant Cell April 17, 2009; 10.1105/tpc.109.065714
Genome-Wide and Organ-Specific Landscapes of Epigenetic Modifications and Their Relationships to mRNA and Small RNA Transcriptomes in Maize
Xiangfeng Wang 1, Axel A. Elling 2, Xueyong Li 3, Ning Li 4, Zhiyu Peng 5, Guangming He 6, Hui Sun 2, Yijun Qi 6, X. Shirley Liu 7, and Xing Wang Deng 8*
1 Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China; National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520; Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, Massachusetts 02115
2 Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520
3 National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520
4 Beijing Genomics Institute at Shenzhen, Shenzhen 518083, China
5 Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China; Beijing Genomics Institute at Shenzhen, Shenzhen 518083, China
6 National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China
7 Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, Massachusetts 02115
8 Peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology, College of Life Sciences, Peking University, Beijing 100871, China; National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520
* To whom correspondence should be addressed.
Maize (Zea mays) has an exceptionally complex genome with a rich history in both epigenetics and evolution. We report genomic landscapes of representative epigenetic modifications and their relationships to mRNA and small RNA (smRNA) transcriptomes in maize shoots and roots. The epigenetic patterns differed dramatically between genes and transposable elements, and two repressive marks (H3K27me3 and DNA methylation) were usually mutually exclusive. We found an organ-specific distribution of canonical microRNAs (miRNAs) and endogenous small interfering RNAs (siRNAs), indicative of their tissue-specific biogenesis. Furthermore, we observed that a decreasing level of mop1 led to a concomitant decrease of 24-nucleotide siRNAs relative to 21-nucleotide miRNAs in a tissue-specific manner. A group of 22-nucleotide siRNAs may originate from long-hairpin double-stranded RNAs and preferentially target gene-coding regions. Additionally, a class of miRNA-like smRNAs, whose putative precursors can form short hairpins, potentially targets genes in trans. In summary, our data provide a critical analysis of the maize epigenome and its relationships to mRNA and smRNA transcriptomes.
