Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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A Genome-Wide Characterization of MicroRNA Genes in Maize

ABSTRACT: MicroRNAs (miRNAs) are small non-coding RNAs that play essential roles in plant growth and development. We conducted a genome-wide survey of maize miRNA genes, characterizing their structure, expression, and evolution. Computational approaches based on homology and secondary structure modeling identified 150 high-confidence genes within 26 miRNA families. For 25 families, expression was verified by deep-sequencing of small RNA libraries that were prepared from an assortment of maize tissues. PCR-RACE amplification of 68 miRNA transcript precursors, representing 18 families conserved across several plant species, showed that splice variation and the use of alternative transcriptional start and stop sites is common within this class of genes. Comparison of sequence variation data from diverse maize inbred lines versus teosinte accessions suggest that the mature miRNAs are under strong purifying selection while the flanking sequences evolve equivalently to other genes. Since maize is derived from an ancient tetraploid, the effect of whole-genome duplication on miRNA evolution was examined. We found that, like protein-coding genes, duplicated miRNA genes underwent extensive gene-loss, with ~35% of duplicate homeologous miRNA genes retained. This number is higher than that observed with protein-coding genes. A search for putative miRNA targets indicated a bias towards genes in regulatory and metabolic pathways. As maize is one of the principal models for plant growth and development, this study will serve as a foundation for future research into the functional roles of miRNA genes. Surveying miRNA genes in 5 maize tissues (root, seedling, tassel, ear, and pollen) by sequencing small RNA libraries using the Illumina Genome Analyzer

ORGANISM(S): Zea mays

SUBMITTER: Jer-M Chia

PROVIDER: E-GEOD-17943 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

A genome-wide characterization of microRNA genes in maize.

Zhang Lifang L Chia Jer-Ming JM Kumari Sunita S Stein Joshua C JC Liu Zhijie Z Narechania Apurva A Maher Christopher A CA Guill Katherine K McMullen Michael D MD Ware Doreen D

PLoS genetics 20091120 11

MicroRNAs (miRNAs) are small, non-coding RNAs that play essential roles in plant growth, development, and stress response. We conducted a genome-wide survey of maize miRNA genes, characterizing their structure, expression, and evolution. Computational approaches based on homology and secondary structure modeling identified 150 high-confidence genes within 26 miRNA families. For 25 families, expression was verified by deep-sequencing of small RNA libraries that were prepared from an assortment of ...[more]

PMID: 19936050

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Project description:In plants, MicroRNAs (miRNAs) are a new class of endogenous small RNAs that play essential regulatory roles in plant growth, development and stress response. Extensive studies of miRNAs have been performed in model plants such as rice, Arabidopsis thaliana and other plants. However, the number of miRNAs discovered in maize is relatively low and little is known about miRNAs involved in the four stages during maize ear development. Here, we use deep-sequencing, miRNA microarray assays and computational methods to identify, proM-oM-,M-^Ale, and describe conserved and non-conserved miRNAs at four developmental stages. A total of 27 conserved miRNA families were identiM-oM-,M-^Aed in all four stages, In addition to known miRNAs, we also found 23 new maize-specific miRNAs together with their star strands. We have also shown that almost all of them originated from single genes. We have found that many known and new miRNAs showed temporally expression. Finally, a total of 251 transcripts (140 genes) targeted by 102 small RNAs including 98 miRNAs and 4 ta-siRNAs were identified by genomic-scale high-throughput sequencing of miRNA cleaved mRNAs.This study led to the confirmation of the authenticity of 27 conserved miRNA families and the discovery of 23 novel miRNAs in maize. In addition, we have identified 130 targets of known and new miRNAs and ta-siRNA using recently developed tools for the global identification of miRNA targets. Identification and characterization of this important class of regulatory genes in maize may improve our understanding of molecular mechanism controlling flower development. The seeds of maize inbred line B73 were first sterilized and germinated in an incubator, then grown in a controlled environment with 28M-BM-0C/21M-BM-0C (day/night) under a 16-h day/8-h night photoperiod with a relative humidity of 70%. Ear development can be divided into four stages: the growth point elongation phase, spikelet differentiation phase, the floret primordium differentiation phase and floret organ differentiation phase. Plant materials (ears) were collected as described previously. In brief, ears were manually collected at the four developmental stages according to the plant features (number of visible leaves, leaf age index, and number of unfolded and folded leaves) combined with microscopic observation.

Project description:Small non-coding RNAs (sRNAs) play key roles in plant development, growth and responses to biotic and abiotic stresses. At least four classes of sRNAs have been well characterized in plants, including repeat-associated siRNAs (rasiRNAs), microRNAs (miRNAs), trans-acting siRNAs (tasiRNAs) and natural antisense transcript-derived siRNAs. Chinese fir (Cunninghamia lanceolata) is one of the most important coniferous evergreen tree species in China. No sRNA from Chinese fir has been described to date. To obtain sRNAs in Chinese fir, we sequenced a sRNA library generated from seeds, seedlings, leaves, stems and calli, using Illumina high throughput sequencing technology. A comprehensive set of sRNAs were acquired, including conserved and novel miRNAs, rasiRNAs and tasiRNAs. With BLASTN and MIREAP we identified a total of 115 conserved miRNAs comprising 40 miRNA families and one novel miRNA with precursor sequence. The expressions of 16 conserved and one novel miRNAs and one tasiRNA were detected by RT-PCR. Utilizing real time RT-PCR, we revealed that four conserved and one novel miRNAs displayed developmental stage-specific expression patterns in Chinese fir. In addition, 209 unigenes were predicted to be targets of 30 Chinese fir miRNA families, of which five target genes were experimentally verified by 5' RACE, including a squamosa promoter-binding protein gene, a pentatricopeptide (PPR) repeat-containing protein gene, a BolA-like family protein gene, AGO1 and a gene of unknown function. We also demonstrated that the DCL3-dependent rasiRNA biogenesis pathway, which had been considered absent in conifers, existed in Chinese fir. Furthermore, the miR390-TAS3-ARF regulatory pathway was elucidated. We unveiled a complex population of sRNAs in Chinese fir through high throughput sequencing. This provides an insight into the composition and function of sRNAs in Chinese fir and sheds new light on land plant sRNA evolution. The aim of this study is to investigate the small RNA transcriptome in Cunninghamia lanceolata. Total RNAs of seeds and calli were extracted using RNAiso-mate for plant tissue and RNAiso plus (Takara, Dalian, Liaoning, China), whereas total RNAs of seedlings, adult leaves and stems were isolated with the Concert Plant RNA Reagent (Invitrogen, Carlsbad, CA, USA), and were then treated with RNase-free DNase I (Promega, Madison, WI, USA). Equal amount of total RNAs from the 5 different samples were mixed to form a single RNA pool. Twenty micrograms of total RNAs from the pool were used and 16 to 30-nt sRNAs were purified using Novex 15% TBE-¬Urea gel (Invitrogen). Two adaptors were sequentially ligated to the 5' and 3' ends of purified sRNAs. The ligation products were further purified from Novex 10% TBE-Urea gel. Reverse transcriptase SuperScript II (Invitrogen) and high-fidelity DNA polymerase Phusion (New England Biolabs, Ipswich, MA, USA) were used in the following RT-PCR reaction. The amplification products were cut from Novex 6% TBE-Urea gel. The purified DNA fragments were used for sequencing on an Illumina 1G Genome Analyzer at the Beijing Genomics Institute, Shenzhen, China.

Dataset Information

A Genome-Wide Characterization of MicroRNA Genes in Maize

Publications

A genome-wide characterization of microRNA genes in maize.

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