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Open Access Highly Accessed Research article

MicroRNA and tasiRNA diversity in mature pollen of Arabidopsis thaliana

Robert Grant-Downton1, Gael Le Trionnaire2, Ralf Schmid3, Josefina Rodriguez-Enriquez4, Said Hafidh2, Saher Mehdi1, David Twell2 and Hugh Dickinson1*

Author Affiliations

1 Department of Plant Sciences, South Parks Rd, Oxford OX1, 3RB, UK

2 Department of Biology, University of Leicester, Leicester, LE1 7RH, UK

3 Department of Biochemistry, University of Leicester, Leicester, LE1 7RH, UK

4 Instituto Antonio González, Universidad de La Laguna, 38206 La Laguna, Santa Cruz de Tenerife, Spain

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BMC Genomics 2009, 10:643  doi:10.1186/1471-2164-10-643

Published: 30 December 2009

Abstract

Background

New generation sequencing technology has allowed investigation of the small RNA populations of flowering plants at great depth. However, little is known about small RNAs in their reproductive cells, especially in post-meiotic cells of the gametophyte generation. Pollen - the male gametophyte - is the specialised haploid structure that generates and delivers the sperm cells to the female gametes at fertilisation. Whether development and differentiation of the male gametophyte depends on the action of microRNAs and trans-acting siRNAs guiding changes in gene expression is largely unknown. Here we have used 454 sequencing to survey the various small RNA populations present in mature pollen of Arabidopsis thaliana.

Results

In this study we detected the presence of 33 different microRNA families in mature pollen and validated the expression levels of 17 selected miRNAs by Q-RT-PCR. The majority of the selected miRNAs showed pollen-enriched expression compared with leaves. Furthermore, we report for the first time the presence of trans-acting siRNAs in pollen. In addition to describing new patterns of expression for known small RNAs in each of these classes, we identified 7 putative novel microRNAs. One of these, ath-MIR2939, targets a pollen-specific F-box transcript and we demonstrate cleavage of its target mRNA in mature pollen.

Conclusions

Despite the apparent simplicity of the male gametophyte, comprising just two different cell types, pollen not only utilises many miRNAs and trans-acting siRNAs expressed in the somatic tissues but also expresses novel miRNAs.