January 15-19, 2011
Town & Country Convention Center
San Diego, CA
Christina R Quinn , Danilo D Fernando
MicroRNAs (miRNAs) are small, endogenous RNAs that regulate gene expression through cleavage of mRNAs and shown to be important in several processes including development and stress responses. Using a combination of experimental and bioinformatic approaches, our study has identified several miRNAs and their target genes and examined their expression patterns in germinated pine pollen. MiRNAs were cloned from germinated loblolly pine pollen and resulted in the identification of novel miRNAs. A miRNA microarray consisting of 635 unique plant miRNA sequences from miRBase detected 208 miRNAs in both ungerminated and germinated pollen. Six miRNAs were differentially expressed (p-value < 0.10); however, only one was upregulated in germinated pollen. Additionally, 14 miRNAs exhibited a fold change of two or greater, with 11 of these showing increased expression in germinated pollen. RT-PCR verified the expression patterns and localization of the 20 miRNAs. MiRNAs were computationally identified using known Arabidopsis miRNAs to search for homologs from the loblolly pine EST database. Of the potential miRNAs identified as homologous to Arabidopsis, many belong to families not yet reported for pine. For all candidate miRNAs, bioinformatics was used to derive the corresponding stem-loop structure and search for possible target mRNAs. This study expands the miRNA profile of loblolly pine and our understanding of the roles of miRNAs in pollen germination.