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. Our study has identified several miRNAs and their target genes and examined their expression patterns in germinated pine pollen. A miRNAarray consisting of 635 unique plant miRNA sequences from miRBase was used to establish the expression of known miRNAs in germinated pine pollen. Of the 653 miRNAs, 208 were detected in both ungerminated and germinated pollen. Six miRNAs showed significant differential expression (p-value < 0.10), but only one was upregulated in germinated pollen. In addition, 14 miRNAs exhibited a fold change of two or greater, with 11 of these showing increased expression in germinated pollen. Bioinformatics was used to derive the corresponding stem-loop structure for each miRNA and search for possible target mRNAs. RT-PCR verified the expression patterns and localization of the 20 miRNAs. Some of the miRNAs are involved in the regulation of transcription factors, such as Squamosa Promoter Binding Protein, and of mRNAs coding for the AGO protein and signaling molecules. In other experiments, cloning resulted in the identification of novel miRNAs from germinated pollen. Functional analysis will be done to establish the functions these unique miRNAs in pine pollen germination. Bioinformatics has identified many miRNAs homologous to Arabidopsis miRNAs, many of which belong to families not yet reported for pine. This study expands the miRNA profile of loblolly pine and our understanding of how miRNAs are involved in pollen germination.