microRNA Expression Profiles Associated with Vegetative Bud Initiation and Development in Populus

In poplar, reproductive and vegetative growth is regulated by the FLOWERING LOCUS T (FT) FT1 and FT2 genes. FT1 promotes flowering in response to winter temperatures, whereas FT2 promotes vegetative growth and inhibition of bud set in response to warm temperatures and long days in the growing season. The functional divergence of FT1 and FT2 was associated with a shift in their expression profiles and a divergence of their corresponding gene networks. MicroRNAs regulate gene expression and as such they play a key role in plant development. To identify miRNAs involved in vegetative bud growth, we analyzed the expression of plant miRNAs (miRBase, release 18) during the time course of bud development using microarrays. miRNAs differentially expressed (DEMs) at different stages of bud development were identified and their targets predicted. We also analyzed Affymetrix expression data of protein encoding genes previously generated by our group. Genes differentially expressed were identified and mapped to regulation networks. The role of miRNAs in vegetative bud initiation and development was analyzed by correlating the expression of DEMs and their corresponding target genes. Results from this study will be reported.