Genome-wide profiling of developmental, hormonal or environmental responsiveness of the nucleocytoplasmic transport receptors in Arabidopsis

Being poilkilothermic and sessile organisms, plants have to respond quickly to changing environmental cues, and a higher order of gene regulation is required The significance of nucleocytoplasmic transport via importin alpha and importin beta (alpha/beta) has been exhibited in a wide spectrum of biological processes However, most of these receptors have not been characterized as to which cellular or development processes are required and how their expression is regulated by environmental stimuli Here we pursued a phylogenetic analysis and investigated the expression patterns of all 8 IMP alpha s and 18 IMP beta s in Arabidopsis The IMP alpha isoforms could be tracked back to a common ancestor, while the IMP beta s derived from different ones The majority of transport receptor genes were constitutively expressed Intriguingly, AtIMP alpha 5, 7, 8 and AtIMP beta 5 were specifically expressed in different tissues AtIMP beta 3 was the sole receptor that was obviously modulated by exogenous phytohormones, whereas three IMP alpha s and five IMP beta s exhibited responses to environmental stimuli Furthermore, our RT-PCR data provided direct evidence that AtIMP alpha 5, 8 and AtIMP beta 5 are not pseudogenes and we also corrected the open reading frame annotation of AtIMP alpha 8 These genome-wide profilin g results not only widen our understanding of these transport receptors, but also provide strong evidence supporting the role of transport receptors in multiple signaling pathways and give us an insight into the further analysis of nucleocytoplasmic trafficking in Arabidopsis (C) 2009 Elsevier B V All rights reserved