Abstract:

The hexameric Paf1 (RNA polymerase Ⅱ associated factor 1) complex is a crucial transcription regulator in eukaryotes.Paf1-regulated expression of specific genes in plants is closely related to diverse biological processes including growth,development,and stress responses.In order to get information on the responses of Paf1 to abiotic stresses in common wheat,homologous sequence searches were performed to identify all of the genes encoding each of the Paf1 subunits in the wheat genome.mCherry fusions of the wheat Paf1 subunit proteins were expressed in protoplasts and tobacco leaves for determination of protein subcellular localization by fluorescence microscopy.qRT-PCR assays were conducted to profile the expression of wheat Paf1 subunit genes in response to different abiotic stresses.The results showed that,in wheat,five of the Paf1 subunits,TaVIP3,TaVIP4,TaVIP5,TaVIP6,and TaPHP,were each encoded by one set of homeologous genes while the sixth subunit TaVIP2 was encoded by two sets.Plant VIP2 sequences had an N-terminal proline-rich region with variable length,and wheat TaVIP2 sequences had an additional glutamine-rich region.Protein subcellular localization assays revealed the nuclear localization of TaVIP2,TaVIP4,TaVIP5,and TaVIP6 proteins and the nuclear and cytoplasmic localization of TaVIP3 and TaPHP proteins.Gene expression analyses revealed similar tissue-dependent constitutive expression variations and similar stress-induced expression patterns of wheat Paf1 subunit genes.These genes coordinately responded to the stress of high temperature by expression upregulation and to the stresses of salt and drought by expression downregulation.Collectively,our results suggested the involvement of expression regulation of Paf1 subunit genes in the responses of wheat to abiotic stresses.

Key words: Wheat, Subunit of the Paf1 complex, Subcellular localization, Stress response