Cloning,Expression Analysis And Functional Verification Of Phytochrome Genes In Common Wheat (Triticum Aestivum)

As one of the environmental elements,light plays important roles on plant vegetative growth and reproductive development.Through a series of biochemical reactions,light lead to corresponding biological activities,such as opening and closing of stomata,photorespiration,chloroplast movement,photosynthesis,photomorphogenesis,and biological clock.As a kind of light receptors in plant,phytochromes perceive the quality,intensity and the cyclical changes of light,then influence the growth and development of plants.Signal pathway mediated by phytochromes has been extensively researched in model plant Arabidopsis thaliana,but little is known in crops.Arabidopsis phytochrome A is the major receptor of far-red light,which facilitates the inhibition of hypocotyl elongation,opening of the apical hook,expansion of cotyledons,accumulation of anthocyanin and FR preconditioned blocking of greening under continuous FR(FRc)light.We cloned three copies of phytochrome A,named TaPHYA1?TaPHYA2 and TaPHYA3,from common wheat(Triticum aestivum).We analyzed their structures of genomic sequences and the predicted amino acid,and their expression patterns of mRNA abundances in seedlings in response to different light conditions,including light quality,dark-to-light transitions,long-day and short-day conditions.In addition,we studied their functions by the phenotypes of overexpression of TaPHYAs in Arabidopsis.Results as following:1.Wheat contains three copies of phytochrome A genes,TaPHYA1,TaPHYA2 and Ta PHYA3 in its A,B and D sub-genome,respectively.2.The phytochrome A genes from wheat have very similar genetic structure.The position and the length of exons and introns of TaPHYA1 and TaPHYA3 are identical.The first exon and intron of TaPHYA2 are the same with that of TaPHYA1 and TaPHYA3 in spite of the single nucleotide polymorphism of TaPHYA2 lead to its early termination.3.Both TaphyA1 and TaphyA2 have GAF domain,PAS domain and HisKA domain,While TaphyA2 only have GAF domain and PAS domain because of an early termination in the process of protein translation.4.Under different conditions,the transcription patterns of TaPHYA1 and TaPHYA2 are identical,but differs with that of TaPHYA3 under the same conditions.The expression levels of TaPHYA3 are much higher than that of TaPHYA1 and TaPHYA2 under the same light treatments.5.The transcription abundances of TaPHYAs in wheat spikes is higher than those in roots,leaves and leaf-sheathes.The transcription abundance of TaPHYA3 is lower than that of TaPHYA1 and TaPHYA2 in spikes,but higher than that of Ta PHYA1 and TaPHYA2 in roots,leaves and leaf-sheathes.6.The preliminary study in transgenic Arabidopsis lines of TaPHYA1 shows that Ta PHYA1 fail to complement phenotype of phyA-211 mutant under continuous far-red light(FRc),but TaPHYA1 can inhibit Arabidopsis hypocotyl elongation of transgenic lines under continuous red light,continuous blue light and continuous white light with short hypotycol in the phyA-211 mutant background.