[Objective] This study was conducted to clarify the biological information of PHYB genes in upland cotton （Gossypium hirsutum）. [Method] Two PHYB genes were identified from the genome database of allotetraploid cotton （G. hirsutum L. acc. TM-1）, and were found to be distributed on subgenomes A10 and D10. And then bioinformatic analysis on these two genes were performed. [Result] The PHYB genes of upland cotton had the same motifs and domains with the PHYB genes in other plant species, and even the number and location of the motifs and domains of these PHYB genes were consistent. The PHYB amino acid sequence alignment and the phylogenetic tree constructed based on PHYB amino acid sequence of these plant species indicated that the two PHYB genes in upland cotton had higher homology and closer evolutionary relationships with cocoa （Theobroma cacao）, but lower similarity to PHYB genes in monocotyledonous plants, such as rice （Oryza saitva） and corn （Zea mays）. The comparison of PHYB gene structure also revealed that plant PHYB gene was more conserved during evolution. The autophosphorylation of dozens of phosphorylation sites in upland cotton PHYB gene may be essential for the functions of phytochromes and plays a significant role in regulating phytochrome-mediated signal transduction pathways. [Conclusion] The results of this paper will provide a theoretical basis for the cloning and functional research of PHYB genes.
