Cloning And Functional Analysis Of PsnHB22 Gene In Populus Simonii × P.nigra

HD-Zip transcription factor is a large family of plant-specific proteins containing homology domain(HD)and leucine zipper(LZ)motifs.It is a type of transcription factor related to growth and development,unique to higher plants.It plays an important role in life activities such as light signal transduction,abiotic stress and organ development.In this paper,the PsnHB22 gene was cloned from Populus simonii ×P.nigra,and the bio informatics analysis were carried out.The interaction between PsnHB22 protein and PsnCYCD1;1 protein and the biological characteristics of PsnHB22 transgenic tobacco were studied.The main results are as follows:(1)The PsnHB22 gene CDS sequence of Populus simonii × P.nigra has a total length of 549 bp and encodes a protein sequence consisting of 182 amino acid residues.The protein is an unstable hydrophilic protein without signal peptide and transmembrane helix,and there are ZF-HD-dimer domain and homeo-ZF-HD domain in the nucleotide region;analysis of the phylogenetic tree revealed that the PsnHB22 protein has higher homology with Populus trichocarpa and Salix brachista.(2)Construction of pGBKT7-PsnHB22 yeast expression vector.The experiments prove that the PsnHB22 protein has no self-activation activity and no toxic effect on the Y2IIgold strain;through yeast two-hybrid experiment it is proved that the PsnHB22 protein interacts with the PsnCYCD1;1 protein.It is speculated that the PsnHB22 gene may participate in the process of PsnCYCD1;1 gene regulating plant cell division and growth.(3)Construction of pROK?-PsnHB22 plant overexpression vector,Agrobacterium-mediated genetic transformation of tobacco,PCR test results showed that PsnHB22 gene has been integrated into the tobacco genome.The height of the transgenic tobacco plant is significantly lower than that of the wild type;and some transgenic tobacco plants have narrow leaves,significantly different leaf widths than the wild type,and the leaf epidermal cells become smaller;which is speculated that the PsnHB22 gene may play an important role in the process of plant height growth and leaf morphogenesis.(4)The chlorophyll content of the leaves of the same parts of transgenic tobacco and wild-type tobacco was determined.The results showed that the chlorophyll content of transgenic tobacco was significantly higher than that of wild-type tobacco.It is speculated that the PsnHB22 gene may be involved in the process of photosynthesis.