Effect Of AtHARBI1-2 Over-expression On Growth And Development Of The Transgenic Arabidopsis Thaliana

The Harbinger Transposase Derived 1?HARBI1?protein was derived from the active Harbinger transposase in the common ancestor of the vertebrate?Teliosaurus?about 450 million years ago.HARBI1 is the only known homologous gene with PIF/Harbinger transposable element in vertebrate,encoding 350 amino acids.HARBI1 is a DDE transposase,belonging to the DDE_Tnp₄ family of proteins,whose molecular structure is characterized by three highly conserved nucleophilic amino acid residues,including two aspartic acid residues?D?and one glutamic acid residue?E?.HARBI1 contains the common characteristics of DDE transposase,which is a key protein that catalyzes DNA break and recombination.This experiment is based on the study of CiHARBI1 gene in Caragana intermedia,in order to verify and study the function and mechanism of HARBI1 in plants.In this experiment,the homologous gene AtHARBI1-2 in Arabidopsis thaliana was selected for functional analysis.The main results are as follows:1.AtHARBI1-2,an DDE_Tnpp₄ family gene,was cloned from Arabidopsis.The cDNA length of AtHARBI1-2 gene is 1,509bp,encoding 502 amino acids,and the molecular weight of the protein is predicted to be 56.82 kD.The results of amino acid sequence alignment and phylogenetic analysis showed that the homology was 70%between AtHARBI1-2 and CiHARBI1.2.AtHARBI1-2 was induced by cold stress at 4? and the expression level was up-regulated.3.The cotyledon of the AtHARBI1-2 overexpressed lines curled downward at the seedling stage.The highly overexpressed line grew and developed slowly,the rosette of the plant was smaller than that of the wild type,and the leaf was curl.The bolting time of the transgenic line was later than that of the wild type.4.The content of various cytokinins in the 7-day seedlings of AtHARBI1-2 overexpressed line was significantly higher than that of the wild type,and the content of ME-IAA was significantly lower than those of the wild type,while the content of IAA was significantly higher than those of the wild type.The above results indicated that AtHARBI1-2 might affect the content of IAAs and cytokinins of the transgenic Arabidopsis via a currently unknown pathway,and resulted in abnormal cotyledon and leaf development in transgenic lines.However,the phenotype was not completely consistent with that of the CiHARBIl or AtHARBI1-1overexpression lines,a sign of partially function redundancy among the 3 genes.