Cloning And Functional Analysis Of Trans-acting Factor ABP3 Binding To Cis-acting Element ABRE Of Maize CatI Gene

Plant productivity is stongly influenced by abiotic stress contionsinduced by drought,high salt and low temperature ect..Though pople have paidattention to the research of abiotic stresses such as drought, high salt and lowtemperature for a long time, poor understanding of the mechanism governing stresstolerance of plant remained because of the complexity of enviromental stresses.Sofar,the effect of improving abiotic stresses tolerance in crops was not satisfied. Thedevelopment of molecular biology and biological technology offer new opportunitiesfor understanding plant and abiotic stresses deeply and improving abiotic stressestolerance in plants. Plants produced lots of reactive oxygen species(ROS)and formed oxidationstresses under drought,high salt and low temperature ect..ROS can react with a varietyof biomolecules,altering or blocking their biological funtions. It is very important toscavenge ROS in time .To minimize the toxic effects of ROS,plants evolved highlyregulated enzymatic and non-enymatic mechanisms to keep a balance between ROSproduction and destruction.The antioxidant enzyme catalase is very important amongthe enzymatic defense.CAT1 of plants was thought to play an important role in theenzymatic defenses,in response to enviromental as well as physiological stresses.Theexpression of antioxidant enzymes was induced weakly by plants itself,which was notenough to scavenge ROS rapidly.So,the studies on the transcription factors regulatingexpression of CAT1 are important. The major conclusions are as follows: 1,The full length of sequence of ABP3 was obtained by 5,RACE.The cDNAsequence of ABP3 contained 1465bp,and the open reading frame(ORF) was843bp,encoding 281 amino acids. The analysis of ABP3 amino acid sequencededuced in GenBank showed that the ABP3 belongs to bHLH (basic helix-loop-helix)transcription factor and the highest homology with the SPAT of Oryza sativa was39.1%;It also has higher homology with the hypothetical protein AT4g36930,bHLHprotein SPATULA and phytochrome interacting factor 3 (PIF3) of Arabidopsis. 2,ABP3 has DNA binding dimain and bound to ABRE specifically.ABP3transcription factor bound to the CACGTG of the core ABRE element. 3,ABP3 did not activate the expression of report gene in yeast cell.The possiblefunction is :1).This transcription factor only have DNA binding domain,no activatingdomain.2).It is a repressor,repressing the expression of report gene.3). It maybe cooperatewith other transcription factors to activate the expression of gene. 4,Using agrobacterium-mediated gene transformation by Vacuum-infiltration,wesuccessfully transfered the full length of sequence of ABP3 into Arabidopsis.By PCR,wehave obtained positive transgenic Arabidopsis seeds .The next mission is Screening seedson MS+Kan plate,then analyzing the physiological function. In summary,ABP3 transcription factors sepecifically bound to ABRE,but did notactivate the expression of report gene in yeast cell.we will research its physiologicalfunction in transgenic Arabidopsis,then offer the opportunity of using it for improvementof abiotic stresses tolerance of crops.