| Plant productivity is strongly influenced by abiotic stress conditions induced by drought, high salt and low temperature etc.. Though people have paid attention to the research of abiotic stresses such as drought, high salt and low temperature for a long tune, poor understanding of the mechanism governing stress tolerance of plant remained because of the complexity of environmental stresses. So far, the effect of improving abiotic stresses tolerance in crops was not satisfied. The developments of molecular biology and biological technology offer new opportunities for understanding plant and abiotic stresses deeply and improving abiotic stresses tolerance hi plants.Plants produced lots of reactive oxygen species (ROS) and formed oxidation stresses under drought, high salt and low temperature etc.. ROS can react with a variety of biomolecules, altering or blocking their biological functions. It is very important to scavenge ROS hi time. To minimize the toxic effects of ROS, plants evolved highly regulated enzymatic and non-enzymatic mechanisms to keep a balance between ROS production and destruction. The antioxidant enzyme catalase is very important Among the enzymatic defenses. CAT1 of plants was thought to play an important role in antioxidant defenses, hi response to environmental as well as physiological stresses. The expression of antioxidant enzymes was induced weakly by plants itself, which was not enough to scavenge ROS rapidly. So, the studies on the transcription factors regulating expression ofCATl are important, hi this context, the cloning and functional analysis of trans-factors binding to cis-element ABRE2 of CAT1 gene in maize will be presented.The major conclusions are as follows:1. 17dpp, 21dpp (17, 21 days post-pollination) cDNA libraries of maize embryo, containing 5.2 X 106 cfu and 3.34 X 106 cfu, respectively were constructed. The recombination rates were 85%. The size of inserts was over 1kb.2. The two libraries were screened by yeast one-hybrid system. Seven positive clones were named as ABPs (ABRE binding proteins). They were ABP2, ABP3, ABP4,ABPS, ABP6, ABP7 and ABP9. The results of sequence analysis showed that ABP2, ABP4, ABP6 and ABP9 belonged to bZIP transcription factor and ABPS, ABPS, ABP7 belonged to bHLH transcription factor. Seven ABPs mentioned above specifically bound to ABRE in yeast cells.3. The analysis of ABPs protein sequences deduced in GenBank showed that the highest homology between ABP2 and ABF3 of Arabidopsis was 34.1%; between ABP3 and SPAT of Oryza sativa was 36.9%; between ABP4 and TRAB1 of Oryza saliva was 44.3%; between ABPS and MYC protein of Arabidopsis was 19%; between ABP6 and ABI of Arabidopsis was 54.6%; between ABP7 and DBP of Oryza sativa was 26.6%; between ABP9 and ABI of Arabidopsis was 41.9%.4. The expression of ABPs was induced by various abiotic stresses such as drought, high salt, low temperature, ABA, and H2O2. High salt induced expression ofABP2, ABP3, ABPS, ABP6 and ABP9 and inhibited that of ABP4 and ABP7. Drought induced expression of ABP2, ABP3, ABPS, ABP6 and ABP9 except for ABP4 and ABP7. H2O2 induced expression of ABP2, ABPS, ABPS, ABP6 and ABP9 and inhibited that ofABP4 mdABP7. ABA induced expression ofABP2, ABPS, ABPS, ABP6, ABP7 and ABP9 except for ABP4. Low temperature did not induce the expression of ABPs. So, ABP2, ABP3, ABPS, ABP6, ABP7 and ABP9 were likely to be the CBF1, which interacted with cw-element ABRE2 of Catl gene. ABP4 were likely to be the CBF2, which interacted with m-element ABRE2 of Catl gene. The above results offered new data for the signal transduction of Catl expression.5. The full length of sequences ofABP2, ABP4 and ABP9 was obtained by 5'RACE. The cDNA sequence ofABP2 contained 1450bp and the open reading frame was 1056bp, encoding 351 amino acid. Compared ABP2 with ABF3 of Arabidopsis, the homology was only 33.6%. The cDNA sequence of ABP4 contained 1835bp and the open reading frame was 1083bp, encoding 360 amino acid. Compared ABP4 with TRAB1 of Oryza sativa, the homology wa...
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