Cloning And Function Analysis Of LoCAT Gene From Larix Olgensis

Subjected to abiotic stresses,ROS of plants is substantially accumulated,thereby leading to severe damage to cellular components,e.g.membrane and DNA.Abiotic stresses severely affect distribution,growth,development and quality formation of plants.Catalase(CAT),belonging to hemoglobin enzymes mainly catalyze the conversion of H2O2 to H2O and O2 in plants.Over-expression of CAT can improve oxidative stress tolerance by efficiently scavenging ROS produced in plants.A CAT(LoCAT)was cloned from Larix olgensis,the protein encoded by the gene was analyzed by bioinformatics,and the expression pattern of the gene under abiotic stress was analyzed by real-time quantitative.In addition,plant expression vector of LoCAT were constructed and transformed into tobacco and Larix olgensis.Physiological indexes of transgenic plants were analyzed under drought and salt stress.The main results were as follows:(1)A CAT was cloned based on specific primers designed according to the CAT sequences from transcriptome database of Larix olgensis.The results show that the complete length of open read frame(ORF)is 954bp,encoding 317 amino acids.The results of phylogenetic tree analysis indicated that there was a close relationship between Larix olgensis and Picea sitchensis.(2)Real-time quantitative polymerase chain reaction analysis revealed that CAT is highly expressed in leaf,while less expressed in stems.The expression of LoCAT was significantly enhanced by salt and drought stress.(3)Gene was transformed into pBI121,and introduced into tobacco by Agrobacterium tumefaciens-mediated transformation.The transgenic tobacco plants and the wild-type plants were treated with drought and saline.The physiological indexes measurement showed that the enzyme activities of CAT,SOD or POD in the transgenes were higher than that of the wild type.On the contrary,the contents of MDA in the transgenes were lower than that of the wild type.Therefore,over-expression of LoCAT in transgenic tobacco plants substantially enhanced the tolerance to drought and salt stresses.(4)When gene was transformated into Larix olgensis by Agrobacterium tumefaciens-mediated transformation,expression of LoCAT improve the oxidation resistance of transgenic embryogenic callus.