The Preliminary Study In The Function Of ChAOX2 Gene On Salt Resistance In Cerasus Humilis

Cerasus humilis,as a unique tree economic species in China,has a strong ability to resist stress.However,at present,the research on it is mainly focused on variety selection and cultivation,while the research on the physiological and molecular mechanism of its response to stress is rare.Alternative oxidase(AOX)is widely found in higher plants,some fungi and algae.It is the terminal oxidase of cyanide resistant respiration pathway in the electron transport respiratory chain on the inner membrane of plant mitochondria.When the cytochrome respiratory pathway is inhibited,AOX can alleviate the electron transport process in mitochondria,provide energy and maintain the urgently needed metabolic balance by directly reducing oxygen to water.AOX plays an important role in plant stress tolerance and is induced by a variety of metabolites and signals.Although significant progress has been made in AOX research,it is mainly concentrated in model organisms or herbaceous plants.As a cherry bush of Rosaceae,the study on AOX of C.humilis is empty.In order to further enrich the gene resources of AOX in forest trees,we cloned AOX2 gene,ChAOX2,from "Nongda No.6",to explore its function responsed to salt stress.The results are as follows:1.The gene of ChAOX2 was cloned from the leaves of C.humilis.The expression vector pGWB5-ChAOX2 was obtained by connecting ChAOX2 with pGWB5 plasmid by gene engineering and successfully introduced into Agrobacterium.2.The subcellular localization of tobacco showed that ChAOX2 was located in mitochondria.Compared with the phenotypes of ChAOX2 overexpressing lines,WT and mutant(aox)plants,it was found that during normal conditions,the phenotype of aox was significantly different in plant type,plant height,flowering time,bolting time,seed pod size and hypocotyl length,which indicated that the growth and development of the plant were significantly affected by ChAOX2.3.There was a significant difference in the amount of expression of ChAOX2 in the tissues of over expressed Arabidopsis plants,and the expression of ChAOX2 in roots and stems was the least and the most,respectively.The expression of ChAOX2 in various tissues changed significantly under salt stress indicated that ChAOX2 responds to salt stress.4.Salt stress on ChAOX2 overexpressing plants OE1,OE2 and WT,aox showed that ChAOX2 can improve the salt tolerance ofArabidopsis plants,while aox plants have increased salt sensitivity.Measurements of various physiological indicators show that overexpression of ChAOX2 can enhance plant respiration,reduce ion leakage,increase proline content,reduce ROS accumulation and increase antioxidant enzy me activity.DAB and NBT staining further confirmed the changes of the above physiological indicators.In conclusion,the indexes of phenotypic,physiological and molecular indicate that ChAOX2 responds to salt stress and plays an important role in the network system of plants responding to salt stress.