Influence On Physiological And Biochemical Characteristics Of Mango Under Drought Stress And Mango MiASR Gene Cloning And Expression Analysis

All Plants have the ability of endurance and resistance to environmental stresses. Drought, low temperature, high temperature and high salt stress can cause plant transfer specific and complex control system against stress and maintain normal metabolism of plant itself. Plants have many stress resistance genes to involve in stress control and a lot of stress resistance genes has also been separation, cloning, applied in plants to breed improvement. Some of these genes are induced by ABA signal to express and synthetise a series of functional proteins to protect plant cells. ASR protein of these functional protein has beened widely concerned. Many studies show that ASR protein (abscisic acid, stress, mature induced proteins) has an important regulatory role in abiotic stress, the different stages of fruit development, fruit ripe and so on. Gene expression pattern analysis showed that ASR gene was induced to express by chilling injury, drought, abscisic acid treatment, salt and so on, and some studys showed that ASR gene was also induced in the process of the maturity of fruit. This experiment determines and analyzes the change rule of physiological and biochemical indexes of mango under drought condition. At the same time, the experiment also clones the cDNA full-length sequence of mango MiASR gene, analysises bioinformatics and constructs Eukaryotic expression vector. In addition, this research also analyzes expression pattern of MiASR in different organizations, different development period of mango fruit, abiotic stress and fruit postharvest. The main results are as follows: 1.Compared Tainong No.1with Siji mango by leaf water content, relative conductivity, mda content, superoxide dismutase (sod) activity under drought stress, the result found that Tainong No.1have stronger tolerance ability to water stress than siji mango. But the result indicated that chlorophyll content and proline content cannot serve as the evaluation index of drought-resistant ability mango cultivars due to the insignificant difference of two indicators.2. By RT-PCR and improved5RACE method the full-length of cDNA of MiASR gene was cloned.This gene included an open reading frame of516bp,5untranslation section of70bp and3untranslation section of241bp. And the ORF translates172amino acids. This gene has an ABA/WDS sequence tags. The molecular weight of MiASR protein is19299.7.The isoelectric point is5.84.This protein has seven function domain structures,and there is obvious hydrophilic/hydrophobic regions.3. By means of expression analysis of MiASR in different tissues and organs, and fruit of different development period of mangifera indica, the study indicated the expression of this gene raised obviously in the more mature tissues and organs, such as old stems, old leaves, mango fruit before and after the harvest time. At the same time, MiASR gene also has higher expression in mango flowers, and it may be connected with the flower.4. Under abiotic stress treatment, low temperature inhibited expression of MiASR gene, and when72h after being treated the gene had higher expression level in stem. Under high salt and PEG-simulated drought conditions, expression of MiASR gene was lowered first, raised and lowered finally. It showed that expression of the gene in stems and leaves at different times after being treated had a peak. It indicated that low temperature could inhibit expression of MiASR gene in leaf, and other adversity stress could increase expression of MiASR gene in mango stem and leaf to a varying degree, and there were obvious differences between stem and leaf. MiASR genes had a certain relationship under stress response with plants in low temperature, high salt, drought.5. Under drought stress condition, expression analysis of MiASR gene in two mango cultivars indicated that MiASR gene in plants under water stress condition had been involved in adjusting plants adversity. As the aggravate of drought stress, expression of MiASR gene increased all the time, and if stress was relieved or eliminated, expression quantity of the gene would reduce. So MiASR gene may be closely related to stress response of plant in drought stress. And MiASR protein may be one of the key regulatory factors with drought stress reaction, so as to balance expression of other adversity proteins. And MiASR gene may also be an important protein to protect plants directly respond to adversity stress to maintain normal life activities.6. Before and after mango harvest—the skin color turn early MiASR gene was with high expression,then continued to decline. Compared with the control, heat shock, citric acid, oxalic acid and heat shock with1-MCP treatment inhibit expression of MiASR gene.Presumably the gene has certain inner link with the senescence of fruit and may delay the fruit senescence.7.Build expression vector by using eukaryotic expression vector pBI121-gus and import agrobacterium. In order to further study of function of MiASR gene,the arabidopsis flowering soaking method for genetic transformation was used. But after doing many experiemnts, the transgenic plants didn’t have been obtained. Specific operation approach that flowering soaking method that is used to turn arabidopsis thaliana may still need to be more optimized and explored carefully.