Salicylic Acid Induced The Shoot Of Arabidopsis Physiological Mechanism Of Arsenic Resistance

With the development of industrial, agricultural and continuous application of chemicals that containing arsenic, arsenic contamination has been a worldwide serious problem. Arsenic contamination of soil, air and water is a threat to crop production and human health. Therefore, the research on the plants physiology which exposed to the arsenic environment can provide a good data support for a further study on the response mechanism of plants under stress.Salicylic acid is a small molecule phenolic substances in plant which was confirmed a hormone member family in 1992. At present, SA was applied to the study of plant disease resistance has gradually become a hot spot research. It is evidenced that SA does not only adjust the process of the plant's growth and development, but also induce a plant resistance, resist to the damage caused by adverse factors.The model plant of molecular biology Arabidopsis was used, the plant physiological indicators were studied when the wild type and the mutant were under arsenic stress.1. Investigation of Analysis Methods of Salicylic Acid in Plant TissueIn plants, SA mainly in the form of free and bound. The bound SA is an inactive form of SA-2-O-β-glucoside (SAG) which contains the free SA and the glucoside. Under certain circumstances, SAG is released into the cell gap which can converted to free SA, the free SA enters the cell, induce the defense responses. Therefore an accurate determination of SA in plant tissue is a necessary precondition to intensively study its important function and the mechanism of disease resistance.Salicylic acid (SA) in plant tissue was analyzed by high performance liquid chromatography (HPLC) in this experiment, the different results were obtained by using the ultraviolet and the fluorescence detectors. By comparison, the later one was more sensitivity, fifteen times higher than the former one. The liquid chromatography conditions were also investigated, the results indicated that when pH 5.5 sodium acetate: methanol (9:1,V/V) was the mobile phase, the separation of SA from the complex mixtures was better than others. Use this method, the relative standard deviation (RSD) of the precision was 1.73%, the repeatability and the stability were also good (the RSD of the stability was 4.6%). Two kinds of Arabidopsis thaliana (Wild type and the mutant of salicylic acid) were used to test the method. SA in this two kinds of plants were extracted and analyzed by our method, the total SA content in wide type is nine times as much as in sid2 which is coincided with the reported literatures.2. Salicylic acid induced the shoot of Arabidopsis physiological mechanism of arsenic resistanceSelected two samples of Arabidopsis plants: wild type and sid2 for arsenic treatment, the concentration is 0,75,150,300μM arsenic, we found that:1)there was no significant difference between WT and sid2 biomass,2) under normal conditions, the total SA content in wide type is nine times as much as in sid2,3) dealt with the same concentration of arsenic, the shoot of WT accumulate more arsenic than sid2,4)under arsenic circumstance, the content of SA in the shoot of WT was increased with the time extending and the increased concentration of arsenic; because of the deletion gene which used for synthesis of SA, the pathway leading to the salicylic acid biosynthesis was impaired, there was no significant difference between the content of SA and the time extending and increased arsenic concentration,5) under arsenic exposure , the in vivo hydrogen peroxide content in two plant species was increased, that is arsenic can produce oxidative stress in the shoot of plant tissue,6) the antioxidant system in WT and sid2 was different , in WT, SOD was increased, CAT was no significant changed, POD was increased; in sid2, SOD,POD,CAT were all lowed.In brief, this paper studied the determination of salicylic acid which as the hormone in plant tissue and the changes of the plant physiological indicators of the model plant Arabidopsis thaliana under the arsenic stress which can provide an effective data support on study of salicylic acid in plant resistance, and also take a preparation for the mechanism of salicylic acid disease resistance.