| China has become one of largest area, suffering from acid rain,follow by Europe and America. By some estimates acid rain falls on a third of all agricultural land. It can hurt the economy,break the ecological balance around the world, Therefore, the mechanism how plants respond to acid rain stress and how Acid rain(AR) affects plant growth drew more and more people’s attention. One of these studies is that acid rain and biotic stress combination has made large number of Cryptomeria grow poorly or dead[1]. This also makes this experiment more significant. In this paper,we used the model plant as the experimental materials to explore weather acid rain can change the disease resistance of Arabidopsis thaliana.Now, the major results are shown as follows:(1) Statistic foliar growth area of Arabidopsis thaliana after simulated acid rain treatment.We found that the simulated acid rain can make the leaf area growth rate decreased. At the same time there is significant different between Arabidopsis 3 days after the treatment of simulated acid rain and the control group.(2)We has determined the relative content Malondialdehyde malonic dialdehyde(MDA) and three kinds of activities of antioxidant enzymes, the results showed the 3 day of the simulated acid rain treatment makes the Arabidopsis MDA relative content increased and Peroxidase(POD), Ascorbate Peroxidase(APX) activity increased. This shows that the 3 days of the treatment of simulated acid rain made lipid damaged on Arabidopsis thaliana, and the increasing of the activity of POD, APX is accelerating scavenge reactive oxygen species. The two experiment shows that 3 days is a suitable time, which is enough to cause the change of physiological phenotypes in Arabidopsis thaliana.(3) Injection of Pseudomonas syringae pv. maculicola ES4326(Psm ES4326),of Arabidopsis was diluted coated and colony count. The results showed that the 3 day of the simulated acid rain treatment can make the number of pathogens of Arabidopsis decreased about 2-5 times, while salicylic acid treatment can make the number of pathogens of Arabidopsis decreased about 10 times. Combined with the research of Lee, we hypothesized that the expression amount of simulated acid rain can change the salicylic acid signaling pathway in Arabidopsis genes, the plants showed stronger tolerance to pathogen.(4) On the expression of quantity of simulated acid rain before and after treatment and after inoculation of Arabidopsis related genes were determined by fluorescence quantitative PCR technique. The results showed that: the treatment of simulated acid rain, the downstream genes Salicylic acid(SA) and Jasmine acid(JA) signal pathway on the dramatic rise, the upstream genes up-regulated greatly; and the inoculated before 12 h, PR1 gene transcription level in experimental group had significantly higher than control group, which should be caused by simulated acid rain treatment of Arabidopsis direct cause more disease resistant.(5) Growth of virulent in Arabidopsis thaliana leaves exposed to water or SiAR for 3 days. Leaves of Col-0 npr1 and NahG plants were inoculated with either the virulent Psm 4326.The result shows that is: there is no significant difference between the experimental group NahG, npr1 and their control groups, And there is significant difference with of Col-0 of the experimental group and control group. This indicates that the simulated acid rain may regulate the PR1 gene via SA signaling pathway to enhance disease resistance in Arabidopsis thaliana.The results of bacterial pathogen counts proved that the simulated acid rain can enhance the resistance of Arabidopsis thaliana. The quantitative PCR experiment confirmed that the effect of simulated acid rain on the resistance of Arabidopsis thaliana was the expression of PR1 gene. NahG and npr1 bacterial pathogen count experiments showed that simulated acid rain by changing the content of SA to regulate the expression of PR1 gene, and thus enhanced the resistance of Arabidopsis. |
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