The Study On The Plant's Defense Response Induced By HarpinEccs Protein

HarpinEccs protein in the study was expressed by hrpNCSDS001 gene,exsited in Erwinia carotovora subsp. carotovora strain CSDS001, which was induced by Isopropyl-β-D-Thiogalactoside(IPTG) in E. coli strain JM109. This article mainly focus on the research and argument on the plant defense response induced by HarpinEccs from biological activity, biological effect,physiological biochemical level and molecular level.Adopting injection method to detect the hypersensitive reaction(HR) of non-host plants induced by HarpinEccs and its biological activity, it turned out as below: 300μg/mL HarpinEccs could obviously induce the tobacco's hypersensitive reaction, around 24 hours, hypersusceptibility spot could be seen by eyes, and induced non-host plants such as cockscomb and Chinese flowering apple with HR, which further demonstrated that HarpinEccs possess certain biological activity.The indoor pharmacodynamic test–using HarpinEccs of different concentra -tion to prevent and cure tobacco mosaic virus (TMV) showed that HarpinEccs is able to induce tobacco with an obvious resistance,and in particular, the most distinct effect came out with the concentration of 30μg/mL ,with a relative control-efficiency of 65.84%;what's more,the inducement resistence effect onTMV lasted more than 30 days. The experimental results revealed that to apply HarpinEccs is an effective method to induce tobacco's resistance against TMV and control the plant disease. After treating the tobacco with HarpinEccs(30μg/mL)and measuring the activity change of some defense-related enzymes, it turned out that there were different enhancement of phenylalanine ammonialyase (PAL), polyphenoloxidase (PPO) and peroxidase (POD);During 24,24,48hours after the treating,the activity of three enzymes reached the peak level,with a individual rise of 50%,132% and 90.3% compared to water, in addition,the extent was similar to or beyond the processing by salicylic acid(SA).Using Arabidopsis thaliana gene chip to analyze the change of Arabidopsis thaliana gene expression map induced by HarpinEccs from transcriptional level. According to the comparative analysis of Arabidopsis thaliana gene expression which induced by HarpinEccs and HarpinEa's in 24hours, it showed that HarpinEccs has a more remarkable function on inducing the gene expression of Arabidopsis thaliana, with a reference to HarpinEa . According to the analysis of HarpinEccs inducement results in different treating time, it showed that with the extension of treating time(3h-48h), there was a gradual rise of gene expression differential numbers. It went to the maximum at the 24th hour, then went down slowly to tend to be steady at the 48th hour, maintaining the number on a higher level. The difference indicated that the systematic acquired resistance induced by HarpinEccs is a time series process. Treeview Cluster analysis and lignin synthetic route analysis showed that during different processing time of HarpinEccs, gene expressions related with lignin synthetic route were partly up-regulated, while some were down-regulated, with a particular up-regulation of AT5G04230 and AT3G28200 gene expressions, and the gene expressions of key enzyme of lignin synthesis, which came to a conclusion that HarpinEccs is closely connected with the synthesis of lignin. The analysis on 5 sorts of pathogenesis-related protein genes showed that there were expression differences during the process of HarpinEccs, especially there was a notable up-regulation of AT2G14610 and AT1G75040 expressions. Based on the results above, there is a prediction that HarpinEccs is able to induce the signal passway of different defense actions and related-gene expressions of Arabidopsis thaliana, which acquired the plants of disease resistance.