The Study On The Effect Of PAL Enzyme Activities And Gene Expression Pattern In Nitrogen Levels Of Eupatorium Odoratum

In recent years, biological invasion has become the world highly concerned hotspots. Those of alien species invasion have brought serious harm to the local farming,forestry, animal husbandry, fishery ecological environment. At present, more than380species of invasive plants were found in China, such as the Eupatorium odoratum.Eupatorium odoratum is a typical of the world recognized as perennial invasive weeds,originating in South America, and is now widely distributed in Hainan, Guangxi,Yunnan, Sichuan, Guizhou, and most regions of China, and have trend to spread to thenorth in China. Therefore, the emergency task is strengthening the study of the theory ofthe biological invasion and develops effective practical control technology.Phenylpropanoid pathway is one of the most important pathway of allelochemicals’synthesis in plants, and close related to the plant invasive, including the Eupatoriumodoratum and many other alien plants depend on specific allelochemicals’ to invade. Sostudy on the phenylpropanoid pathway conduces to reveal the mechanism of alieninvasion, and provide the effective measure on control alien invasion. In this study,select phenylalanine ammonialyase (PAL) enzyme, the key enzyme of phenylpropanoidpathway, as the target, and two ecotypes of Eupatorium odoratum, which origin fromMexico and invasion to Xishuangbanna, used as materials. Through studied on PALenzyme activity and gene expression of Eupatorium odoratum in different nitrogenlevel, in order to reveal the relationship of Eupatorium odoratum invasion withphenylpropanoid pathway in barren and fertile environment. The results in thefollowing:(1) Nitrogen levels have significant influence on height, chlorophyll content, andthe content of protein of the two ecotypes Xishuangbanna and Mexico. Contrast highnitrogen treatment with low nitrogen treatment, Xishuangbanna ecotype’s height,chlorophyll content, and the content of protein change more than Mexico ecotype’s.(2) PAL enzyme activity has significant influence by nitrogen level inXishuangbanna ecotype of Eupatorium odoratum. Compared with control, the highnitrogen treatment on the Xishuangbanna ecotype of Eupatorium odoratum, PALenzyme activity had increased in leaves and not significant change in stem; the low nitrogen treatment on the Xishuangbanna ecotype of Eupatorium odoratum, PALenzyme activity significantly influenced on leaves and stems, and change with time indirect ratio, namely PAL enzyme activity gradually strengthened with the Eupatoriumodoratum grown.(3) PAL enzyme activity has significant influence by nitrogen level in Mexicoecotype of Eupatorium odoratum. Compared with control, the high nitrogen treatmenton the Mexico ecotype of Eupatorium odoratum, PAL enzyme activity had decreased inleaves and increased in stems; the low nitrogen treatment on the Mexico ecotype ofEupatorium odoratum, PAL activity significantly influenced on leaves, and higher thancontrol in stems.(4) PAL enzyme activity in leaves of Xishuangbanna ecotype is higher thanMexico ecotype’s in high nitrogen and low nitrogen treatment. PAL enzyme activity instem of Xishuangbanna ecotype is less than Mexico ecotype’s in high nitrigen treatment.However, PAL enzyme activity in stem of Xishuangbanna ecotype is more than Mexicoecotype’s in low nitrigen treatment.(5) All treatment Eupatorium odoratum show that the PAL enzyme activity higherin stems than leaves. In the late stage of growth (after October2), that the PAL enzymeactivity is significant higher in low nitrogen treatment than high nitrogen treatment inXishuangbanna ecotype shows that phenylpropanoid pathway close related withinvasion in barren environment.(6)Using degenerate primer polymerase chain reaction (PCR),586bp gene segmentof PAL enzyme were cloning and sequencing. Sequencing result BLAST with NCBIdatabase, and further analyzed such as evolution tree, amino acid homology. Verify thissegment were from PAL gene of Eupatorium odoratum.(7) All kinds of materials show that the stem PAL gene expression than leaves’ byusing semi-quantitative PCR, and this result according to the enzyme activity result.However, PAL gene expression isn’t according to enzyme activity result in differentnitrogen levels treatment. This result shows that PAL enzyme activity is not related togene expression in different nitrogen level.In conclusion, in high nitrogen level, PAL enzyme activity in Xishuangbannaecotype is less than in Mexico ecotype’s; in high nitrogen level, PAL enzyme activity inXishuangbanna ecotype is more than Mexico ecotype’s. As mention before, we speculate that the PAL enzyme activity of Eupatorium odoratum increased significantlyand promoted allelochemicals produce to help invasion in barren environment. Theresults also show that PAL enzyme activity is not regulated by gene expression. Base onthis result, we can conclude that PAL enzyme activity was regulated at enzyme activitylevel and adapt to environment.