Study On Plant Phenolic Compound Content And Their Response To Hyperarid Extreme Environment

Plant polyphenols is an important group of secondary metabolites. As a defense material at molecule level, it has significant ecological importance.Plants could respond to stress usually by means of morphological changes, physiological response, genetic diversity and secondary metabolites. There have been many studies on morphological changes, physiological response and Genetic diversity, however, research on the secondary metabolites is a weak point. The purpose of the present study was to disclose the use of secondary metabolites. Through the investigation on phenolics compounds in plants, this paper mainly studied the content of phenolics compounds in plants and their responses to hyperarid environments stress.The thesis profoundly explored extraction and quantitative analysis of phenolics compounds, distribution and change of phenolics compounds in plants, molecular constitution of tannins in Tamarix ramosissima and the relationship between soil moisture and phenolic compounds.The studies come to at least four important results: 1. There were more total polyphenols and flavanoids in bark than in leaves, and the content were the least in branch. 2. There were more total polyphenols and flavanoids in April than in July in Tamarix ramosissima, Populus euphratical and Phragmites australis, While in Caragana there were more total polyphenols and flavanoids in April than in July. 3. Flavanoids with the structure of orho-diphenol-hydroxyl were detected in Tamarix ramosissima; condensed tannins and hydrolysable tannin were both founded, the basic structural unit of Chinese Tamarisk is procyanidin which cis-isomer was more than 70% .This structure will be helpful for oxidation resistance. 4. The total phenolic compounds content was negatively related to the soil moisture; The tannin content was negatively related to the soil moisture; A markedly positive linear correlation between the condensed tannin content and the soil moisture could be observed.These means when the soil moisture reduced ,the content of total phenols and tannin would increased , this would reduce cells' water potential which could prevent water running off;at the same time ,phenols could compound with sugar which would strengthen the elastic behavior and viscous property,these could prove cell from mechanical damage. And we advanced that the hydrolysable tannin content should be negatively related to the soil moisture. Water would be released as hydrolysable tannin formed, and it also was favorable for the drought-resistanc of plants.The innovations for this paper are as follows: 1.The result shows that the total phenolic compounds content was negatively related to the soil water content. 2. We advanced that the hydrolysable tannin content should be negatively related to the soil moisture. Water would be released as hydrolysable tannin formed, and it also was favorable for the drought-resistanc of plants.All these opinions will bring forth profound influence not only on the investigation on phenolics compounds but also on the restoration ecology and whole plant stress resistance research field.