Study On Responses Of Several Woody Plants To Stimulated Acid Rain Under Different Calcium Conditions

As one of the world's top ten environmental issues,acid rains have attracted more and more attentions of society and scholars.Acid rains could deplete the calcium from the plants or ecosystems,lead to serious negative effects on plant growth,and thus cause the decay of forests.The application of exogenous calcium have previously been reported to aid in the recovery of forest that was damaged by acid rains,however,few studies have been performed to compare the resistance to acid rain under different calcium concentrations.On the other hand,many researchers have devoted their attentions to impacts of acid rains on physiology but not on mechanism levels.Base on the above significances of acid rain effects,this thesis was designed to investigate the effects of acid rains on plant seeds and seedlings of Pinus massoniana,Cryptomeria fortune,Cunninghamia lanceolata,Liquidambar formosana,Pinus armandi and Fagaceae henryi at three calcium concentrations levels.And also,difference gel electrophoresis(DIGE) technology was used to determine the variations of the proteomics in Pinus massoniana and Pinus elliotii under acid rains stress.The main results are as follows:The vigor index,seed germination rate,germination index and radicle length of the six kinds of plant seeds were significantly inhibited by pH 3.0 acid rain treatment.; Calcium play an important role in seed germination with higher germination ability at higher calcium condition,indicating the alleviation of the acid rain induced damage on seed.There was an inter-specific difference of the restoration extent since the plants have different needs for calcium.Different damages of acid rains on the leaf necrosis,chlorophyll content and net photosynthetic rate of the six plants were observed at different calcium concentrations;and the seedling was more resistant to acid rains stress at higher calcium concentration.As an increase of calcium concentration,damage-areas caused by acid rains on leaves reduced or even disappeared and chlorophyll content and photosynthetic capacity increased.After 2 months treated by pH 3.0 acid rains,35 proteins expression with at least a 2-fold changed were observed in seedling of Pinus massoniana,therein 14 proteins being down-regulated and 21 proteins being up-regulated.Due to the acid rains stress, there were 3 down-regulated proteins belonging to Rubisico large subunits;and caused the reduction of the plant photosynthesis.At the same time,several energy metabolism-related proteins were also detected to be down-regulated,such as sucrose-phosphatase,pyruvate dehydrogenase,glyceraldehyde-phosphate dehydrogenase,phosphoribulokinase,fructose-bisphosphate aldolase,Quinone oxidoreductase,which are key enzyme of glycolysis,pentose phosphate and fatty acid metabolism pathway.The above results indicate acid rain can influence the activity of protease and further influence plant's physiological processes.Acid rain also lead to other energy-related protein expression increased.Such as ATP synthase,granule-bound starch synthase,malate dehydrogenase et al.It means plant rely on more energy supply by other energy pathway in order to increase resistance to acid rain.Acid rain induce Pinus massoniana secondary metabolites enzyme express change,such as caffeate O-methyltransferase,putative gibberellin 20-oxidase,phenylcoumaran benzylic ether reductase,3-dehydroquinate synthase.At last,the resistance-related proteins are up regulated to resist acid rain stress.Such as peroxiredoxin,Hsp70,monodehydroascorbate reductase.In a word,acid rain stress has a great impact on various plants' metabolic pathways.In order to ensure the normal growth of the seedling,plant can reduce their energy consumption or activate the other pathway of energy.We also find some stress related proteins are over expression by the supply of calcium.It means that calcium can improve the resistance to aicd rain.