Research On Physiological Responses To Salt And Drought Stress In Cerasus Humilis And Its Transcriptome Sequencing Analysis

To research on the adaptive mechanism and investigate the physiological response and biochemistry pathway to Cerasus humilis tolerance in salt and drought stress, we measured series of physiological and biochemical parameters in salt stress, such as antioxidant enzyme activities, ion content, respiration parameters and the related enzymatic activity, and quantitative analysis of the gene NHX1and CDPK which are involved in salt stress response by RT-PCR technology. Then to analysis and discuss the transcriptome sequencing date under the drought stress. The experiment results were as follows:1Salt stress increase antioxidant enzyme activities(SOD、POD、APX、GR), improving the adaptation ability of plant to adversity. The membrane lipid peroxidation and electrolytic leakage rate aggravated. It is showed that drought stress had a certain influence on plants. Total respiration was increased, alternative respiration and cytochrome respiration both change. Alternative respiration was enhanced and cytochrome respiration was decreased during the stress.2Salt stress makes K+/Na+content in both leaves and roots reduced, and Na+content accumulated gradually, K+content lessoned observably. Ca2+and Mg2+content declined slightly, Cu2+and Zn2+content are not changed obviously. Studies have shown that the ion content in plants break the ion balance, make a large number of ion accumulation and erosion, it will emerge a single salt poisoning and ionic outflow phenomenon and not be conducted the physiological metabolism in plant.3By RT-PCR technique to NHX1gene and CDPK gene expression analysis under salt stress revealed that two kinds of gene expression were raised, it may be a kind of resistance of plants to salt stress response.4Under the drought condition, the content of soluble sugar accumulated, thus it will contribute to osmotic regulation, and ease drought damage to plants. And pyruvic acid content increased, make to participate in the Krebs cycle of substrates adequated and suitable for respiration. The study revealed Cytochrome c oxidase(COX), malic dehydrogenase(MDH) and citric acid dehydrogenase(CS) activity decreases, but the malic dehydrogenase activity changes obviously, citric acid dehydrogenase reduced slightly, it was suggested that respiration related enzyme activity was affected due to drought. Sugar glucose-6-phosphate dehydrogenase (G-6-PDH) and glucose6-phosphate-acid dehydrogenase (6-P-GDH) activity increase, it may cause respiratory metabolism from the TCA cycle to the PPP metabolic pathways, makes G-6-PDII and6-P-GDH activity increases.5We research the transcriptome date of Cerasus humilis by High-throughput sequencing technology, and add up each transcript length and sequence preliminarily, then obtain the Unigene sequences by assembling the clustering. The results showed that the sequenece length of transcription was from500to1000bp in major, the proportion of length of Unigene are slightly different. There are a large number of differential expression genes. Under drought stress, there were1131genes up-regulation compare with the control,986genes down-regulation. To classify and annotate Unigene by COG, GO, KEGG, further study on the gene expression in transcriptional level and the related molecular function and metabolic pathways, it will basis for the research of gene and metabolic levels.