The Physiological Response And Transcriptome Analysis Of Meng Yuan Cerasus Humilis Under Drought Stress

Meng Yuan Cerasus humilis originated from arid and semi-arid areas in central and western Inner Mongolia,and has very strong drought resistance,but the current drought resistance mechanism of Meng Yuan Cerasus humilis is not clear.In this experiment,Meng Yuan Cerasus humilis was used as the test material,and the pot water control experiment was used to simulate different degrees of drought stress environment.By detecting changes in leaf stomata,leaf anatomical structure and cell ultrastructure,changes in photosynthetic parameters and physiological and biochemical indicators,gene expression changes under drought stress,and from the leaf morphology,physiology and molecular level to study the response mechanism of Meng Yuan Cerasus humilis under drought stress,and lay the foundation for in-depth study of the molecular mechanism of drought resistance in Meng Yuan Cerasus humilis.The main results achieved are as follows:1.With the aggravation of drought stress,the stomatal opening of leaves of Meng Yuan Cerasus humilis gradually decreased until closed,the thickness ratio of palisade tissue to spongy parenchyma increased,the ultrastructure of mesophyll cells changed obviously and serious injury symptoms appeared,the chloroplast membrane system collapsed,the matter in the nucleus flowed out,the outer mitochondrial membrane disappeared and the cell wall became thinner.2.With the aggravation of drought stress,both net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs)and water use efficiency(WUE)showed a significant downward trend,while the intercellular CO2 concentration(Ci)increased significantly.Chlorophyll content increased first and then decreased,the highest in mild stress(3.10 mg·g-1).3.The principal component analysis method was used to comprehensively evaluate 10 physiological and biochemical indexes of Meng Yuan Cerasus humilis under different drought stress:Malondialdehyde content(MDA),proline content(Pro),soluble protein content(SP)and activities of superoxide dismutase(SOD)can be used as the main indicators for drought identification and screening of Meng Yuan Cerasus humilis;Carotenoid content(Car)can be used as a secondary indicator;the cumulative contribution rate reaches 86.641%.4.Using transcriptome sequencing technology to sequence and assemble two materials from the control group(CK)and drought stress group(MD),a total of 58893 Unigenes were obtained with an average length of 956 bp.Compared with public databases,there were 42073(71.4%)Unigene received effective functional annotations.5.The control group and drought stress treatment group screened 2008 differentially expressed genes(DEGs),of which 1038 were down-regulated and 970 were up-regulated.KEGG significant enrichment analysis screened out 8 pathways for significant enrichment,mainly involved in the synthesis and transformation of antioxidant compounds,protein synthesis and photosynthesis.6.Analysis of the eight DEGs annotated into the map00195 photosynthesis pathway revealed that the gene expression of the drought stress group was significantly higher than that of the control group,and all of them were up-regulated.