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Physiological And Molecular Mechanisms Of Adaptation To Arid Environment In The Desert Relict Plant Gymnocarpos Przewalskii

Posted on:2024-03-26Degree:MasterType:Thesis
Country:ChinaCandidate:X Y NiFull Text:PDF
GTID:2530307142965619Subject:Botany
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Gymnocarpos przewalskii Bunge ex Maxim.is an relict plant of the ancient Mediterranean and one of the important constructive specie of desert vegetation.G.przewalskii grow in saline desert or semi-desert areas for a long time,so it has a very high adaptability to abiotic stresses such as drought and barren.Studying the drought adaptability of G.przewalskii is helpful to understand the stress resistance mechanism of desert relict plants.The research object of this study is G.przewalskii,observe its morphological changes during drought stress,and detect and analyze physiological indicators.At the same time,transcriptome sequencing was performed on the G.przewalskii to obtain its transcriptome level genetic information.Screening differentially expressed genes and mining drought-resistant key genes during drought stress,in order to further analyze the drought adaptability mechanism of G.przewalskii.The main research findings are as follows:(1)With the increase of drought stress treatment time,the seedlings of G.przewalskii gradually wilted and the chlorophyll content continued to decline;The content of malondialdehyde continued to increase,the content of hydrogen peroxide decreased first and then increased,while the content of superoxide anion was the opposite.The proline content,catalase activity and superoxide dismutase activity showed an overall upward trend.The ability of scavenge hydroxyl radical was significantly increased(P<0.05).The above results showed that drought stress had a certain effect on the growth of G.przewalskii.In this case,in order to achieve the purpose of balancing osmotic potential and reducing oxidative damage,G.przewalskii not only accumulate proline content,but also increase the activity of superoxide dismutase and hydrogen peroxide.(2)After transcriptome sequencing,44.51 Gb clean reads were obtained from G.przewalskii seedlings.After de novo assembly,102,191 unigenes were generated,of which 3,015 were differentially expressed genes.The functional annotation results of GO and KEGG showed that these differentially expressed genes were related to multiple pathways such as plant growth and development,plant hormones,and stress response.(3)Based on the functional annotation information of differentially expressed genes,the key genes of drought resistance in G.przewalskii were analyzed.A total of 34,32,45,275 and 29 differentially expressed genes were identified,which were related to osmotic regulation,antioxidant enzymes,secondary metabolite synthesis,signal transduction and stress proteins.These abiotic stress-related genes may play a key role in the regulation of drought stress adaptation in G.przewalskii.(4)According to the analysis results of physiological indexes and key genes,the drought adaptability mechanism of G.przewalskii was speculated :The osmotic adjustment ability of G.przewalskii under drought stress maintains the balance of osmotic potential in the body,and the antioxidant capacity reduces oxidative damage.At the same time,the synthesis of secondary metabolites is also involved in the stress response process.Active signaling pathways and a large number of transcription factors play an important regulatory role in the life activities of G.przewalskii.These mechanisms construct the defense system of G.przewalskii in arid habitats.In summary,this paper analyzes the drought resistance mechanism of G.przewalskii from physiological and molecular levels.In this paper,a preliminary understanding of the key genes and pathways of drought resistance in G.przewalskii was formed.This paper not only provides a theoretical basis for the further study of G.przewalskii,but also has positive significance for the study of the molecular mechanism of stress resistance and the protection of germplasm resources.
Keywords/Search Tags:Gymnocarpos przewalskii, Drought stress, Drought stress-resistant physiology, Transcriptome sequencing
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