外源褪黑素缓解苦荞干旱胁迫的生理机制研究

发布时间：2021-09-25 10:35

　　干旱胁迫是全球农业生产的主要障碍之一,常发生在自然界和农业生态系统中。证据表明,干旱胁迫对植物有拮抗作用,尤其是对生长、光合活性、抗氧化活性以及分子水平的变化。然而,由于有限的抗氧化和解毒能力,植物在高强度的干旱胁迫下会遭受毒性。苦荞是一种营养丰富的小杂粮作物,生长在干旱半干旱地区的高寒山地,干旱是一种常见现象,会延缓生长和降低产量,因此,提高作物的抗旱性是获得经济效益的前提。通过补充外源激素可以提供额外的功效来加强植物的解毒系统,以抵抗由外源物质产生的胁迫。多功能信号分子褪黑素（N-乙酰-5-甲氧基色胺）广泛分布于植物的不同部位,在恶劣环境条件下产生许多生理反应。因此,本研究旨在通过一系列试验研究苦荞对干旱胁迫的反应,并阐明褪黑素在缓解干旱胁迫过程中可能存在的保护机制。主要研究结果如下:1、本试验研究了干旱胁迫对苦荞种子萌发、生理和生物学机制的影响,并筛选抗性最强的苦荞品种。对14个品种进行了聚乙二醇（PEG）模拟干旱胁迫处理并设置4个胁迫程度（0%、10%、20%和30%）来评价发芽率和幼苗生长参数。结果表明,在干旱胁迫下,不同品种的发芽率、相对含水量（RWC）和各生长参数存在显著... 

【文章来源】：西北农林科技大学陕西省 211工程院校 985工程院校 教育部直属院校

【文章页数】：188 页

【学位级别】：博士

【文章目录】：
Abstract
摘要
Chapter 1.General Introduction
    1.1 Background of the study
    1.2 Problem statement and justification
    1.3 General objectives
    1.4 Specific Objectives
    1.5 Hypothesis
Chapter 2.Review of Literature
    2.1 Tartary buckwheat
    2.2 Drought stress and its consequences
        2.2.1 Plant stress
        2.2.2 PEG6000
        2.2.3 What is drought stress?
        2.2.4 Concepts and consequences of drought stress on plants
    2.3 Effects of drought stress on plant morphology
        2.3.1 Germination
        2.3.2 Plant growth and development
    2.4 Impacts of drought stress on plant physiology
        2.4.1 Water relations
        2.4.2 Photosynthesis
        2.4.3 Stomata properties under drought stress
        2.4.4 Oxidative stress and enzymatic regulation
        2.4.5 Compatible solutes in the regulation of ROS level
        2.4.6 Secondary metabolism in plants
    2.5 Mechanisms of adaptation to drought stress
    2.6 Gene expression,proteomics,metabolomics
    2.7 Melatonin and its overview in plants
        2.7.1 History of melatonin in plants
        2.7.2 Biosynthesis of melatonin in plants
        2.7.3 Melatonin as a plant growth regulator
        2.7.4 Melatonin acts as a bio-stimulator and an antioxidant in plants
        2.7.5 Exogenous melatonin and plant stress tolerance
    2.8 Melatonin in Tartary buckwheat plant under drought stress condition
Chapter 3.Screening of Drought Tolerant Cultivar under Drought Stress in Tartary Buckwheat Genotypes at Germination Stage
    3.1 Introduction
    3.2 Materials and Methods
        3.2.1 Germination percentage, morphological parameter and relative water content
        3.2.2 Determination of superoxide anion,MDA content,and osmotic solutes
        3.2.3 Quantification of enzymatic antioxidant activity
        3.2.4 Statistical analysis
    3.3 Results
        3.3.1 Effect of PEG induced drought stress on seed germination and morphology
        3.3.2 Measurement of stress tolerance index based on seed germination and morphology
        3.3.3 Effect of PEG induced drought stress on physiological and biochemical mechanisms
        3.3.4 Pearson’s correlation analysis
    3.4 Discussion
    3.5 Conclusions
Chapter 4.Comparative Study on Physiological and Biochemical Mechanism under Drought Stress in Tartary Buckwheat Plant
    4.1 Introduction
    4.2 Materials and Methods
        4.2.1 Assessment of growth parameter
        4.2.2 Estimation of photosynthesis activity and relative leaf water content
        4.2.3 Measurement of stomata properties
        4.2.4 Quantification of osmotic solutes
        4.2.5 Determination of ROS,MDA content and antioxidant activity
        4.2.6 Investigation of non-enzymatic antioxidant activity and total antioxidant capacity
        4.2.7 Statistical analysis
    4.3 Results
        4.3.1 The effect of drought stress on plant growth
        4.3.2 Chlorophyll, carotenoids and chlorophyll fluorescence
        4.3.3 Relative leaf water content
        4.3.4 Stomatal properties
        4.3.5 Osmotic adjustment
        4.3.6 ROS and Malondialdehyde(MDA)content
        4.3.7 Enzymatic antioxidant activities
        4.3.8 Secondary metabolites antioxidant activities and total antioxidant capacity
        4.3.9 Multivariate analysis
    4.4 Discussion
    4.5 Conclusion
Chapter 5.Exogenous Melatonin Modulates the Physiological and Biochemical Mechanisms of Drought Tolerance in Tartary Buckwheat
    5.1.Introduction
    5.2.Materials and Methods
        5.2.1.Measurement of plant growth parameters
        5.2.2.Determination of chlorophyll content and photosynthesis activity
        5.2.3.Leaf Ultrastructure
        5.2.4.Relative leaf water content and osmotic solutes
        5.2.5.Determination of ROS activity,MDA content and Enzymatic antioxidant activities
        5.2.6.Contents of secondary metabolites non-enzymatic antioxidant activity and total antioxidant capacity
        5.2.7.Statistical analysis
    5.3.Results
        5.3.1.Effect of exogenous melatonin on plant growth parameters and relative leaf water content
        5.3.2.The influence of melatonin supplementation on photosynthesis
        5.3.3.Impact of melatonin supplementation on Stomatal properties under drought stress
        5.3.4.Impact of foliar application of melatonin on osmotic solutes content under drought stressed plants
        5.3.5.Effect of exogenous melatonin on ROS activity and MDA content
        5.3.6.Effect of exogenous melatonin on enzymatic antioxidant activities
        5.3.7.Impact of melatonin supplementation on enzymatic and non-enzymatic secondary metabolites and total antioxidant capacity
        5.3.8 Evaluation of melatonin effects under drought stress by heatmap hierarchical clustering and principal component axis analysis
    5.4.Discussion
    5.5 Conclusions
Chapter 6.Transcriptome Profiles Revealed the Role of Melatonin in Inducing Drought Tolerance in Tartary Buckwheat Plant
    6.1.Introduction
    6.2.Materials and Methods
        6.2.1.Plant materials and treatments
        6.2.2.RNA extraction
        6.2.3.Library preparation,Clustering and RNA-sequencing
        6.2.4.Transcriptome analysis
        6.2.5.Quantitative real-time PCR(q TPCR)method
        6.2.6.Statistical analysis
    6.3.Results
        6.3.1 RNA quality test results
        6.3.2 RNA-sequencing analysis
        6.3.3 Differentially expressed genes(DEGs)
        6.3.4 Mutual DEGs analysis
        6.3.5 Gene ontology analysis of DEGs
        6.3.6 KEGG pathway analysis of DEGs
        6.3.7 Transcript factors
        6.3.8 Confirmation of gene expression by q RT-PCR
        6.3.9 Photosynthesis pathway
        6.3.10 Carotenoid biosynthesis
        6.3.11 Biosynthesis of secondary metabolite
    6.4 Discussion
    6.5 Conclusion
Chapter 7 General Discussion,Conclusions and Future Perspectives
    7.1 General discussion
    7.2 Conclusions
    7.3 Future perspectives
References
Nomenclature
Acknowledgement
About the Author
List of Published Articles



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