發(fā)布時間：2024-05-31 02:57

　　酸雨是全球性重大環(huán)境問題之一,因其污染可轉移性受到廣泛關注。長酸雨對植物的傷害機理一直是生態(tài)學研究的熱點之一有證據(jù)表明酸雨對植物具有拮抗作用,尤其是對生長、光合活性、抗氧化活性和分子變化的影響。植物對酸雨的反應具有復雜的解毒和耐受的機制。然而,由于植物本身的抗氧化劑和解毒能力有限,在高濃度酸雨水平下常遭受毒害。因此,在這種情況下通過補充外源激素以加強植物解毒系統(tǒng)。褪黑激素(N-乙�；�-5-甲氧基色胺)是一種多功能信號分子,廣泛分布于植物的不同部位,負責刺激幾種生理反應應對不利環(huán)境條件。近年來,褪黑激素已成為植物激素類別的新范例,具有增強了植物對非生物脅迫因素的耐受性,包括熱或冷的溫度,鹽度,干旱,澇害,紫外線輻射以及水和土壤中的化學或金屬的污染物。因此,本研究旨在了解番茄植株對酸雨的脅迫響應,并通過一系列實驗闡明褪黑素在緩解酸雨脅迫中的可能保護機制。重要發(fā)現(xiàn)總結如下:1.為了更好地了解植物脅迫響應酸雨的機理,探討了兩種不同水平的模擬酸雨(SAR)對兩種番茄品種的光合作用、抗氧化酶活性以及非酶抗氧化物質(zhì)含量的影響。結果表明,不同濃度的SAR水平,均顯著降低了番茄品種葉片中植株生長,葉綠素...

【文章頁數(shù)】：170 頁

【學位級別】：博士

【文章目錄】：
List of Abbreviations
摘要
Abstract
1 General introduction and literature review
    1.1 Background of the study
    1.2 Overview of acid rain stress and its consequence on plants
        1.2.1 Causes and formation of acid rain
        1.2.2 Problem of acid rain in plants
        1.2.3 Impact of acid rain on plant growth
        1.2.4 Impact of acid rain on photosynthesis activities in plants……
        1.2.5 Impact of acid rain on antioxidant activities in plants
        1.2.6 Impact of acid rain on molecular changes in plants
    1.3 Melatonin and its overview in plants
        1.3.1 History of melatonin in plants
        1.3.2 Biosynthesis of melatonin in plants
        1.3.3 Melatonin acts as a plant growth regulator
        1.3.4 Melatonin acts as a bio-stimulator and an antioxidant in plant
        1.3.5 Exogenous melatonin and plant stress tolerance
    1.4 Melatonin in plant under acid rain condition
    1.5 Problem statement and justification
    1.6 General objectives
    1.7 Specific objectives
    1.8 Hypothesis
2 Acid rain deposition modulates photosynthesis,enzymatic and non-enzymatic antioxidant activities in tomato
    2.1 Introduction
    2.2 Materials and methods
        2.2.1 Experimental site
        2.2.2 Plant materials and treatments
        2.2.3 Measurement of plant growth
        2.2.4 Determination of chlorophyll and carotenoid content
        2.2.5 Measurement of chlorophyll fluorescence
        2.2.6 Estimation of enzymatic antioxidant compounds
        2.2.7 Assay of hydrogen peroxide(H2O2)and lipid peroxide(MDA)content
        2.2.8 Quantification of total soluble protein and total soluble sugar content
        2.2.9 Determination of total phenolics and flavonoids content……
        2.2.10 Estimation of total proline content
        2.2.11 Measurement of reducing antioxidant activity
        2.2.12 Statistical analysis
    2.3 Results
        2.3.1 Effects of simulated acid rain on growth
        2.3.2 Effects of simulated acid rain on chlorophyll and carotenoid content
        2.3.3 Effects of simulated acid rain on chlorophyll fluorescence….
        2.3.4 Effects of simulated acid rain on enzymatic antioxidant activities
        2.3.5 Effects of simulated acid rain on H2O2 and MDA
        2.3.6 Effects of simulated acid rain on total soluble protein and soluble sugar
        2.3.7 Effects of simulated acid rain on non-enzymatic antioxidant activities
    2.4 Discussion
    2.5 Conclusions
3 Exogenous melatonin mitigates acid rain stress to tomato plants through modulation of leaf ultrastructure,photosynthesis and antioxidant potential
    3.1 Introduction
    3.2 Materials and methods
        3.2.1 Plant materials and treatments
        3.2.2 Measurement of plant growth
        3.2.3 Observation of leaf ultrastructure
        3.2.4 Determination of photosynthesis activities
        3.2.5 Assay of hydrogen peroxide(H2O2)and lipid peroxide(MDA)content
        3.2.6 Estimation of enzymatic antioxidant compounds
        3.2.7 Determination of non-enzymatic antioxidant compounds
        3.2.8 Statistical analysis
    3.3 Results
        3.3.1 Effects of melatonin on growth of tomato plant under SAR stress
        3.3.2 Effects of melatonin on leaf ultrastructure alterations in mesophyll cells and chloroplast of tomato under SAR stress..
        3.3.3 Effects of melatonin on photosynthesis in tomato plant under SAR stress
        3.3.4 Effects of melatonin on H2O2 and MDA content under SAR stress
        3.3.5 Effect of melatonin on enzymatic antioxidant compounds under SAR stress
        3.3.6 Effects of melatonin on nonenzymatic and total antioxidant activity under SAR stress
    3.4 Discussion
    3.5 Conclusion
4 Exogenous melatonin improves fruit quality features,health promoting antioxidant compounds and yield traits in tomato fruits under acid rain stress
    4.1 Introduction
    4.2 Materials and methods
        4.2.1 Plant materials and treatments
        4.2.2 Measurement of fruit quality
        4.2.3 Estimation of enzymatic antioxidant activities,oxidative damage and total antioxidant power
        4.2.4 Quantification of phenolics and flavonoids content
        4.2.5 Estimation of carotenoids
        4.2.6 Quantification of yield
        4.2.7 Statistical Analysis
    4.3 Results
        4.3.1 Impact of exogenous melatonin on fruit qualities under SAR-stress condition
        4.3.2 Impact of exogenous melatonin on antioxidant enzymes in fruits under SAR-stress condition
        4.3.3 Impact of exogenous melatonin on oxidative damage and antioxidant potential in fruits under SAR-stress condition
        4.3.4 Impact of exogenous melatonin on phenolics and flavonoids in fruits under SAR-stress condition
        4.3.5 Impact of exogenous melatonin on carotenoids in fruits under SAR-stress condition
        4.3.6 Impact of exogenous melatonin on yield attributes of tomatoes under SAR-stress condition
    4.4 Discussion
    4.5 Conclusions
5 Transcriptome analysis reveals the impact of exogenous melatonin on differential gene expression,biosynthesis of secondary metabolites and transcript factors in tomato under acid rain stress
    5.1 Introduction
    5.2 Materials and methods
        5.2.1 Plant materials and treatments
        5.2.2 RNA quality examination
        5.2.3 Library preparation for mRNA-sequence
        5.2.4 Library examination
        5.2.5 Library clustering and sequencing
        5.2.6 Transcriptome analysis
        5.2.7 Quantitative Real-time PCR(qRT-PCR)method
        5.2.8 Statistical analysis
    5.3 Results
        5.3.1 RNA quality test results
        5.3.2 RNA-sequencing analysis
        5.3.3 Differentially expressed genes(DEGs)
        5.3.4 Mutual DEGs analysis
        5.3.5 Gene ontology analysis of DEGs
        5.3.6 KEGG pathway analysis of DEGs
        5.3.7 Transcript factors
        5.3.8 Confirmation of gene expression profile through qRT-PCR…
    5.4 Discussion
    5.5 Conclusions
6 General discussion,conclusions and future perspectives
    6.1 General discussion
    6.2 Conclusions
    6.3 Future perspectives
References
Published papers
Acknowledgements



本文編號：3985043