水稻抽穗灌漿期是水稻產量形成的關鍵時期,若葉片提早衰老,會引起碳水化合物供應短缺,籽粒灌漿不足,最終影響水稻的產量和品質。目前生產上種植的水稻類型主要是稻穗大而飽滿高產、超高產雜交稻,因而,籽粒灌漿過程中碳水化合物供求與旗葉早衰之間的矛盾也愈發(fā)突出。施用氮肥可延緩葉片衰老,提高糧食產量,但施氮過多會造成環(huán)境污染、氮肥利用率低、稻米品質劣化、病蟲害以及減產等不利后果。因此,研究水稻籽粒灌漿期葉片早衰發(fā)生機理、探索氮素抑制和延緩葉片衰老的調控機理,對水稻生產具有重要意義。因此,本研究以葉片早衰突變體水稻(psf)及其野生型對照7954(WT)為材料,通過進行不同氮水平處理,探析氮素營養(yǎng)對水稻生育后期葉片衰老過程活性氧積累與莖鞘同化物轉運影響的生理特征。主要研究結果如下:1.缺氮會導致葉片衰老提前發(fā)生,同時加速葉片衰老的進程。低氮(LN)處理可增強OsNCEDs的表達,抑制Osaba8ox2和Osaba8ox3的表達。高氮(HN)處理條件下,葉片ABA含量降低,推遲了葉片衰老的產生和發(fā)展。對水稻葉片進行外源ABA處理,結果顯示,ABA以劑量依賴的方式促進了H₂O

【文章頁數(shù)】：141 頁

【學位級別】：博士

【文章目錄】：
Acknowledgement
Abstract
摘要
Introduction
Background information for the experimental materials
Objectives of the study
Chapter1 Review of literature
    1.1 Regulations of leaf senescence
        1.1.1 Senescence process
        1.1.2 Structural and biochemical changes in leaf during senescence
        1.1.3 Involvement of phytohormone in the regulation of leaf senescence
    1.2 Effect of Nitrogen supply on leaf senescence
        1.2.1 Photosynthetic N metabolism and assimilation
        1.2.2 Photosynthetic carbon(C)metabolism during senescence
        1.2.3 Regulation of C and N metabolism in response to nitrogen availability
    1.3 Effect of N on nonstructural carbohydrate(NSC)reserve and remobilization
    1.4 Molecular approaches to understanding leaf senescence
Chapter2 Relationship of Nitrogen Deficiency-Induced Leaf Senescence with ROS Generation and ABA Concentration in Rice Flag Leaves
    2.1 Introduction
    2.2 Materials and Methods
        2.2.1 Plant materials and nitrogen treatment
        2.2.2 Exogenous ABA incubation experiment in detached leaves
        2.2.3 Measurement of net photosynthetic rate(Pn),chlorophyll content,hydrogen peroxide(H2O2)concentration,malondialdehyde(MDA)level,soluble protein content,and ABA concentration in rice leaves
        2.2.4 Enzymatic assay of glutamine synthetase(GS)and glutamate dehydrogenase(GDH)in rice leaves
        2.2.5 RNA extraction,cDNA preparation,and Quantitative real-time PCR
        2.2.6 Statistical analysis
        2.2.7 Design of key enzyme primers for regulating ABA synthesis and catabolism
    2.3 Results
        2.3.1 Senescence-associated changes in endogenous ABA accumulation,H2O2 production,and activity of key enzymes involving in nitrogen metabolism under different N supply levels
        2.3.2 Transcriptional expression of some key genes involving in ABA biosynthesis and its catabolism for two rice genotypes imposed to different N levels
        2.3.3 Linking the exogenous ABA-regulated leaf senescence with H2O2 generation and N metabolism in rice leaves
    2.4 Discussion
    Conclusion
Chapter3 Senescence-Related Translocation of Nonstructural Carbohydrate(NSC)in Rice Leaf Sheathes Under Different Nitrogen Supply
    3.1 Introduction
    3.2 Materials and Methods
        3.2.1 Plant materials and nitrogen treatment
        3.2.2 Measurement of net photosynthetic rate(Pn)and chlorophyll content in rice leaves
        3.2.3 Determination of soluble sugar content, starch content, and NSC amount in leaf sheaths
        3.2.4 Enzymatic extraction and assays of SPS,FBPase,Susy,GS,GOT,and GPT in leaf sheaths
        3.2.5 Statistical analysis
    3.3 Result
        3.3.1 Effect of N supply levels on leaf senescence and grain yield and also its relation to the NSC translocation and starch accumulation in leaf sheaths
        3.3.2 Positional variations in the NSC amount,total soluble sugar content,and starch accumulation in leaf sheathes under different N supply levels
        3.3.3 Effect of N supply levels on the activities of several key enzymes involving in NSC metabolism in the leaf sheath and its positional variation among three leaf sheaths
    3.4 Discussion
    Conclusion
Chapter4 Senescence-Related Changes in Nitrogen Metabolism and Carbohydrate translocation in Rice Leaves under Different Nitrogen Supply
    4.1 Introduction
    4.2 Materials and Methods
        4.2.1 Plant Materials and Nitrogen Treatment
        4.2.2 Determination of net photosynthetic rate(Pn),chlorophyll content,and Relative conductivity
        4.2.4 Determination Carbon and Nitrogen metabolism-related indicators
        4.2.5 Carbon and Nitrogen Metabolism-related Enzyme Assay
        4.2.6 RNA isolation,cDNA preparation,and Quantitative real-time PCR
        4.2.7 Statistical analysis
    4.3 Results
        4.3.1 Senescence-associated changes in leaf Chla/Chlb,total soluble sugar,sucrose,starch,soluble protein,and total N contents under different nitrogen supply
        4.3.2 N deficiency induced C/N imbalance in the flag leaves during grain filling
        4.3.3 Transcriptional profile of key genes involving in carbon and nitrogen metabolism for two rice genotypes imposed to N deficiency/overfeeding
    4.4 Discussion
Chapter5
    5.1 Major findings
    5.2 Future perspectives
References
List of Publications



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