【作者】 周小梅；

【导师】 赵运林； 周朴华；

【作者基本信息】 湖南农业大学 ， 植物学， 2008， 博士

【摘要】 以水稻品种旱116、嘉早935和湘早籼32号为材料,不同浓度的PEG6000模拟自然干旱及自然干旱对水稻进行渗透胁迫处理,添加多胺及多胺合成抑制剂等外源物质,研究了渗透胁迫下水稻生长,多胺代谢,活性氧及相关酶活性的变化及多胺在渗透胁迫信号转导过程中的地位,探讨了多胺在水稻适应渗透胁迫过程中的生理调节功能,主要研究结果如下:1、渗透胁迫促进水稻幼苗根系干物质的积累和根冠比的增大,在渗透胁迫下水稻幼苗体内的Put、Spd和Spm含量明显上升,且抗旱性强的旱116的上升幅度明显大于湘早籼32号,Put、Spd和Spm含量与根冠比呈一定的正相关,表明Put、Spd和Spm参与了水稻幼苗对渗透胁迫的适应性代谢。外源Spm处理增加了水稻体内Put、Spd和Spm的含量,减缓渗透胁迫对水稻的伤害,而多胺合成抑制剂MGBG和D-Arg处理则明显抑制水稻体内Put、Spd和Spm含量的上升,加重渗透胁迫的伤害程度,外源Put能明显逆转D-Arg的抑制效应。渗透胁迫下水稻幼苗体内Put、Spd和Spm含量的变化可作为苗期抗旱性的鉴定指标。2、渗透胁迫诱导水稻胚芽鞘和幼根中的Put、Spd和Spm含量的上升,对抗旱性强的旱116和嘉早935的促进作用更明显,外源MGBG和D-Arg抑制渗透胁迫下水稻体内Put、Spd和Spm含量的上升,加重渗透胁迫对胚芽鞘和幼根的伤害程度,而外源Spd处理明显促进胚芽鞘中Put、Spd和Spm含量的升高,减轻渗透胁迫的伤害。外源Spd处理虽明显促进幼根中Put、Spd和Spm含量的升高,但却加重渗透胁迫的伤害程度。渗透胁迫下胚芽鞘中PAs含量的变化可作为水稻芽期抗旱性鉴定的生理指标。3、对分蘖期进行渗透胁迫主要影响水稻的分蘖数,进而影响后期的产量。在渗透胁迫,外源Spm及MGBG的处理下,旱116叶片中Put、Spd和Spm的含量与分蘖数的变化率及抗旱系数呈极显著的正相关,表明在渗透胁迫下Put、Spd和Spm含量的上升有利于提高分蘖期水稻的抗旱性,与苗期的试验结果相一致。渗透胁迫下水稻叶片中Put、Spd和Spm含量的变化可作为分蘖期抗旱性的鉴定指标。4、渗透胁迫下水稻体内PAO活性随Put、Spd和Spm含量的变化而变化,且呈一定的正相关,细胞壁结合态PAO活性明显高于游离态PAO,是游离态PAO活性的9.8-15.65倍,且具一定的相关性（R=0.952）,表明水稻体内PAO绝大部分定位于细胞壁上。5、在渗透胁迫,外源Put和MGBG的处理下,水稻幼苗叶片中SAMDC、ADC活性的变化与Put、Spd和Spm含量变化趋势基本一致,而ODC活性基本上没有明显变化,表明渗透胁迫下水稻幼苗叶片中Put的合成主要是经ADC的脱羧而形成。6、渗透胁迫诱导水稻叶片中Put、Spd和Spm含量的上升,促进叶片中SOD、POD的活性的升高及Vc的含量的增加来降低H₂O₂和丙二醛的水平,降低活性氧对水稻幼苗的伤害。7、渗透胁迫下水稻幼苗根中Put、Spd和Spm的积累受ABA、NADPH氧化酶产生的活性氧和Ca²⁺的调节,Put、Spd和Spm可调节质膜NADPH氧化酶活性,表明可能存在Osmotic Stress→ABA→PAs→NADPH oxidase→H₂O₂→Ca²⁺的信号转导途径,Put、Spd和Spm与NADPH氧化酶产生的活性氧及Ca²⁺水平之间可能存在有交叉对话,Ca²⁺与活性氧也存在交叉对话。更多还原

【Abstract】 Rice cultivars of Han 116,Jiaozao935 and Xiangzaoxian32 were used as experimental materials, treated rice cultivars with different concentration PEG-6000 and natural drought,followed by treatment of polyamine,polyamine synthesis inhibitor to the solution.Then studied on growth,polyamine metabolism,active oxygen and change of some related enzymes activity and signal transduction of rice under osmotic stress.Physiological regulation role of polyamine in its adaptation to osmotic stress was explored.Main reseach results were as follows:1. Accumulation of dry weight in roots,R/S and contents of Put,Spd and Spm of rice seedlings were significantly increased under osmotic stress,and Han116 increased more markedly than Xiangzaoxian32,positive correlation between Put,Spd and Spm contents and R/S ,which showed that Put,Spd and Spm were involved in adaptation metabolism.Exogenous Spm treatment could significantly promote Put,Spd and Spm contents and alleviate harm of osmotic stress,but MGBG and D-Arg treatment significantly inhibited Put,Spd and Spm contents and aggravated it.Exogenous Put could reverse inhibitory effect of D-Arg.Change of Put,Spd and Spm contents of seedlings would be regarded as an indicator of identifying drought -resistance at seedling stage under osmotic stress2.Osmotic stress led to notable increase of Put,Spd and Spm contents in coleoptiles and young roots of rice,and Han116 and Jiaozao935 increased more markedly than Xiangzaoxian32. Exogenous MGBG and D-Arg inhibited Put,Spd and Spm contents and aggravated harm on coleoptiles and young roots under osmotic stress,while exogenous Spd treatment remarkably enhanced Put,Spd and Spm contents in coleoptiles and mitigated harm degree of osmotic stress. Though exogenous Spd treatment could increase Put,Spd and Spm levels in young roots , aggravate harm degree of osmotic stress on young roots. Change of PAs contents in coleoptiles could be considered as a physiological indicator of identifying drought - resistance at bud stage under osmotic stress .3. Osmotic stress mainly effected tillering number at tillering stage and then effected yield . Significantly positive correlation between Put,Spd and Spm contents and change rate of tillering numbers and yield maintenance ratio under exogenous Spm and MGBG treatment demonstrated that increase of Put,Spd and Spm levels helped improve drought - resistance of rice at tillering stage,which agreed with experimental results at seedling stage.It manifested that change of Put,Spd and Spm levels could be believed as an indicator of identifying drought - resistance at tillering stage under osmotic stress. 4.PAO activity changed with the change of Put,Spd and Spm levels under osmotic stress.It found there was some correlation between PAO activity and Put,Spd and Spm contents. Cell wall-localized PAO activity was notably higher than free PAO,which was 9.8-15.65 times higher than that of free PAO.There was also certain correlation between binding PAO activity and free PAO activity （R=0.952） ,which illuminated that PAO of rice largely located cell wall.5.There was nearly the same tendency between the change of SAMDC,ADC activity and Put,Spd and Spm contents under osmotic stress, exogenous Put and MGBG treatment while ODC activity essentially remained unchanged. It declared that synthesis of Put mainly went through decarboxylation of ADC6.Osmotic stress induced to raise contents of Put,Spd and Spm , encouraged to enhance activity of SOD,POD and increase content of Vc in order to decrease levels of MDA and H₂O₂-Then reduced harm of active oxygen on rcie seedlings.7.The osmotic stress-induce accumulation of Put,Spd and Spm in roots of rice seedlings was regulated by ABA,H₂O₂ and Ca²⁺,while Put,Spd and Spm might regulate the activity of plasma membrance-bound NADPH oxidase.The results implied that there might be a signaling pathway which include osmotic stress→ABA→PAs→PM NADPH oxidase→H₂O₂→Ca²⁺,and there might be cross-talk between PAs and NADPH oxidase-induces ROS and Ca²⁺,and there might be alsocross-talk between ROS and Ca（2+）.更多还原