花生叶片衰老与活性氧代谢

高产花生品种鲁花11号和辐8707叶片衰老研究表明，花生叶片展开至衰老过程中，超氧化物歧化酶（SOD），过氧化氢酶（CAT），过氧化物酶（POD）活性的变化趋势均可用Y＝A＋Bx Cx^2拟合；叶片丙二醛（MCA）含量，活性氧（O^-2)释放速率和质膜透性变化符合Y=Ae^Bx.叶片展开后25－30d至55－60d为叶片缓衰期，叶片展开55－60d以后为叶片速衰期，两品种相比，辐8707叶片的衰老早于鲁花11。     

水稻叶片衰老研究进展

叶片的衰老是植物生长发育的最后阶段,是一种基因编码的程序性事件。但在农业生产上,水稻叶片的过早衰老已经成为制约水稻发展的重要因素,研究水稻叶片的早衰对水稻育种改良具有重要意义。本文综述了近年来国内外有关水稻叶片衰老研究结果,主要包括水稻叶片衰老的机理、特征、影响叶片衰老的因子、常用的水稻叶片衰老的生理生化指标等,同时介绍了近年来有关水稻叶片衰老遗传研究进展。     

水稻叶片衰老的分子机理及研究进展

水稻作为我国最主要的粮食作物,已知在生育期允许的范围内,适当延缓水稻叶片早衰,对产量有很大的作用。中国是最早利用水稻杂种优势的国家,杂交稻尚存在结实率偏低、空秕率较高的问题。有研究表明,叶片和根系早衰是造成这一现象的主要原因。有些杂交稻通过推迟停水期来延缓衰老,并推迟收割期,有明显的增产效果,每延迟一天,平均增产1%左右。1　叶片衰老期间基因表达的变化基因表达参与叶片衰老的调控,在转录水平上,衰老期间的基因表达存在4种模式,即基因激活、表达增强、部分抑制和完全抑制。这4种模式在衰老期间体现在ｍＲＮＡ水平上就是上…     

水稻结实期间叶片衰老与膜脂过氧化的关系

 以结实期间的稻为材料，在抽穗开花期通过剪去穗部部分枝梗和全穗等处理后，测定作为叶片衰老指标的叶绿素和蛋白质含量及作为膜脂过氧化指标的丙二醛含量的变化，探讨了水稻结实期间叶片衰老与膜脂过氧化之间的关系。试验结果指出，在水稻抽穗开花期间，剪去穗部枝梗或整个穗子，叶片中的叶绿素和蛋白质含量下降速率在处理后的7 d内就开始明显减慢，而MDA含量增加速率只有在处理7 d后才开始减缓，SOD活性并不因剪穗处理而有所提高。表明因剪穗(或穗部枝梗)而导致的叶绿素和蛋白质含量的变化早于MDA含量的变化，与SOD活性的变化无直接关系。说明在结实期间，水稻叶片在衰老过程中表现出的叶绿素和蛋白质含量的下降，并不主要是由于SOD的活性降低而导致膜脂过氧化作用增强所造成的结果，SOD活性下降和MDA含量的增加可能与叶绿素及蛋白质含量减少一样，只是叶片衰老开始后的一种结果，而非引起叶片衰老的原因。     

库源比对杂交水稻叶片衰老的影响

在水稻开花期间，通过剪去穗部部分枝梗和叶片等处理,形成不同的源库比，研究其与叶片衰老的关系，结果表明，亚种间杂交水稻赣化7号源库矛盾大，叶片衰老，降低库源比，能明显减缓其叶片中蛋白质，叶绿素含量下降和丙二醛含量的升高，说明杂交水稻叶片早衰与其为源比较大有关。     

钙对延缓杂交水稻叶片衰老的作用机理

以叶绿素、蛋白质含量为衰老的生理指标，研究了不同ｐＨ、Ｃａ２＋对杂交水稻叶片衰老的作用。结果表明，不同ｐＨ影响叶绿素和蛋白质含量，最适ｐＨ为６．０；此条件下的Ｃａ２＋浓度为０．０１～２０．００ｍｍｏｌ／ｌ，低浓度的Ｃａ２＋提高叶片中叶绿素和蛋白质含量，提高超氧化物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）、过氧化物酶（ＰＯＤ）活性，降低丙二醛（ＭＤＡ）含量；随着Ｃａ２＋浓度升高，则作用减弱；最适浓度为０．１ｍｍｏｌ／ｌ。Ｃａ２＋能延缓杂交水稻叶片的衰老，主要原因是由于Ｃａ２＋能提高叶片中活性氧防御酶的活性，降低活性氧的伤害作用。     

稻田冬季保护性耕作条件下的土壤酶活性与水稻成熟期叶片衰老和籽粒产量之间的关系

 为研究稻田冬季保护性耕作不同种植模式对土壤酶活性以及水稻成熟期叶片衰老的影响, 设计了5种种植模式：免耕直播稻草全程覆盖马铃薯（T1）、免耕直播黑麦草（T2）、免耕直播油菜（T3）、免耕直播燕麦草（T4）和空闲（CK）,供试品种为杂交组合国稻6号。与对照（CK）相比,T1、T2和T3处理均可显著提高土壤蛋白酶、中性磷酸酶、过氧化氢酶以及转化酶活性,尤其是T1处理,其土壤酶活性明显高于其他处理,而T4处理与对照相比,差异不明显。T1、T2和T3处理均可有效延缓水稻成熟期剑叶的衰老,主要表现为成熟期剑叶中的超氧化物歧化酶、过氧化物酶活性、可溶性蛋白质和叶绿素含量下降缓慢,丙二醛含量上升的幅度较小,相对于对照（CK）,差异均达显著水平。在本试验条件下,土壤酶对水稻叶片衰老的影响程度依次为蛋白酶>过氧化氢酶>中性磷酸酶>转化酶。叶片衰老对水稻产量的影响主要表现在灌浆中后期。     

花生不同叶位叶片衰老差异的研究

在大田条件下，研究了高产花生品种鲁花11号和辐8707主茎不同叶位叶片衰老的差异。结果表明：花生主茎展开18片叶(饱果期)时，主茎叶片叶绿素含量、净光合速率(Pn)、可溶性蛋白质含量(Pr)、超氧化物歧化酶(POD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性逐渐升高，顶3-6叶达最大值，向下逐渐降低。叶片丙二醛(MDA)含量、活性氧(O2^-)释放速率随叶位的降低逐渐升高，顶6叶后开始迅速升高。花生主茎顶1-3叶属快速生长叶，顶4-6(7)叶属缓慢衰老叶，顶7(8)-10叶属迅速衰老叶。两品种间差异不大，辐8707叶片的衰老稍早于鲁花11号。     

杂交稻根系代谢活性与叶片衰老进程相关研究

用木村Ｂ营养液水培威优３５、威优４９和常规稻湘矮早９号，测定叶片和根系ＳＯＤ活性，可溶性蛋白质含量及叶片叶绿素含量的动态变化。结果表明：叶片ＳＯＤ活性、可溶性蛋白质含量分别在雌雄蕊原基形成期和抽穗期出现峰值，而根系ＳＯＤ活性分别在二次枝粳原基分化期、孕穗后期和乳熟期出现峰值。叶片ＳＯＤ活性，可溶性蛋白质含量、叶绿素含量的降解速率，从抽穗至乳熟期杂交稻大于常规稻，并与空秕率成显著正相关；而从乳熟期至完熟期，则常规稻大于杂交稻，并与粒重成极显著负相关。     

Relationship Between Changes in Leaf Endogenous Hormone Contents and Senescence During Grain Filling Stage of a Rice Hybrid and its Parents

A major problem in hybrid rice production is the occurrence of leaf senescence during the grain filling stage that can result in reduction of yield. Changes in contents of several endogenous hormones are related to leaf senescence. The relationship between endogenous hormones and leaf senescence in the rice hybrid Tiyou 418 and its parents Tijin and C418, was undertaken for investigation. Indicators of leaf senescence, including superoxide dismutase (SOD) activity, malondialdehyde (MDA) accumulation and chlorophyll content, as well as the contents of abscisic acid (ABA), zeatin riboside (ZR), gibberellin (GA1/3) and auxin (IAA) in the leaves were determined. Different rates of leaf senescence were observed in the three materials. Senescence occurred earliest and fastest in Tijin, followed by Tiyou 418 and then C418. A similar trend was recorded in ABA, ZR, and IAA contents during the grain filling stage in the three materials. Changes in (GA1/3 ZR IAA)/ABA ratios were also similar, being quite stable during the early stage of leaf senescence, and decreasing markedly during the late stage. The ratio declined more dramatically in Tijin, in accordance with its faster leaf senescence. The results suggest that the ratio of (GA1/3 ZR IAA)/ABA regulates chlorophyll content, SOD activity, MDA content and membrane lipid peroxidation. It is postulated that endogenous hormones may play a role in the regulation of leaf senescence in a systematic way.     

杂交粳稻屉优418及其亲本灌浆期叶片内源激素含量变化与衰老之间的关系

以杂交水稻屉优418及其亲本屉锦和C418为材料,研究了生育后期叶片内源激素含量变化与衰老之间的关系。结果表明杂交水稻及其亲本剑叶中ABA、GA1/3、ZR和IAA含量变化趋势基本一致。3个材料的（GA1/3+ZR+IAA）/ABA的比值变化总的趋势也基本相同,前期较平稳,后期比值迅速下降。在生育后期,屉优418和C418的（GA1/3+ZR+IAA）/ABA比值下降速率较慢,与衰老相对较慢一致;而屉锦的（GA1/3+ZR+IAA）/ABA比值下降速率较快,与其衰老较快相一致。     

Relationship Between Changes in Leaf Endogenous Hormone Contents and Senescence During Grain Filling Stage of a Rice Hybrid and its Parents

A major problem in hybrid rice production is the occurrence of leaf senescence during the grain filling stage that can result in reduction of yield. Changes in contents of several endogenous hormones are related to leaf senescence. The relationship between endogenous hormones and leaf senescence in the rice hybrid Tiyou 418 and its parents Tijin and C418, was undertaken for investigation. Indicators of leaf senescence, including superoxide dismutase (SOD) activity, malondialdehyde (MDA) accumulation and chlorophyll content, as well as the contents of abscisic acid (ABA), zeatin riboside (ZR), gibberellin (GA1/3) and auxin (IAA) in the leaves were determined. Different rates of leaf senescence were observed in the three materials. Senescence occurred earliest and fastest in Tijin, followed by Tiyou 418 and then C418. A similar trend was recorded in ABA, ZR, and IAA contents during the grain filling stage in the three materials. Changes in (GA1/3 ZR IAA)/ABA ratios were also similar, being quite stable during the early stage of leaf senescence, and decreasing markedly during the late stage. The ratio declined more dramatically in Tijin, in accordance with its faster leaf senescence. The results suggest that the ratio of (GA1/3 ZR IAA)/ABA regulates chlorophyll content, SOD activity, MDA content and membrane lipid peroxidation. It is postulated that endogenous hormones may play a role in the regulation of leaf senescence in a systematic way.     

养分胁迫对籽粒灌浆期水稻叶片衰老影响的蛋白质组学分析

 采用蛋白质组学分析技术,对养分胁迫下杂交水稻威优916功能叶片蛋白质组差异表达进行研究,以揭示养分胁迫影响籽粒灌浆期水稻衰老的分子机理。经双向电泳分离,从功能叶中获得34个差异表达蛋白质,其中26个蛋白质功能得到鉴定,包括11个参与光合作用蛋白质,4个参与呼吸作用蛋白质,10个参与抗氧化及信号传导蛋白质和1个未知功能蛋白质。分析结果表明,养分胁迫下,灌浆期水稻叶片光合作用及呼吸作用显著下降;清除活性氧类蛋白质表达量下调,活性氧生成蛋白质及胁迫信号传导蛋白质表达量上调,水稻抗性减弱,叶片中活性氧积累,水稻衰老加剧。     

Effects of Aerated Irrigation on Leaf Senescence at Late Growth Stage and Grain Yield of Rice

With the japonica inbred cultivar Xiushui 09,indica hybrid combinations Guodao 6 and Liangyoupeijiu as materials,field experiments were conducted in 2007 and 2008 to study the effects of aerated irrigation on leaf senescence at late growth stage and grain yield of rice.The dissolved oxygen concentration of aerated water evidently increased and decreased at a slow rate.The soil oxidation-reduction potential under aerated irrigation treatment was significantly higher than that of the CK,contributing to significant increases in effective panicles,seed setting rate and grain yield.In addition,the aerated irrigation improved root function,increased superoxide dismutase activity and decreased malondialdehyde content in flag leaves at post-flowering,which delayed leaf senescence process,prolonged leaf functional activity and led to enhanced grain filling.     

杂交稻旗叶衰老过程中超氧自由基与超氧物岐化酶活性的变化

The O₂^- production, scavenging capacity, photooxidation, protein content, and SOD activity were studied in leaves of Yayou 2 (indica-japonica hybrid rice) and Shanyou 63 (indica hybrid rice) at filling stage. It was shown that protein content decreased gradually with days of heading in two varieties in natural condition, and the decrease in Shanyou 63 was more than that in Yayou 2. The rate of O₂^- production and SOD activity increased from heading to 20 days after heading, then decreases but still maintained certain levels until 30 days after heading in two varieties. O₂^- production rate in Shanyou 63 was more than that of Yayou 2, but SOD activity was contrary in two varieties. In addition, the change of O₂^- and SOD under photooxidation condition was consistent with the tendency above under natural condition. It was also shown that there was negative correlation between protein degradation and O₂^- / SOD in the process of senescence in flag leaves after 20 days of heading. It is suggested that O₂^-/SOD could be used as an index of scavenging ability for O₂^- during senescence in rice.     

超级杂交稻穗分化期叶片比叶重与光合速率的关系

以超级杂交稻两优培九和中优6号作为研究材料, 研究了不同密度处理叶片比叶重和光合速率的关系,结果表明叶片比叶重和光合速率不同密度之间有明显差异,相同品种叶片的比叶重与光合速率呈线性正相关。     

Correlation of Leaf and Root Senescence During Ripening in Dry Seeded and Transplanted Rice

Dry seeding is a resource-saving rice establishment method. With an equivalent yield, dry seeded flooded rice (DSR) has been considered as a replacement for traditional transplanted flooded rice (TFR). However, the differences in leaf and root senescence during grain filling between DSR and TFR were seldom identified. In this study, the root length, root tip number and leaf senescence of rice varieties Huanghuazhan and Yangliangyou 6 during ripening were compared between DSR and TFR. Results showed that top three leaves in DSR had the characteristics of relatively lower SPAD value, lower N content and premature leaf senescence. In addition, both the total root length and total root tip number of DSR were significantly lower than those of TFR. In conclusion, premature and quick leaf senescence was related with inadequate root length and root tip number during ripening, which might result from the deficiency of nitrogen supply in DSR. Techniques on improving leaf nitrogen status and delaying the leaf senescence during grain-filling in DSR should be developed in future researches.