超高产水稻组合‘培矮64S/E32’的耐光氧化特性及其机理

甲基紫精(MV)介导的光氧化导致两个水稻品种‘汕优63’(目前我国大面积推广的杂交水稻)和‘培矮64S/E32’(新培育的超高产杂交水稻)细胞电解质渗漏率都增加,前者增加的量大于后者,显示‘培矮64S／E32’的细胞膜系统受光氧化的伤害小。光氧化条件下,‘培矮64S／E32’仍能维持较高的光合放氧能力(Amax,φi)、PSⅡ活性(Fv/Fm、φPSⅡ)和叶绿素荧光猝灭系数(qP、MPQ),而且光氧化引起‘培矮64S／E32’这些参数的下降幅度也小。另外,光氧化导致了两个水稻品种抗氧化酶SOD和APX活性增加,‘培矮64S／E32’增加的幅度约为‘汕优63’的3倍。结果 表明超高产水稻具有更强的耐光氧化能力。     

超高产杂交稻剑叶中C4途径酶活性和稳定碳同位素分异作用的变化

以超高产杂交水稻(Oryza sativa L.)"培矮64S/E32"和多年来大面积推广的杂交稻"汕优63"为材料,研究孕穗后剑叶中C4途径酶和对稳定碳同位素分异作用的变化.结果表明,籽粒灌浆期(移栽后68～75 d)的两个品种剑叶中NADP-MDH活性最高,随后下降;超高产杂交水稻"培矮64S/E32"的NADP-MDH的活性明显高于"汕优63";PEPCase和NADP-ME活性在黄熟期之前的叶片中持续上升.不同生育期的叶片与籽粒的△1aC值相近(19.49‰～19.82‰),在成熟期时较高.超高产水稻"培矮64S/E32"叶片的平均△13C值比"汕优63"高0.43‰.     

超高产杂交稻剑叶中C4途径酶活性和稳定碳同位素分异作用的变化

以超高产杂交水稻(Oryza sativa L．)“培矮64S／E32”和多年来大面积推广的杂交稻“汕优63”为材料,研究孕穗后剑叶中C4途径酶和对稳定碳同位素分异作用的变化。结果表明,籽粒灌浆期(移栽后68～75d)的两个品种剑叶中NADP—MDH活性最高,随后下降;超高产杂交水稻“培矮64S／E32”的NADP-MDH的活性明显高于“汕优63”;PEPcase和NADP—ME活性在黄熟期之前的叶片中持续上升。不同生育期的叶片与籽粒的△^13C值相近(19．49‰～19．82‰),在成熟期时较高。超高产水稻“培矮64S／E32”叶片的平均△^13C值比“汕优63”高0．43‰。     

自然条件下不同高产稻生育后期剑叶叶绿素荧光和膜脂过氧化的表现

以籼型(Oryza sativa L.)杂交组合汕优63为对照,以中粳9516、两系亚种间杂交组合培矮64S/E32、培矮64S/9311、亚种间三系杂交稻冈优881和两系杂交组合X07S/紫恢100为材料,研究其在生育后期(抽穗-成熟)自然条件下剑叶的叶绿素衰减、CO2交换、叶绿素荧光参数和膜脂过氧化表现.结果表明: 水稻在生育后期伴随叶绿素衰减,其叶内的原初光化学效率Fv/Fm、PSⅡ非环式电子传递效率ΦPSⅡ、电子流传递速率ETR都有相应地下降,这种光能转化的障碍使多余的光能传递给PSⅡ的还原侧,产生O(-)/(*)2累积,发生膜脂过氧化和MDA的积累,引起光合色素及光合膜的破坏,发生光氧化早衰.这种现象在品种间有明显差异,耐光氧化的粳稻9516,其叶内的 Fv/Fm、ΦPSⅡ、ETR、qP下降较少,具有较稳定的光能转化能力,不易早衰,具有较高的结实率;而对光氧化敏感的籼稻汕优63其叶内的Fv/Fm、ΦPSⅡ、ETR,光化学猝灭参数qP下降较多,易发生膜脂过氧化,导致叶片早衰,影响水稻灌浆结实和产量;而二系的和三系的杂交稻的耐光氧化特性和早衰表现居于中间.从水稻超高产育种的角度出发,在目前株型良好的基础上,兼顾杂种优势和防止早衰两方面考虑,在母本中利用粳型或带有粳型基因的不育系是育种上一个值得重视的策略.     

超高产杂交稻剑叶衰老过程中PSII功能的变化

对田间自然条件下培矮64S/E32和对照汕优63的剑叶衰老过程中PSII光化学效率、光能耗散和叶黄素循环组分的动态变化进行了研究.结果表明,水稻剑叶衰老过程中PSⅡ光化学效率(F/Fm)、PSII量子产量(φPSII)、光化学猝灭系数(qP)和光合速率(Pn)均降低,但非辐射热耗散(NPQ)、叶黄素循环库和中午时的脱环氧化状态则升高.移栽后55-75 d两品种剑叶的φPSII和qP变化相近,此后培矮64S/E32比汕优63下降缓慢.在生育后期的衰老过程中培矮64S/E32剑叶的PSII功能比汕优63下降慢,并具有更高的光能利用效率.     

在光氧化条件下不同类型高产稻的叶绿素荧光特性和膜脂过氧化特点

用不同类型高产稻(Oryza sativa L.)粳稻9516、具有粳型成分的两系法亚种间杂交稻培矮64/E32、两优培九(培矮64/9311)和籼型杂交稻X07S/紫恢100、冈优881、汕优63为材料,研究了孕穗期叶片在光氧化条件下的叶绿素荧光特性和膜脂过氧化表现.光氧化处理后,与籼型杂交稻比较,粳稻和具有粳型组分的亚种间杂交稻的PSⅡ原初光化学效率(Fv/Fm)、PSⅡ的线性电子传递的量子效率(ΦPSⅡ)和光化学猝灭系数(qP)下降的较少;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)诱导的活性较高,活性氧 (O(-)/()2、H2O2)和丙二醛(MDA)的产生积累较少,叶绿素和蛋白质含量下降较少,表现出耐光氧化特性,这与在自然条件下生育后期叶绿素含量变化相一致.相关分析表明它们的耐光氧化特性与结实率密切相关,说明耐光氧化品种抗早衰,有利籽粒充实.这些结果启示我们:从超高产育种出发,兼顾杂种优势利用和抗早衰两方面考虑,在母本不育系中引入粳型成分是一个值得重视的育种策略.     

超高产杂交稻剑叶衰老过程中的抗氧化性的变化

与对照种汕优63相比,超高产水稻组合培矮64S/E32的剑叶在生长后期具有更高的抗氧化酶(抗坏血酸过氧化物酶APX和谷胱甘肽还原酶GR)活性和小分子抗氧化剂(抗坏血酸Vc、总Vc、还原型谷胱甘肽GSH和β-胡萝卜素)含量,高的清除有机自由基DPPH·能力,更低的膜脂过氧化产物丙二醛含量。这表明培矮64S/E32剑叶在生长后期有强的抗氧化性,这种强抗氧化性与超高产水稻在结实后期剑叶中较慢的叶绿素和蛋白质降解速度相一致。     

自然条件下不同高产稻生育后期剑叶叶绿素荧光和膜脂过氧化的表现

以籼型 (OryzasativaL .)杂交组合汕优 6 3为对照 ,以中粳 95 16、两系亚种间杂交组合培矮 6 4S/E32、培矮6 4S/ 9311、亚种间三系杂交稻冈优 881和两系杂交组合X0 7S/紫恢 10 0为材料 ,研究其在生育后期 (抽穗 -成熟 )自然条件下剑叶的叶绿素衰减、CO2 交换、叶绿素荧光参数和膜脂过氧化表现。结果表明 :水稻在生育后期伴随叶绿素衰减 ,其叶内的原初光化学效率Fv/Fm、PSⅡ非环式电子传递效率ΦPSⅡ 、电子流传递速率ETR都有相应地下降 ,这种光能转化的障碍使多余的光能传递给PSⅡ的还原侧 ,产生O-·2 累积 ,发生膜脂过氧化和MDA的积累 ,引起光合色素及光合膜的破坏 ,发生光氧化早衰。这种现象在品种间有明显差异 ,耐光氧化的粳稻 95 16 ,其叶内的Fv/Fm、ΦPSⅡ 、ETR、qP下降较少 ,具有较稳定的光能转化能力 ,不易早衰 ,具有较高的结实率 ;而对光氧化敏感的籼稻汕优 6 3其叶内的Fv/Fm、ΦPSⅡ 、ETR ,光化学猝灭参数qP下降较多 ,易发生膜脂过氧化 ,导致叶片早衰 ,影响水稻灌浆结实和产量 ;而二系的和三系的杂交稻的耐光氧化特性和早衰表现居于中间。从水稻超高产育种的角度出发 ,在目前株型良好的基础上 ,兼顾杂种优势和防止早衰两方面考虑 ,在母本中利用粳型或带有粳型基因的不育系是育种上一个值得重     

超级杂交水稻谷粒产量与叶光合速率的关系

在2000～2005年期间,通过测定几种超级杂交水稻与普通杂交水稻‘汕优63’的产量构成和叶片光合作用探讨了谷粒产量与光合作用的关系。结果表明:(1)4种超级杂交水稻‘培矮64S/E32’、‘P88S/O293’、‘金23A/611’和‘GD-lS/ RB207’的产量水平显著高于‘汕优63’,是对照的108%～120%。(2)与‘汕优63’相比,这些超级杂交水稻的株型好,上层叶片直立,穗大即每穗粒数多,是对照的125%～177%。(3)与‘汕优63’相比,这些组合第二叶的净光合速率显著提高,但第一叶即剑叶的未必都较高。(4)去半叶处理降低了‘GD-1S/RB207’的结实率,而去半穗处理显著提高了结实率。因此,这些超级杂交水稻的高产原因在于穗大、株型好以及群体光能利用效率高。增加单叶特别是剑叶的光合能力是克服谷粒产量的光合产物源限制和在未来的超级杂交水稻育种中实现产量潜力新突破的关键。     

在光氧化条件下不同类型高产稻的叶绿素荧光特性和膜脂过氧化特点

用不同类型高产稻 (OryzasativaL .)粳稻 95 16、具有粳型成分的两系法亚种间杂交稻培矮 6 4/E32、两优培九(培矮 6 4/ 9311)和籼型杂交稻X0 7S/紫恢 10 0、冈优 881、汕优 6 3为材料 ,研究了孕穗期叶片在光氧化条件下的叶绿素荧光特性和膜脂过氧化表现。光氧化处理后 ,与籼型杂交稻比较 ,粳稻和具有粳型组分的亚种间杂交稻的PSⅡ原初光化学效率 (Fv/Fm)、PSⅡ的线性电子传递的量子效率 (ΦPSⅡ)和光化学猝灭系数 (qP)下降的较少 ;超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、过氧化物酶 (POD)诱导的活性较高 ,活性氧 (O-·2 、H2 O2 )和丙二醛 (MDA)的产生积累较少 ,叶绿素和蛋白质含量下降较少 ,表现出耐光氧化特性 ,这与在自然条件下生育后期叶绿素含量变化相一致。相关分析表明它们的耐光氧化特性与结实率密切相关 ,说明耐光氧化品种抗早衰 ,有利籽粒充实。这些结果启示我们 :从超高产育种出发 ,兼顾杂种优势利用和抗早衰两方面考虑 ,在母本不育系中引入粳型成分是一个值得重视的育种策略。     

高温下杂交稻培矮64S／E32与其亲本的光合和抗逆参数的比较

超级稻培矮64S／E32(F1)及其亲本(父本‘E32’和母本‘培矮64S’)的剑叶在不同温度(28、35、40℃ 和45℃)恒温水浴中保温1 h,随着处理温度的升高,F1除了较其亲本有更稳定的光合色素Chl外,还有明显 增加的Car／Chl,相对高的热稳蛋白含量,高而且稳定的总的抗氧化能力。F1在高温下也有较亲本高的光合 能力。高温下,线性电子传递过程比光化学过程对温度更敏感,F1有比亲本更敏感的调节机制,Pn下降比 ΦPSⅡ、Fv／Fm下降快说明光合限制步骤可能主要是位于光合碳同化而不是光化学和光合电子传递过程。     

Relationship Between PSⅡExcitation Pressure and Content of Super High-Yielding Hybrid Rice

The changes in photochemical features of PhotosystemⅡ(PSⅡ) and contents of Rubisco large subunit (RLS) and small subunit (RSS) in flag leaf from 75DAS to 113DAS (from filling to harvesting stages) were investigated in two hybrid rices (Oryza sativa L.) cv. Liangyoupeijiu and cv. Shanyou 63 grown in the field. Liangyoupeijiu is a super high-yielding rice and Shanyou 63 has widely been planted in China in these years. The results indicate that soluble protein and chlorophyll in both cultivars degraded slowly at first and dramatically thereafter. The degradation speed of soluble protein in Shanyou 63 was faster than that in Liangyoupeijiu. Both Fv/Fm and qP decreased in parallel with leaf senescence, whereas qN fell at first and then rose. No significant change in excitation pressure (1-qP ) was found before 89DAS but a sharply increase in both cultivars after it occurred. Excitation pressure rose more rapidly in Shanyou 63 than that in Liangyoupeijiu. The changes of RLS and RSS content exhibited the same trend as that of soluble protein content. A better linear correlation between RLS, RSS degradation and elevation of (1-qP ) were shown in both cultivars. We suggest that the increase in PSⅡ excitation pressure possibly induced the quick senescence process in rice flag leaf. The high-yielding of Liangyoupeijiu may be due to its maintenance of stronger photosynthetic capacity, longer and more stable photosynthetic functional du-ration than that of Shanyou 63.     

Photoinhibition and Photooxidation in Leaves of indica and  japonica Rice Under Different Temperatures and Light Intensities

Physiological indices related to the efficiency （ Fv/Fm ） of light energy conversion in PSⅡ and the peroxidation of membrane lipid were measured in leaves of Oryza sativa L. sp. indica rice cv. “Shanyou 63” and sp. japonica rice cv. “9516” under different temperatures and light intensities for 4 days. No changes in Fv/Fm and membrane lipid peroxidation product (MDA) were observed, so neither photoinhibition nor photooxidation happened in both rice cultivars under moderate temperature and medium light intensity. However, Fv/Fm dropped obviously with no change in MDA contents, and photoinhibition appeared in indica rice cv. “Shanyou 63” under medium temperature and strong light intensity. Furthermore, both photoinhibition and photooxidation were observed in two rice cultivars under chilling temperature and strong light intensity. Experiments with inhibitors under chilling temperature and strong light intensity showed that indica rice had a decrease in D1 protein content and SOD activity, and the extent of inhibition of xanthophyll cycle and nonphotochemical quenching ( qN ) was larger, and a higher level of MDA was observed. The photoinhibition and photooxidation in indica rice were more distinct as compared with japonica rice. The authors suggested that PSⅡ light energy conversion efficiency ( Fv/Fm ) and membrane lipid peroxidation were the key indices for the detection of photooxidation.     

Characteristics of Chlorophyll Fluorescence and Membrane-Lipid Peroxidation During Senescence of Flag Leaf in Different Cultivars of Rice

With japonica rice 98-08, indica hybrids Shanyou 63, Gangyou 881, and X07S/Zihui 100, and sub-species hybrid Peiai 64S/9311 as materials, chlorophyll (Chl) content, Chl a fluorescence parameters, and membrane lipid peroxidation in flag leaf were measured at late developmental stages under natural conditions. F_v/F_m, q_P, _PS2, and electron transport rate gradually decreased while q_N increased conversely. Excessive photon energy led to the accumulation of active oxygen (O₂ ^–), H₂O, malonyldialdehyde, and products of membrane lipid peroxidation, and resulted in reduced Chl content and early ageing subsequent to the photooxidation during flag leaf senescence. There was obvious diversification of these parameters among rice cultivars. In comparison with japonica cv. 98-08 (tolerant to photooxidation), F_v/F_m decreased in indica cv. Shanyou 63 (susceptible to photooxidation) with greater accumulation of active oxygen and a sharp drop in Chl content, which resulted in yellowish early ageing, and affected the filling and setting of rice grains. The mechanism for premature ageing in indica rice was related to irradiance and temperature at filling stages. On a sunny day at above 25 °C, the reaction centre of photosystem 2 (PS2) exhibited a dynamic change on reversible inactivation. Under the intense irradiance at noon, PS2 function in indica rice exhibited obvious down-regulation and photoinhibition. Under intense irradiance with lowered temperatures, PS2 resulted in photo-damage and early ageing, related to the degradation of PS2-D1 protein and the inhibition of endogenous protection systems such as the xanthophyll cycle and enzymes scavenging active oxygen. Hence for high-yield breeding, based on a good plant-type and utilising heterosis and tolerance of photooxidation, the selection of japonica rice or a sterile line with the japonica genotype as female is a strategy worthy of consideration.     

超高产杂交稻不同生育期的光合色素含量、净光合速率和水分利用效率

 较为系统地研究了两个超高产杂交稻‘两优培九’、‘华安3号’和多年来大面积推广的常规杂交稻‘汕优63’不同生育期的光合色素含量、净光合速率和水分利用效率。结果表明,在苗期,3个杂交稻的单位叶面积的叶绿素（Chl）含量差别不大,类胡萝卜素（Car）的含量以‘汕优63’为最高。然而,随着发育阶段的推进,到分蘖期,尤其是抽穗期剑叶的单位叶面积Chl和Car含量,两个超高产杂交稻高于‘汕优63’。从苗期到抽穗期,超高产杂交稻‘两优培九’和‘华安3号’的净光合速率（Pn）都比‘汕优63’高,而在苗期的午间强光条件下和分蘖期的早晨以及抽穗期的早晚相对弱光条件下其Pn的差别尤为显著。在苗期,‘汕优63’的水分利用效率（WUE）略高于‘两优培九’和‘华安3号’;到分蘖期和抽穗期,在上午10时之前和下午14时以后的时间段,则是两个超高产杂交稻明显高于‘汕优63’。这些结果说明,超高产杂交稻‘两优培九’和‘华安3号’不仅有较高的Pn和较强的抗光抑制能力,而且还能充分利用早晨和傍晚较弱的光强进行光合作用,这些是它们之所以高产的重要生理基础。此外,超高产杂交稻在生长发育的中后期（分蘖期和抽穗期）具有较高的WUE,有利于节约农业用水。     

Changes in Unsaturated Levels of Fatty Acids in Thylakoid PSⅡ Membrane Lipids During Chilling-induced Resistance in Rice

Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non-freezing temperature, as an inducer of "chilling resistance", was studied in three cultivars of rice (Oryza sativa L.), japonica cv. 9516 (j-9516), the two parental lines of superhigh-yield hybrid rice between subspecies,Peiai/E32 (ji-PE), and the traditional indica hybrid rice Shanyou 63 (i-SY63). Leaves of chill-treated rice showed chilling-induced resistance, as an increase of their low-temperature tolerance was measured using chlorophyll fluorescence measurements, revealing a change in photosystem Ⅱ (PSⅡ) efficiency. After 5 d of exposure to 11℃ under low light (100 μ mol·m-2·s-1), levels of unsaturated fatty acids in PSⅡ thylakoid membrane lipids decreased during the initial 1-2 d, then increased slowly and reached 99.2％, 95.3％ and 90.1％ of the initial value (0 d) in j-9516,ji-PE and i-SY63, respectively, on the fifth day. However, under medium light (600 μmol·m-2·s-1), all cultivars experienced similar substantial photoinhibition, which approached steady state levels after a decline in levels of unsaturated fatty acids in PSII thylakoid membrane lipids to about 57.1％, 53.8％ and 44.5％ of the initial values (0 d) in j-9516,ji-PE and i-SY63 on the fifth day. Under either chilling-induced resistance (the former) or low temperature photoinhibition (the latter) conditions, the changes of other physiological parameters such as D1 protein contents,electron transport activities of PSII (ETA), Fv/Fm, xanthophyl cycle activities expressed by DES (deepoxide state)were consistent with that of levels of unsaturated fatty acids in PSⅡ thylakoid membrane lipids. So there were negative correlations between saturated levels of fatty acids (16:1(3t), 16:0, 18:0), especially the 16:1(3t) fatty acid on thylakoid membrane and other physiological parameters, such as D1 protein contents, ETA and (A+Z)/(A+V+Z). A specific role of desaturation of fatty acids and the photoprotective pigments of the xanthophyl cycle, leading to an acclimation response in thylakoid membrane lipids may be involved. We conclude that chilling-induced resistance is accelerated by the unsaturation of thylakoid membranes, and the ability of rice plants to cold-harden can be enhanced by genetic engineering.