黑穗醋栗叶片衰老过程中抗坏血酸含量及相关酶活性的变化特征

该试验以3个不同黑穗醋栗品种‘亚德’(Adelinia)、‘布劳德’(Brodtrop)和‘黑丰’(Heifeng)为材料,分析黑穗醋栗8个不同发育时期叶片(幼叶到衰老叶)中的抗坏血酸(AsA)含量、合成与代谢相关酶活性,以明确叶片生长发育及自然衰老过程中AsA含量与代谢合成相关酶之间的关系,为寻找黑穗醋栗最佳叶片采摘时期、AsA含量调控及延缓叶片衰老进程研究奠定基础。结果表明:(1)不同品种黑穗醋栗叶片中AsA含量和AsA相关代谢物水平存在明显的多样性;在叶片生长发育过程中,叶片总抗环血酸(T-AsA)和AsA含量在3个品种中变化趋势一致,均在成熟期叶中达到最高,其中‘亚德’成熟期叶片中AsA含量最高(98.33μmol/g),之后随着叶片的衰老而迅速下降,在衰老后期降至34.57μmol/g。(2)在叶片生长发育进程中,L-半乳糖途径中的关键酶L-半乳糖-1,4-内酯脱氢酶(GalLDH)活性变化与AsA含量变化趋势一致;AsA-GSH循环再生代谢中,脱氢抗坏血酸还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDHAR)、谷胱甘肽还原酶(GR)活性在展叶期最高,之后随着叶片的衰老而降至最低,这与AsA含量变化趋势相似,而抗坏血酸过氧化物酶(APX)活性变化与之正好相反;叶片H2O2含量则随着叶片的衰老逐渐增加,至衰老期达到最高。(3)GalLDH与T-AsA、AsA、氧化型抗坏血酸(DHA)、DHAR和MDHAR呈现极显著正相关关系,即叶片中GalLDH活性越高,叶片中AsA含量也越高;DHAR与T-AsA、AsA和DHA也存在极显著正相关关系。研究认为,黑穗醋栗叶片中AsA含量于成熟期达到最高,且品种间存在显著差异;GalLDH、DHAR可能是黑穗醋栗叶片AsA合成代谢的关键酶,可通过增强GalLDH和AsA-GSH循环系统相关酶活性来提高黑穗醋栗叶片中的AsA含量,进而延缓其衰老。     

烯效唑干拌种对小麦氮素积累和运转及籽粒蛋白质品质的影响

通过田间试验,研究了不同烯效唑干拌种剂量对3个不同筋力小麦品种植株氮素积累、运转和籽粒蛋白质品质的影响,结果表明,基因型、环境及烯效唑处理对小麦品质的影响效应依次减小,且均达到了极显著水平,但三者的互作效应较小。烯效唑处理后提高了不同生态点下不同小麦品种籽粒蛋白质含量和产量,处理后的面筋含量和沉淀值增加,面团形成时间和稳定时间延长;干拌种增加了开花期各营养器官中的氮素含量和单株氮素积累量,花后氮素总转移量、总转移率及其对籽粒氮的贡献率极显著提高,且处理后旗叶中可溶性蛋白质含量在花后15 d内均显著高于对照;对籽粒中氮含量而言,烯效唑处理后提高了灌浆初期籽粒中的非蛋白氮含量,花后5—20 d内均高于对照,灌浆期间籽粒蛋白氮含量均高于对照,因而处理后的粗蛋白质含量变化动态特点为谷底高、回升快。研究认为,烯效唑处理如同基因、环境一样独立影响小麦籽粒品质,而烯效唑处理后提高了开花初期旗叶中的可溶性蛋白质含量和花前营养器官中氮素含量及花后氮素转运量,可能是其提高籽粒非蛋白氮含量、促进籽粒蛋白质含量增加和蛋白质质量提高的重要原因之一,烯效唑干拌种对小麦籽粒蛋白质品质的改善具有广适性。     

麦秸翻压还田对隔茬冬小麦旗叶抗性的生理效应

为了揭示秸秆翻压还田对冬小麦旗叶叶片衰老及抗性指标的变化规律,试验设置4个小麦秸秆翻压还田量(0、4500、6000、7500kg/hm2),测定分析了冬小麦旗叶叶绿素含量、光合速率、丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性及可溶性蛋白质含量等抗性指标。结果表明,秸秆还田可明显减缓冬小麦植株衰老过程中叶片叶绿素的降解和光合速率下降,并有效调节叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)活性下降、可溶性蛋白质含量下降和丙二醛(MDA)含量的增加,延缓了冬小麦生育后期叶片的衰老;通过对各抗性指标与光合速率的相关性分析表明,各抗性指标在抑制冬小麦衰老过程中的作用大小依次为:丙二醛>可溶性蛋白质>POD活性>SOD的活性(丙二醛-0.999**;可溶性蛋白质0.997**;POD活性0.976*;SOD活性0.954*)。综合各处理的抗性指标得出,处理Ⅲ(6000kg/hm2)在提高作物后期抗逆性能力方面表现较好,处理Ⅳ(7500kg/hm2)表现较差。     

小麦Rubisco活化酶基因的克隆和表达特性

Rubisco活化酶是广泛存在于光合生物中调节Rubisco活性的酶,我们利用PCR技术,从小麦(Triticum aestivum)叶片cDNA文库中克隆得到Rubisco活化酶基因cDNA片段,该片段长度为850 bp,编码201个氨基酸.Northern blot表明,小麦叶片在暗诱导衰老的条件下,叶片中活化酶基因表达水平逐渐下降;同时,小麦叶片的光合特性、叶绿素含量和Rubisco活性呈现下降趋势.这些结果表明,衰老时小麦叶片Rubisco活化酶基因表达水平下降与光合速率下降密切相关.     

小麦Rubisco 活化酶基因的克隆和表达特性

Rubisco活化酶是广泛存在于光合生物中调节Rubisco活性的酶, 我们利用PCR技术, 从小麦(Triticum aestivum)叶片cDNA文库中克隆得到Rubisco活化酶基因cDNA片段, 该片段长度为850 bp, 编码201个氨基酸。Northern blot表明, 小麦叶片在暗诱导衰老的条件下, 叶片中活化酶基因表达水平逐渐下降; 同时, 小麦叶片的光合特性、叶绿素含量和Rubisco活性呈现下降趋势。这些结果表明, 衰老时小麦叶片Rubisco活化酶基因表达水平下降与光合速率下降密切相关。     

燕麦叶片衰老与活性氧代谢的关系

燕麦连体叶片与高体叶片衰老中,过氧化氢酶和超氧物歧化酶(SOD)活性下降,脂类过氧化产物丙二醛(MDA)迅速积累,组织自动氧化速率显著加快。植物激素BA,GA_3,2,4—D及光、亚胺环己酮(CH),EDTA处理均不同程度地延缓离体叶片的衰老过程,同时抑制过氧化氢酶和SOD活性下降,阻止MDA的积累和组织自动氧化速率的提高.推测叶片衰老中活性氧起着重要的作用。     

激动素和丁二酸拌种对玉米衰老过程中抗氧化系统和植物激素的影响

以‘郑单958’（晚衰型品种）和‘豫单2002’（早衰型品种）为实验材料,采用盆栽方式,0．03μg·kg-1的外源激动素（KT）和300mg·kg-1丁二酸复合剂进行拌种处理,研究拌种后玉米根叶衰老指标的变化及其化学调控效应。结果表明：激动素和丁二酸混合拌种后根系与叶片中超氧阴离子（O2-）产生速率、丙二醛（MDA）及脱落酸（ABA）含量低于其对照,而超氧化物歧化酶（SOD）活性和生长素（IAA）含量却较高,据此认为膜脂过氧化得到缓解,根叶的生理功能期延长;且在整个生育期内各个叶位叶的MDA含量、SOD活性、ABA和IAA含量高于根系,但其O2-和IAA／ABA较低,表明根系的衰老早于叶片。综上可以推测,激动素和丁二酸拌种能有效防止根叶早衰,为提高玉米产量打下基础。     

赤霉素和烯效唑对东北红豆杉紫杉醇代谢的影响

以一年生东北红豆杉扦插苗为材料,采用Hoagland营养液添加赤霉素及其合成抑制剂烯效唑的方法,研究了不同处理对东北红豆杉紫杉醇(taxol)及其前体巴卡亭Ⅲ(baccatinⅢ)与10-去乙酰基巴卡亭Ⅲ(10-DAB)含量变化的影响,同时比较了苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和超氧化物酶(SOD)活性变化,分析了紫杉醇合成旁路途径物质及抑制剂对紫杉醇代谢的作用效应.结果表明,不同浓度赤霉素(GA3)和烯效唑(S3307)处理对东北红豆杉POD、SOD及PAL活性的影响不显著;但整个处理过程中叶片中紫杉醇含量均为对照的1.28～6.44倍,茎中紫杉醇、baccatinⅢ及叶片中10-DAB含量在第6天均高于相应对照;赤霉素与烯效唑对紫杉醇及其前体合成的作用途径存在一致性.     

珍稀濒危植物珙桐过氧化物酶活性和丙二醛含量

采用比色法测定了不同年龄级、部位和叶位珙桐叶的过氧化物酶(POD)活性和丙二醛（MDA）含量,以探讨珙桐的生理生态适应性。结果表明：不同年龄级同一生长时期珙桐叶的POD活性和MDA含量不同,同年龄级同层的POD活性随叶位增大先升后降,MDA含量随叶位增大逐渐升高;同叶位不同层及同层不同叶位的珙桐叶的POD活性和MDA含量不同。珙桐叶POD活性和MDA含量对生长期敏感,同年龄级同叶位的珙桐叶随叶片的生长、衰老,POD活性和MDA含量逐渐升高,即珙桐叶POD活性和MDA含量受生物和非生物因子影响显著,且不同年龄级、叶位、层次存在差异。     

黄瓜叶片衰老过程中抗坏血酸含量与生理指标关系的研究

研究了黄瓜叶片衰老过程中抗坏血酸(ASA)含量及相关生理指标的变化,进一步分析了ASA与各相关生理指标之间的关系。结果显示,随着叶片逐渐衰老,丙二醛(MDA)含量、相对电导率(REC)及过氧化物酶(POD)活性显著升高;光合色素、可溶性蛋白质含量、超氧化物歧化酶(SOD)与过氧化氢酶(CAT)活性及ASA含量显著降低;ASA与MDA含量、REC、POD活性之间呈显著负相关关系,ASA与CAT及SOD活性之间呈显著正相关关系。研究表明,ASA对减缓叶片衰老有重要作用。     

杂交稻及其三系叶片衰老过程中SOD、CAT活性和MDA含量的变化

对杂交水稻及其三系主茎第11叶叶片自然衰老过程中超氧物歧化酶(SOD)、过氧化氢酶(CAT)和丙二醛(MDA)含量的变化进行了研究,结果表明:叶片衰老过程中,SOD和CAT活性下降,MDA的含量增加,可作为衰老特征的叶绿素和可溶性蛋白质含量明显下降;SOD的活性和MDA的含量变化相对应;CAT活性大幅度下降与SOD之间的不平衡,致使O_2~-代谢中间产物累积而引起膜的损伤。不育系的衰老进程比杂交水稻、恢复系和保持系慢,其SOD和CAT活性明显高于其它三者,可能是不育系不易早衰的原因之一。     

烯效唑（S-3307）对非洲菊切花保鲜的影响

以非洲菊(GerberajamesoniiBolus)切花为材料,以保鲜基本液(BP,20gL-1蔗糖 200mgL-1柠檬酸 150mgL-18-羟基喹啉柠檬酸盐)和添加30mgL-1烯效唑(S-3307)的基本液(BP S-3307)作对比实验,通过对切花外部形态观察和切花衰老过程中一些生理生化指标测定,探讨了S-3307对非洲菊切花的保鲜效果。结果表明,S-3307处理使切花的瓶插寿命比对照(蒸馏水)延长了4.3d,比BP处理延长了2.3d,而弯颈率分别仅为对照和BP处理的9.6%和28.8%。说明S-3307可增强切花的吸水能力,增加花枝的鲜重,延缓了切花花瓣中蛋白质的降解和抗氧化酶SOD和CAT活性的下降,并减少了游离脯氨酸和MDA的积累,维持膜结构的相对稳定性,从而延缓了非洲菊切花的衰老和提高了切花瓶插期间的观赏品质。     

Activities of chlorophyllase, phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase in the primary leaves of soybean during senescence and drought

The effects of senescence and drought on the levels and activities of chlorophyllase (EC 3.1.1.14), phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) and ribulose-1,5-bisphosphate carboxylase (Rubisco, EC 4.1.1.39) in the intact primary leaves of soybean ( Glycine max L. cv. Jackson) were monitored. Plants were grown either (1) for 2 to 8 weeks and the primary leaves harvested every week or (2) for 2 weeks and the plants subjected to drought stress and compared to control plants that were watered daily. In the senescence experiment, chlorophyllase activity changed in parallel with water content, leaf chlorophyll and total protein per unit dry weight of leaf tissue, with all factors increasing in concert during expansion of the primary leaves in the first 4 to 5 weeks of seedling development. Thereafter, all factors, including chlorophyllase activity, declined reaching markedly reduced values at weeks 7 and 8 when the primary leaves were yellow and ready to abscise. PEPC and Rubisco activities peaked in the third week, i.e. well before full leaf expansion, and then declined. In contrast to its response during senescence, chlorophyllase activity per unit leaf dry weight did not change during drought stress, but the specific activity of the enzyme rose and showed an inverse relationship to total leaf chlorophyll and protein content. Rubisco activity was highly sensitive to drought, with decrements observed in the activity and in levels of the large subunit within 2 days of withholding water and before significant changes in leaf water content were detected.     

Effects of S-3307, an Inhibitor of Gibberellin Biosynthesis, on Swelling of Leaf Sheath Cells and on the Arrangement of Cortical Microtubules in Onion Seedlings

Treatment with S-3307, a newly developed growth retardant, causedswelling of leaf sheaths in 2- to 3-leafed young onion seedlings(Allium ccpa L. cv. Senshu-Chuko), which otherwise showed noswelling even under long-day conditions. Before swelling becameevident, changes occurred in the arrangement of cortical microtubulesin leaf sheath cells of S-3307-treated seedlings. Cortical microtubulesin leaf sheath cells, which are normally oriented transverselyto the cell axis in untreated seedlings, were oriented longitudinallyor obliquely in treated seedlings. S-3307 exerted these effectsonly in seedlings grown under long-day conditions, but not undershort-day conditions. Simultaneously applied gibberellin reversed the effect of S-3307on swelling, indicating that S-3307 acts as an inhibitor ofgibberellin biosynthesis in onion seedlings. Endogenous gibberellinseems to play an important role in arranging cortical microtubulestransversely to the cell axis. (Received July 14, 1984; Accepted September 26, 1984)     

Superoxide Dismutase Activity and Lipid Peroxidation in Relation to Senescence of Rica Leaves

Superoxide dismutase (SOD), lipid peroxidation, ribulose 1, 5-bisphosphate earboxylasc and chlorophyll content in the leaves of rice were investigated during bloomJug to ripening stages. The results indicated that leaf senescence was associated with the decreascs of SOD and RuBP earboxylase activities and chlorophyll content. A marked increase of malondialdehyde(MDA)contcnt, a produet of lipid pcroxidation was observed during leaf senescence, However, the relative high activities of SOD and RuBP earboxylase and chlorophyll content, lower MDA content in hybrid rice senescenee leaves, compared with their three lines, suggest the presence of physiological hybrid vigor. The analysis of polyacrylamide gel eleetrophoresis showed that three SOD isozymes in leaf extract, which were Cu-Zn SOD. Changes of SOD isozymes were observed during leaf agling and at different time of storage of its extract. The destroying effect of oxygen free radical on enzymes and membrane in the course of leaf senescence was discussed.     

水稻叶片的衰老与超氧物歧化酶活性及脂质过氧化作用的关系

研究了从抽穗开花到籽粒成熟过程中,水稻植株顶部三片叶子的超氧物歧化酶(SOD),脂质过氧化产物丙二醛(MDA)含量及二磷酸核酮糖羧化酶活性的变化。实验结果表明:叶片的衰老伴随着 SOD 活性、RuBP 羧化酶活性及叶绿素含量的降低、丙二醛含量显著增高。分离了三个 SOD 的同工酶,证明为 Cu—Zn SOD。观察了 SOD 同工酶在叶片老化及酶液存放不同时间中的变化。讨论了叶片衰老过程中氧自由基对酶及质膜的损伤影响。     

Pyrophosphatase, Peroxidase and Polyphenoloxidase Activities during Leaf Development and Senescence

Inorganic pyrophosphatase, peroxidase, and polyphenoloxidase activities were studied as the function of leaf insertion level in eight monocotyledonous and eight dicotyledonous species. Alkaline inorganic pyrophosphatase shows a declining activity toward the end of senescence whereas no regular drift in either peroxidase or polyphenoloxidase activities was noticed during senescence of attached leaves. In the primary leaves of rice, peroxidase and polyphenoloxidase activities were high in the senescent leaves and there exists a correlation between chlorophyll content and peroxidase activity though not with polyphenoloxidase activity. Upon detachment leaves exhibit increasing peroxidase and polyphenoloxidase activities with time. The distribution of the enzyme activities during senescence of attached leaves is suggested to be species-specific, and an increase in peroxidase and polyphenoloxidase activities cannot be taken as an indicator of leaf senescence.     

Uniconazole (S-3307) strengthens the growth and cadmium accumulation of accumulator plant Malachium aquaticum

The effects of uniconazole (S-3307) application on the growth and cadmium (Cd) accumulation of accumulator plant Malachium aquaticum (L.) Fries. were studied through a pot experiment. The application of S-3307 increased the biomass and photosynthetic pigment content of M. aquaticum in Cd-contaminated soil, and also improved the superoxide dismutase (SOD) and peroxidase (POD) activities in M. aquaticum. Application of S-3307 increased Cd content in shoots and decreased Cd content in roots of M. aquaticum, but the translocation factor (TF) of M. aquaticum increased with the increase of S-3307 concentration. For phytoextraction, the application of S-3307 increased Cd extractions by roots, shoots and whole plants of M. aquaticum, and the maxima were obtained at 75 mg L^?1 S-3307, which increased by 22.07%, 37.79% and 29.07%, respectively, compared with their respective controls. Therefore, S-3307 can be used for enhancing the Cd extraction ability of M. aquaticum, and 75 mg L^?1 S-3307 was the optimal dose.     

Catalase, Peroxidase, and Polyphenoloxidase Activities during Rice Leaf Senescence

The activities of catalase, peroxidase, and polyphenoloxidase were studied in attached and detached rice (Oryza sativa L. cv. Ratna) leaves. Catalase activity decreased while peroxidase and polyphenoloxidase activities increased during senescence of both attached and detached rice leaves. Kinetic (5 mum) and benzimidazole (1 mm), which are known to delay the senescence of detached rice leaves, retarded the decrease of catalase activity during detached leaf senescence. On the other hand, these chemicals accelerated the increase of peroxidase and polyphenoloxidase activities over the water control. Total phenolics accumulated in detached and darkened rice leaves, but in attached leaf senescence in light no accumulation of phenolics was observed.     

砂仁不同叶位叶片的光合作用和氧化胁迫

衰老时砂仁叶片Pmax降低,这与叶片Gs、Chi含量和可溶性蛋白质含量的降低有关.随着叶片的衰老,NPQ、AQY、F/Fm、φPsIl和qp均降低,热耗散减少,光抑制加剧,衰老后期出现光破坏.但这些参数下降的幅度均小于Pmax下降幅度.光暗反应失衡,活性氧生成增加.衰老初期(老化)叶片MDA含量没有升高,衰老中后期叶片MDA含量显著升高,表明老化叶片能有效地耗散或清除活性氧,衰老叶片则不能,尽管其sOD、APX和POD等抗氧化酶活力显著升高.上述结果表明砂仁叶片老化与氧化胁迫关系不大,衰老与氧化胁迫密切相关.