淹水胁迫对不结球白菜根系生长与呼吸酶活性的影响

采用双套盆法,以不结球白菜‘新矮青’和‘新夏青2号’品种为材料,研究了不同时间(1、3、5、恢复7d后)和不同程度淹水处理(根淹、半淹)后不结球白菜根系生长及呼吸代谢的变化规律。结果显示:(1)与对照相比,淹水胁迫下,不结球白菜幼苗根系鲜重、根系长度、根系活力显著下降,且半淹处理的下降幅度大于根淹处理。(2)淹水胁迫下,乳酸脱氢酶(LDH)、乙醇脱氢酶(ADH)活性较对照显著升高,而苹果脱氢酶(MDH)、琥珀酸脱氢酶(SDH)活性显著降低,且半淹处理的降幅大于根淹,淹水5d后与淹水1d后有显著性差异。(3)淹水胁迫下,‘新矮青’乳酸发酵途径弱于‘新夏青2号’,乙醇发酵则相反,导致后者根系中乳酸积累多于前者,细胞质酸化较严重,降低了对淹水胁迫的耐性。研究表明,不结球白菜幼苗期受到淹水胁迫时,其有氧呼吸明显受阻,无氧呼吸代谢被促进,而且随着淹水时间的延长及淹水深度的加深,根系呼吸代谢受到的抑制程度越严重,最终导致根系生长受到抑制。     

低氧胁迫对黄瓜幼苗根系无氧呼吸酶和抗氧化酶活性的影响

对两个抗低氧胁迫能力不同的黄瓜品种进行营养液水培,研究了低氧胁迫下植株根系中无氧呼吸酶和抗氧化酶活性的变化。结果表明,低氧胁迫下,黄瓜植株生长受到抑制,鲜重和干重显著降低,根系中蛋白质含量降低,而根系中乳酸脱氢酶（LDH）、丙酮酸脱羧酶（PDC）、乙醇脱氢酶（ADH）、超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性在低氧胁迫下显著提高,且提高的幅度与品种抗低氧胁迫能力的强弱有关,与“中农8号”相比,抗低氧性胁迫能力较强的“绿霸春四号”根系内LDH活性增幅较小,而ADH、PDC、SOD、POD和CAT活性增幅较大。说明较高的ADH、PDC、SOD、POD、CAT活性和较低的LDH活性有利于增强幼苗植株抗低氧胁迫的能力。     

Ca2+对低氧胁迫下黄瓜幼苗生长和根系无氧呼吸酶的影响

采用营养液水培,以抗低氧能力不同的2个黄瓜品种为试材,研究了Ca2+对黄瓜幼苗植株生长和根系无氧呼吸酶活性的影响.结果表明,在低氧胁迫下,LDH、PDC和ADH活性提高程度与幼苗的抗低氧性和Ca2+浓度密切相关.与抗低氧性较弱的"中农8号"相比,抗低氧性强的"绿霸春4号"幼苗根系LDH活性增加缓慢,而PDC和ADH活性增加幅度较大,因此增强了植株对低氧胁迫的抗性.低氧胁迫下,营养液中8 mmol·L-1 Ca2+处理能显著提高根系ADH活性,降低LDH和PDC活性,0 mmol·L-1 Ca2+处理表现出相反的规律.由此可以说明,低氧胁迫下,Ca2+能够提高ADH活性,降低LDH和PDC活性,可增强黄瓜植株对低氧胁迫的抗性.     

微生物的无氧呼吸、发酵及其在生产和环境保护上的应用

阐述了生物氧化的含义、无氧呼吸、发酵在生产及环境保护上的应用。     

淹水对甜樱桃根系呼吸强度和呼吸酶活性的影响

以美早/东北山樱桃(Prunus serrulataG.Don)和美早/马哈利(P. mahaleb L.)为试材,研究了淹水对甜樱桃根系（生长根和褐色木质根）呼吸强度和呼吸酶活性的影响.结果表明：淹水过程中,两种甜樱桃砧木生长根和褐色木质根呼吸强度均呈下降趋势,生长根降幅更大;东北山樱桃生长根和褐色木质根呼吸强度降幅分别是马哈利的1.47和1.36倍.丙酮酸脱羧酶(PDC)、乳酸脱氢酶(LDH)活性在两类根系中均呈先升后降趋势,乙醇脱氢酶(ADH)活性在生长根中亦先升后降,而在褐色木质根中为上升趋势,3种酶活性变化幅度表现为生长根大于褐色木质根;东北山樱桃ADH和LDH活性增幅大于马哈利,但PDC活性则相反.两类根系苹果酸脱氢酶(MDH)活性均下降,且生长根降幅大于褐色木质根;东北山樱桃MDH活性降幅大于马哈利.说明生长根对淹水的敏感性强于褐色木质根;与马哈利相比,东北山樱桃对淹水更敏感.     

土壤紧实胁迫对黄瓜根系呼吸代谢的影响

用容重分别为1.20和1.55 g·cm^-3的土壤进行盆栽试验,研究了土壤紧实胁迫对‘津春4号’黄瓜根系呼吸代谢的影响.结果表明: 土壤紧实胁迫条件下,黄瓜根系中丙酮酸脱羧酶、乙醇脱氢酶和乳酸脱氢酶活性显著提高;无氧呼吸主要产物(乙醇、乙醛和乳酸)含量显著升高;参与有氧呼吸的苹果酸脱氢酶、琥珀酸脱氢酶和异柠檬酸脱氢酶活性显著下降,丙酮酸和琥珀酸含量显著提高,苹果酸含量显著下降.说明在土壤紧实胁迫条件下,黄瓜根系的有氧呼吸受到显著抑制,无氧呼吸过程加强.     

土壤紧实胁迫对黄瓜根系呼吸代谢的影响

用容重分别为1.20和1.55 g· cm-3的土壤进行盆栽试验,研究了土壤紧实胁迫对‘津春4号'黄瓜根系呼吸代谢的影响.结果表明:土壤紧实胁迫条件下,黄瓜根系中丙酮酸脱羧酶、乙醇脱氢酶和乳酸脱氢酶活性显著提高;无氧呼吸主要产物(乙醇、乙醛和乳酸)含量显著升高;参与有氧呼吸的苹果酸脱氢酶、琥珀酸脱氢酶和异柠檬酸脱氢酶活性显著下降,丙酮酸和琥珀酸含量显著提高,苹果酸含量显著下降.说明在土壤紧实胁迫条件下,黄瓜根系的有氧呼吸受到显著抑制,无氧呼吸过程加强.     

24-表油菜素内酯对低氧胁迫下黄瓜根系抗氧化系统及无氧呼吸酶活性的影响

用营养液水培,研究了根际低氧胁迫下24-表油菜素内酯(EBR)对2个抗低氧能力不同的黄瓜品种根系中抗氧化系统及无氧呼吸酶活性的影响。结果表明,在低氧胁迫下,EBR处理显著提高了低氧胁迫下2品种黄瓜幼苗根系SOD、POD及ADH活性,降低了O2-·、H2O2和MDA含量、LDH活性及‘中农八号’根系PDC活性,而对‘绿霸春四号’根系PDC及2个品种CAT活性无明显影响,表明外源EBR处理通过促进低氧胁迫下根系中抗氧化酶和ADH活性的提高,降低LDH活性及ROS含量,增强植株抗低氧胁迫的能力。     

硫化氢对淹水平邑甜茶根系形态构型、叶片活性氧和光合特性的影响

以盆栽平邑甜茶为试材,分别将盆浸没于5种浓度硫化氢(H₂S)释放剂硫氢化钠(NaHS;0、0.02、0.05、0.1、0.2 mmol·L^-1)水溶液,以及添加有次牛磺酸(HT;H₂S清除剂)的NaHS水溶液中,10 d后调查根系形态构型、叶片活性氧生成和光合气体交换参数以及植株生长的变化.结果表明: 在淹水处理液中加入0.02～0.1 mmol·L^-1 NaHS,能增加土壤淹水时根系总长度、表面积、体积、直径、根尖数、分形维数、一级侧根数量和根系活力,降低叶片超氧阴离子(O₂^-·)生成速率和过氧化氢(H₂O₂)含量,提高叶片光合速率(P_n)、蒸腾速率(T_r)、气孔导度(g_s)、水分利用效率(WUE)和表观CO₂利用效率(CUE),还提高幼苗株高和植株生物量,其中NaHS在浓度0.1 mmol·L^-1 时作用效果最显著;当NaHS施用浓度达到0.2 mmol·L^-1或在0.1 mmol·L^-1 NaHS中加施次牛磺酸时,上述指标均降回到单纯淹水时的水平.这说明添加适量H₂S能够有效缓解土壤淹水对平邑甜茶根系生长的抑制,可以通过减少活性氧产生以及提高CUE,从而减轻淹水胁迫对叶片光合性能和植株生长的不利影响.     

杂交稻汕优36幼苗根系呼吸代谢特点的研究

本文报道了对杂交水稻汕优36及其亲本幼苗根系生长、蛋白质含量、呼吸强度和G_6PDH、IDH、PK三种呼吸酶的初步研究。结果表明,杂种汕优36和其亲本相比,前者具有生长量高和呼吸强度低的特点。在呼吸代谢特点上,母本珍汕97A具有较高的IDH活力,父本IR36具有较高的G_6PDH活力。杂种汕优36PK活力高于双亲.但它在三种酶活力中所占比重与其它两种酶活力所占比重一样均居于双亲之间。作者认为,以PK活力为代表的EMP途径运转状况及EMP、TCA和HMP三条呼吸代谢途径之间的关系可能对杂交水稻幼根生长优势的形成起作重要作用。     

D-精氨酸对低氧胁迫下黄瓜幼苗根系多胺含量和无氧呼吸代谢的影响

采用营养液水培法,研究了根际低氧胁迫下D-精氨酸（D-Arg）对两个抗低氧能力不同的黄瓜品种根系中多胺含量和无氧呼吸代谢的影响.结果表明,低氧处理下,黄瓜幼苗根系中多胺含量显著增加,无氧呼吸代谢能力提高;与抗低氧能力弱的‘中农八号’相比,抗低氧能力强的‘绿霸春四号’根系中乙醇发酵活性较高,乳酸发酵活性较低;低氧胁迫下,D-精氨酸能显著降低黄瓜幼苗根系中腐胺、亚精胺和精胺含量,根系中乙醇脱氢酶（ADH）和乳酸脱氢酶（LDH）活性增加,乙醇和乳酸含量升高,植株生长受到抑制,而外源腐胺能缓解D-精氨酸的这种作用.说明黄瓜幼苗根系中较高的多胺含量可能有利于缓解低氧胁迫对植株造成的伤害.     

樱桃砧木叶片和叶柄再生体系的构建

以樱桃的两个砧木品种大青叶和大叶的组培苗为试材,通过5个激素因子的正交试验设计,建立了叶圆盘和叶柄片段的再生体系,研究出最佳愈伤组织形成和根苗分化的培养基,以提高组培快繁系数,并为基础转化提供技术保证。     

Regulatory O2 tensions for the synthesis of fermentation products in Escherichia coli and relation to aerobic respiration

In an oxystat, the synthesis of the fermentation products formate, acetate, ethanol, lactate, and succinate of Escherichia coli was studied as a function of the O₂ tension (pO₂) in the medium. The pO₂ values that gave rise to half-maximal synthesis of the products (pO_0.5) were 0.2–0.4 mbar for ethanol, acetate, and succinate, and 1 mbar for formate. The pO_0.5 for the expression of the adhE gene encoding alcohol dehydrogenase was approximately 0.8 mbar. Thus, the pO₂ for the onset of fermentation was distinctly lower than that for anaerobic respiration (pO_0.5≤ 5 mbar), which was determined earlier. An essential role for quinol oxidase bd in microaerobic growth was demonstrated. A mutant deficient for quinol oxidase bd produced lactate as a fermentation product during growth at microoxic conditions (approximately 10 mbar O₂), in contrast to the wild-type or a quinol-oxidase-bo-deficient strain. In the presence of nitrate, the amount of lactate was largely decreased. Therefore, under microoxic conditions, the pO₂ appears to be too high for (mixed acid) fermentation to function and too low for aerobic respiration by quinol oxidase bo. Received: 7 February 1997 / Accepted: 2 May 1997     

Combination of antagonistic yeasts with two food additives for control of brown rot caused by Monilinia fructicola on sweet cherry fruit

AIMS: To evaluate beneficial effect of two food additives, ammonium molybdate (NH4-Mo) and sodium bicarbonate (NaBi), on antagonistic yeasts for control of brown rot caused by Monilinia fructicola in sweet cherry fruit under various storage conditions. The mechanisms of action by which food additives enhance the efficacy of antagonistic yeasts were also evaluated. METHODS AND RESULTS: Biocontrol activity of Pichia membranefaciens and Cryptococcus laurentii against brown rot in sweet cherry fruit was improved by addition of 5 mmol l(-1) NH4-Mo or 2% NaBi when stored in air at 20 and 0 degrees C, and in controlled atmosphere (CA) storage with 10% O2 + 10% CO2 at 0 degrees C. Population dynamics of P. membranefaciens in the wounds of fruit were inhibited by NH4-Mo at 20 degrees C after 1 day of incubation and growth of C. laurentii was inhibited by NH4-Mo at 0 degrees C in CA storage after 60 days. In contrast, NaBi did not significantly influence growth of the two yeasts in fruit wounds under various storage conditions except that the growth of P. membranefaciens was stimulated after storage for 45 days at 0 degrees C in CA storage. When used alone, the two additives showed effective control of brown rot in sweet cherry fruit and the efficacy was closely correlated with the concentrations used. The result of in vitro indicated that growth of M. fructicola was significantly inhibited by NH4-Mo and NaBi. CONCLUSION: Application of additives improved biocontrol of brown rot on sweet cherry fruit under various storage conditions. It is postulated that the enhancement of disease control is directly because of the inhibitory effects of additives on pathogen growth, and indirectly because of the relatively little influence of additives on the growth of antagonistic yeasts. SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained in this study suggest that an integration of NH4-Mo or NaBi with biocontrol agents has great potential in commercial management of postharvest diseases of fruit.     

剥鳞和激素处理对大樱桃花芽休眠解除及内源激素变化的影响

采用高效液相色谱法(HPLC)分析了剥鳞与激素处理对大樱桃花芽休眠解除及内源生长素(IAA)、赤霉素(GAD、玉米素(ZT)和脱落酸(ABA)变化的影响。结果表明,花芽中的ABA主要分布于鳞片内,鳞片中的GA3和ZT含量远低于去鳞芽,也低于完整芽。剥鳞能明显增加休眠花芽中内源GA2和ZT的含量,降低ABA的含量,对IAA含量的影响不大。剥鳞降低了ABA／GA3、ABA／ZT的比值,使花芽向促进生长、抑制休眠的方向转化。同时,休眠前、后期剥鳞均能明显提高萌芽率,中期剥鳞效果不明显。剥鳞后施用外源激素随休眠时期不同而有不同的破眠效果,早期剥鳞GA3的效果最好,6-BA次之,IAA最差;中期破眠效果不如早期,GA。和6-BA没有明显差别;后期以6-BA效果最好,其次是GA3和IAA;3次处理中ABA均明显抑制花芽萌发。     

Scaling of respiration to nitrogen in leaves, stems and roots of higher land plants

Using a database of 2510 measurements from 287 species, we assessed whether general relationships exist between mass-based dark respiration rate and nitrogen concentration for stems and roots, and if they do, whether they are similar to those for leaves. The results demonstrate strong respiration–nitrogen scaling relationships for all observations and for data averaged by species; for roots, stems and leaves examined separately; and for life-forms (woody, herbaceous plants) and phylogenetic groups (angiosperms, gymnosperms) considered separately. No consistent differences in the slopes of these log–log scaling relations were observed among organs or among plant groups, but respiration rates at any common nitrogen concentration were consistently lower on average in leaves than in stems or roots, indicating that organ-specific relationships should be used in models that simulate respiration based on tissue nitrogen concentrations. The results demonstrate both common and divergent aspects of tissue-level respiration–nitrogen scaling for leaves, stems and roots across higher land plants, which are important in their own right and for their utility in modelling carbon fluxes at local to global scales.     

氧化还原电位对Actinobacillus succinogenes厌氧发酵生产丁二酸的影响

为提高琥珀酸放线菌Actinobacillus succinogenes CGMCC1593厌氧发酵产丁二酸的水平。研究了以葡萄糖为C源,发酵液中不同氧化还原电位（VORP）对A．succirtogenes CGMCC1593生长和代谢产物分布的影响。结果表明：菌体生长和丁二酸积累的较佳VORP分别为-220mV和-270mV;利用代谢流分析法,比较VORP在-220mV和-270mV时发酵对数生长期（8h）和稳定期（20h）的代谢通量分布,以及发酵过程中磷酸烯醇式丙酮酸（PEP）、丙酮酸（Pyr）节点,NADH通量分配的变化,由此得出在VORP为-270mV时,NADH总通量和丁二酸方向代谢通量增幅明显。在发酵过程中,通过降低VORP至-270mV,使丁二酸的产率从70％提高到85％。     

添加剂对水稻秸秆实地混合厌氧发酵产甲烷系统的作用

为提高水稻秸秆利用效率,改进水稻秸秆实地混合厌氧发酵产甲烷技术,本研究开展了添加剂在混合厌氧发酵系统的应用研究。试验选取水稻秸秆和猪粪作为发酵原料,通过分别添加不同的浓度的吐温20和腐植酸,测定甲烷的产气量和浓度、秸秆的降解和土壤肥力的变化,以揭示添加剂类型及其浓度对水稻田实地甲烷生产系统的影响。结果表明:添加剂的掺入并未影响产气的动态变化趋势,但显著地促进产气和提高产气浓度,整体效果由高到低为腐植酸吐温20对照,其中经腐植酸处理的产气量和产气浓度对照相比分别提高了50. 73%和24. 55%。添加剂的掺入有利于水稻秸秆纤维素和半纤维素的降解,但对木质素没有显著影响;其中以0. 15 g/L腐植酸和0. 30 g/L吐温20的降解率最高,相较于对照其纤维素降解率均提高了22. 11%,半纤维素降解率分别提高了107. 13%和98. 39%。添加剂的掺入能显著增加土壤肥力,以0. 15 g/L腐植酸和0. 30 g/L吐温20处理水平的效果最优,相较于对照,其土壤有机质分别增加了29. 63%和23. 72%,全氮分别增加了52. 32%和42. 38%,全磷分别增加了83. 33%和57. 14%。     

Influence of exogenous ethylene on ipomeamarone accumulation in black rot infected sweet potato roots

Ipomeamarone accumulation in sweet potato (Ipomoea batatas) roots infected with Ceratocystis fimbriata (black rot) was decreased by one-third when roots were stored under 100 ppm ethylene. This effect of ethylene was not observed when infected tissue was also treated with benzylisothiocyanate. Ethylene treatment and long term infection were associated with the accumulation of 4-ipomeanol and 1-ipomeanol.     

Structural differences in full-length cDNAs for two classes of sporamin,the major soluble protein of sweet potato tuberous roots

Summary Sporamin, which accounts for 80% of the total soluble proteins in sweet potato tuberous roots, consists of two polypeptide classes, A and B. The sporamin cDNA clones can also be classified into sporamin A and B subfamilies based on their sequence homologies, with intra-subfamily homologies being much higher than inter-subfamily homologies. The sequence of an essentially full-length cDNA for sporamin B was compared with that for sporamin A. The coding sequences of two cDNAs share 83% sequence homology. The sequences in the 5- and 3-noncoding regions show many deletions in addition to base substitutions. The endpoints of deletions longer than 4 bp match precisely to the endpoints of short direct repeats present in the other sequence, which suggests that these deletions are generated by slipped mispairing during DNA replication. In the 5- and 3-noncoding region of sporamin B cDNA, there are 5 bp direct repeats with sequences complementary to each other. Since most of these repeats are absent in sporamin A cDNA, these structural features may cause a difference in the secondary structure between A and B mRNAs and affect the translational efficiencies or stabilities of the mRNAs. Precursors for both classes of sporamin carry N-terminal extra-sequences which can be separated into a putative signal peptide segment and a segment enriched with basic amino acids. A two-step processing mechanism for the maturation of sporamin is suggested.