外源钙对干旱胁迫下甜菜幼苗生长的影响

为了解 Ca²⁺对干旱胁迫的缓解作用,对甜菜品种‘KWS1176’幼苗喷施 0、5、10、20 mmol/L 4 个CaCl₂水平溶液处理,测定对干旱胁迫下的甜菜幼苗生长、生理生化特性的影响。结果表明：(1)叶面喷施 CaCl₂溶液可有效缓解干旱胁迫对甜菜幼苗生长造成的损伤。其中,10 mmol/L CaCl₂溶液处理下甜菜幼苗株高受到的抑制最小,长势最好,与 0 mmol/L相比提高 41.24%。(2)Ca²⁺可缓解干旱胁迫对甜菜幼苗光合特性的抑制。叶面喷施 10 mmol/L CaCl₂溶液对幼苗叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间二氧化碳浓度(Ci)的缓解效果最佳,与 0 mmol/L相比,Pn、Tr、Gs分别提高70.62%、112.50%、67.00%,Ci 降低 32.77%。(3)干旱胁迫抑制了甜菜幼苗抗氧化酶活性,而 Ca²⁺可缓解其抑制作用。过氧化物酶(POD)和抗坏血酸过氧化物酶(AP...     

稀土元素钕对玉米幼苗根系抗旱性的影响

采用10%聚乙二醇6000模拟干旱胁迫,研究稀土元素钕对干旱胁迫下玉米幼苗根系抗旱性的影响。结果表明,干旱胁迫显著提高根系丙二醛(MDA)含量和过氧化氢(H_2O_2)含量,提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性,显著降低了过氧化物酶(POD)、谷胱苷肽转移酶(GST)、谷胱甘肽过氧化物酶(GPX)活性,显著降低抗坏血酸(As A)和谷胱苷肽(GSH)含量及根系生物量。干旱胁迫加剧了根系的氧化胁迫,玉米幼苗根系通过增强抗氧化酶活性抵抗干旱胁迫。外源氯化钕(NdCl_3)处理可显著提高干旱胁迫下玉米幼苗根系抗氧化酶SOD、POD、CAT、GST、GPX活性,显著提高AsA和GSH含量和根系生物量,显著降低MDA和H_2O_2含量,对APX活性无显著影响。盆栽实验结果进一步说明,NdCl_3对轻度和中度土壤干旱下玉米幼苗抗旱性均具有促进作用,对中度土壤干旱下玉米幼苗的抗旱性促进作用更佳。NdCl_3可提高玉米幼苗根系的抗旱能力,缓解干旱胁迫造成的伤害。     

亚精胺对盐胁迫下黄华占水稻幼苗根系抗氧化酶活性及Na+稳态的影响

以黄华占种子为材料，研究盐胁迫条件下，外源亚精胺(Spd)对水稻幼苗根系的生长、抗氧化酶活性、活性氧(ROS)代谢、丙二醛(MDA)以及Na⁺稳态的影响。结果表明，经100 mmol/L NaCl溶液处理水稻幼苗根系的ROS、·O₂^-、H₂O₂、Na⁺和MDA含量显著升高，过氧化物酶(POD)和过氧化氢酶(CAT)活性显著降低；在盐胁迫条件下，施用0.1 mmol/L Spd显著提高水稻幼苗根系的CAT和POD活性，显著降低ROS、·O₂^-、H₂O₂、Na⁺和MDA含量，从而减轻Na⁺毒害和过氧化造成的膜损伤，保护生物膜系统的稳定，维持细胞的稳态。     

外源 NO 对干旱胁迫下茶树生理特性的影响

研究外源 NO 对干旱胁迫生理生化反应。以15％聚乙二醇（PEG 6000）模拟干旱胁迫,0．5 mmol·L－1的外源 NO 供体（SNP）处理对茶树幼苗叶片游离脯氨酸、丙二醛（MDA）的含量及保护酶活性的影响。结果表明,一定浓度的 SNP 缓解干旱胁迫伤害的效果较好,显著提高了受干旱胁迫茶树幼苗叶片的保护酶（CAT）活性和游离脯氨酸含量,并降低了 MDA 的含量。表明外源 NO 通过提高干旱胁迫下渗透调节物质含量和保护酶活性,降低 MDA 的含量,缓解干旱胁迫对茶树幼苗的损伤,增强植株的抗旱性。     

水杨酸对干旱胁迫下小麦幼苗抗氧化特性的影响

为了给水杨酸在小麦栽培中的应用提供参考依据,以小麦品种百农AK58为材料,用17.5%聚乙二醇6000(PEG6000)模拟干旱胁迫,研究了外源水杨酸对干旱胁迫下小麦幼苗叶片和根系抗氧化特性的影响。结果表明,干旱胁迫显著提高了根、叶细胞质膜透性、丙二醛(MDA)含量及过氧化物岐化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)等抗氧化酶活性。与单独干旱胁迫处理相比,外源施加水杨酸可使干旱下小麦幼苗根系APX、POD、SOD和CAT活性分别增加190.9%、20.4%、42.3%和89.4%,使其膜透性和MDA含量分别降低19.7%和54.6%;对叶片而言,水杨酸可使其APX和POD活性分别增加31.5%和159.6%,使其膜透性和MDA含量分别降低23.7%和53.9%。上述结果说明,干旱胁迫加剧了小麦的氧化胁迫,小麦幼苗则通过增强根、叶抗氧化酶活性以抵抗氧化伤害。外源施加水杨酸可增强小麦幼苗根、叶相关抗氧化酶的活性,从而缓解小麦在干旱下所遭受的氧化伤害,增强其抗旱性。     

脱落酸对PEG胁迫下小麦幼苗渗透调节物质和抗氧化性的影响

为了明确脱落酸对PEG(聚乙二醇)胁迫下小麦幼苗渗透调节物质和抗氧化性的影响,筛选其有效增强小麦幼苗抗旱性的最适施用浓度,选用小麦品种洛旱6号为试验材料,采用室内水培法研究了在20%PEG胁迫下小麦幼苗经不同浓度脱落酸(ABA)处理后的形态及生理指标。结果表明:PEG胁迫下,外源ABA能够提高小麦幼苗可溶性糖、可溶性蛋白质和氨基酸含量,增强超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,降低超氧阴离子自由基■、过氧化氢(H_2O_2)含量,减少丙二醛(MDA)积累,促进小麦幼苗地上部生长。试验表明,外施ABA可通过提高小麦幼苗渗透调节能力和抗氧化酶活性来降低活性氧产生速率,减轻膜脂过氧化程度,维持细胞膜的稳定性,缓解PEG胁迫对小麦幼苗生长的抑制作用。本试验条件下以8 mg/L ABA效果最好。     

外源褪黑素对铬(Cr6+)胁迫下小麦幼苗光合特性和养分吸收的影响

为明确褪黑素对铬(Cr⁶⁺)胁迫下小麦幼苗光合和养分吸收的调节作用,在水培条件下以豫麦51(铬敏感型)和扬麦16(耐铬型)为材料,分析了Cr⁶⁺胁迫下外源褪黑素预处理(100μmmol·L^-1)后小麦幼苗光合和荧光参数及养分含量的变化。结果表明,Cr⁶⁺胁迫显著降低了小麦叶片叶绿素含量、气孔导度(G_s)和光系统Ⅱ(PSⅡ)活性,导致光合速率(P_n)显著降低;Cr⁶⁺胁迫也显著减弱了根系对营养元素(N、P、K、Mg、Fe和Mn)的吸收和转运。外源褪黑素处理显著提高了Cr⁶⁺胁迫下小麦幼苗的P_n、G_s、叶绿素(a和b)含量、实际光化学效率(Φ_PSⅡ)、最大光化学效率(F_v/F_m)、光化学淬灭(qL)和电子传递能力(ETR),增加了根系和叶片营养元素的含量。综合来看,外源褪黑素会促进Cr⁶⁺     

低温下外源水杨酸对玉米幼苗保护酶活性的影响

0.5mmol/L水杨酸(SA)预处理玉米幼苗降低了低温胁迫期间玉米幼苗体内丙二醛(MDA)的含量及超氧阴离子(O2-.)的产生速率。酶活性分析表明,SA预处理后玉米幼苗在低温胁迫下超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较低温对照高。常温下用0.5mmol/LSA预处理玉米幼苗,提高了保护酶的活性,从而提高了玉米幼苗的抗寒性。     

渗透胁迫下水杨酸诱导的小桐子甜菜碱积累涉及Ca2+/CaM信号

本研究以小桐子幼苗为材料,在水培条件下,研究了外源水杨酸（SA）对PEG 6000胁迫下小桐子幼苗甘氨酸甜菜碱含量、代谢关键酶BADH活性和相关基因表达,以及Ca²⁺和CaM抑制剂对SA诱导甜菜碱积累的影响。结果表明:外源1.5 mmol/L SA处理可显著提高渗透胁迫下小桐子幼苗的甜菜碱含量、增加甜菜碱合成关键酶BADH的活性,以及上调JcCMO和JcBADH的表达水平。与单独用PEG处理的幼苗相比,SA处理也提高了渗透胁迫下小桐子幼苗的钙调素（CaM）活性。此外,CaCl₂处理能增强SA诱导的甜菜碱积累效应,提高BADH的活性和上调JcBADH的表达水平,而Ca²⁺通道阻断剂 LaCl₃、CaM抑制剂CPZ和TFP处理得到相反的结果。这些结果表明,外源SA处理可提高渗透胁迫下小桐子幼苗甜菜碱的生物合成能力,且SA诱导的甜菜碱积累过程可能受到Ca²⁺/CaM信号的调控。     

外源MeJA对盐胁迫下玉米幼苗生长及抗氧化酶基因表达的影响

采用盆栽试验,以玉米品种CT505为材料,研究外源茉莉酸甲酯(MeJA)对盐(NaCl)胁迫下玉米幼苗生长及抗氧化酶基因表达的影响。结果表明,与对照相比,150 mmol/L的NaCl处理降低了玉米幼苗的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,减少了可溶性蛋白、可溶性糖和脯氨酸含量的积累,促进了丙二醛(MDA)含量和质膜透性的增加。添加1.0μmol/L MeJA在一定程度上可以缓解盐胁迫对玉米幼苗的损伤,与盐胁迫处理相比,玉米幼苗的SOD、POD和CAT活性分别增加了41.33%、26.09%和80.14%,可溶性蛋白、可溶性糖和脯氨酸含量分别上升了58.62%、12.20%和40.21%,相对电导率和MDA含量分别下降了9.29%和20.43%。外源MeJA能够提高盐胁迫下玉米幼苗的光合性能,与盐胁迫处理相比,其净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)显著增加,胞间二氧化碳浓度(Ci)下降,SOD3、POD3、CAT1这3种抗氧化酶基因表达量显著增加,表明外源茉莉酸甲酯能够有效缓解玉米的盐胁迫损伤。     

Physio-Biochemical Responses of Oil Palm (Elaeis guineensis Jacq.) Seedlings to Mannitol- and Polyethylene Glycol-Induced Iso-Osmotic Stresses

References

The aim of this investigation was to comparatively examine the physio-biochemical responses of oil palm seedlings to mannitol- and PEG-induced iso-osmotic stresses. The water content of osmotically stressed oil palm seedlings decreased, but the proline content and the electrolyte leakage of the seedlings increased with decreasing water potential (Ψ_w). However, the responses varied with the strength of osmotic stress and type of osmotic agent. Relative electrolyte leakage (REL) was negatively correlated to chlorophyll content in the osmotically stressed leaves. Chlorophyll a (Chl_a), chlorophyll b (Chl_b), total carotenoids (C_x+c) and total chlorophyll (TC) in the seedlings were significantly reduced by osmotic stress, subsequently reducing maximum quantum yield of PSII (F_v/F_m) and photon yield of PSII (Φ_psii), thereby lowering net-photosynthetic rate (P_n) and inhibiting growth. Physio-biochemical parameters, including REL, F_v/F_m, and Φ_psii in oil palm seedlings were reduced more greatly by PEG-induced osmotic stress than by mannitol-induced stress. A deterioration in morphological characters, including leaf chlorosis, leaf burn, and green leaf area reduction were demonstrated in oil palm seedlings under osmotic stress induced by either mannitol or PEG. However, the toxic symptoms in oil palm seedlings under PEG-induced stress were severer than in those under mannitol-induced iso-osmotic stress, especially under severe osmotic stress.     

Genotypic Diversity of Cross-Tolerance to Oxidative and Drought Stresses in Rice Seedlings Evaluated by the Maximum Quantum Yield of Photosystem II and Membrane Stability

Abstract

The genotypic variation of oxidative damage under oxidative and drought stresses was evaluated for a total of 67 rice cultivars consisting of 61 from the rice diversity research set of germplasm and 6 high-yielding varieties. The maximum quantum yield of photosystem II (F_v/F_m) and the membrane stability index (MSI) were measured to assess the oxidative damage induced by methyl viologen (MV) for oxidative stress and polyethylene glycol (PEG) for drought stress. Considerable variations in F_v/F_m and MSI among the cultivars in MV treatment indicated the existence of genotypic diversity in the susceptibility to oxidative damage. The weak relationships of F_v/F_m and MSI between MV and PEG treatment suggested that mechanisms other than oxidative stress tolerance affected the genotypic diversity of oxidative damage in PEG treatment. We used principal component analysis to quantify the cross-tolerance to oxidative damage under MV and PEG treatments: cross-tolerance was higher in cultivars in the japonica group than in the indica groups and higher in the improved cultivars than in the landraces. These results suggest that genotypic diversity of cross-tolerance is related to adaptation to the ecosystem where the genotypes originated and that the characteristics responsible for the tolerance to oxidative damage have been selected during breeding for improved grain yield.     

不同基因型玉米自交系苗期干旱-复水的生理响应机制

采用称重控水法模拟干旱胁迫,设对照和胁迫两个处理,在3叶期对24个玉米自交系叶片相对含水量(RWC)、游离脯氨酸(Pro)等生理指标进行测定,研究玉米的抗旱机理及复水补偿效应机制。结果表明,干旱胁迫下玉米叶片相对含水量、叶绿素荧光参数(F_v/F_m)和叶绿素含量(Chl)与对照相比显著下降,游离脯氨酸(Pro)、超氧化物歧化酶(SOD)和氧化物酶(POD)明显上升,复水后不同基因型自交系各生理指标表现出不同程度的补偿效应。利用隶属函数法将D17982、郑H71、PH4CV、昌7-2和L269等14份自交系归为抗旱性较强的自交系,PH4CV、HCL645、D17982、郑7314、郑H71和郑9712这6份自交系归为复水恢复能力强的自交系。     

亚精胺提高玉米幼苗抗寒性的研究

以玉米品种农大108为试验材料,当玉米幼苗2叶1心时,一部分在常温下(25℃/18℃)培养,另一部分在低温下(10℃/4℃)培养,以叶片喷施0.4 mmol/L亚精胺为处理组,喷施蒸馏水为对照组,研究亚精胺在玉米幼苗冷胁迫过程中的作用.结果表明,低温胁迫抑制了幼苗生长,加剧了叶片中超氧自由基和过氧化氢的产生,提高了膜脂...     

Effects of Coronatine on Growth,Gas Exchange Traits,Chlorophyll Content,Antioxidant Enzymes and Lipid Peroxidation in Maize (Zea mays L.) Seedlings under Simulated Drought Stress

Abstract

Coronatine is a phytotoxin that affects the accumulation of defence-related metabolites in plants but information on how its effects may be mediated by environmental stress is scanty. An experiment was carried out to determine the changes in growth, gas exchange, relative water content, chlorophyll (Chl) content, antioxidant enzymes and lipid peroxidation in maize (Zea mays L., var. ‘Nongda 3138’) seedlings treated with coronatine under simulated drought stress. Seedlings raised hydroponically in a growth chamber with simulated drought for 8d (long-period drought) or 3d (short-period drought) were treated with or without coronatine at the three-leaf stage. Under the drought condition, treated with coronatine significantly increased the fresh weight and relative water content in leaves of seedling leaves. The increase was accompanied by increased rates of photosynthesis and transpiration, and the maintenance of Chl pigments. Coronatine had no effects on catalase (CAT), guaiacol peroxidase (POD) and glutathione reductase (GR) under normal condition, but it significantly enhanced activities of CAT, POD and GR in stressed seedlings under the long-period drought treatment. Under the short-period drought treatment, the POD and GR activity in the seedlings treated with coronatine were much higher than in those not treated. Malondialdehyde (MDA) increased sharply under drought condition, but treatment with coronatine significantly reduced it by 15%. The total Chl content of leaves under the drought condition was markedly increased by the treatment with coronatine. Seedlings subjected to a short-period drought had reduced water content, but recovered fairly well by the treatment with coronatine with negligible effects on most physiological and biochemical processes. The application of coronatine alleviated the drought stress in maize seedlings and enhanced their tolerance of water stress through changes in physiological and anti-oxidant enzyme activities.     

玉米ZmGAPDH2基因的克隆及表达特性分析

研究通过同源比对查找GAPDH基因的保守区,运用逆转录PCR和同源克隆技术从玉米叶片中克隆出GAPDH2基因的全长cDNA序列。采用qRT-PCR分析两个玉米品种登海605和蠡玉35幼苗叶片中GAPDH2基因在非生物胁迫和ABA 处理下的表达特性,利用二维凝胶电泳（2-DE）和基质辅助激光解吸电离/飞行时间质谱法（MALDI-TOF）,对登海605和蠡玉35幼苗在干旱胁迫下叶片中的GAPDH蛋白表达水平进行分析。结果表明,ZmGAPDH2基因开放阅读框（ORF）全长1 014 bp,编码337个氨基酸。ZmGAPDH2蛋白分子量为36.53 kDa,属于亲水性蛋白。生物信息分析发现,玉米 ZmGAPDH2 蛋白和单子叶植物小米 GAPDH2 蛋白的亲缘关系最近,同源性高达94.66%。qRT-PCR分析表明,ZmGAPDH2在登海605和蠡玉35叶片中均能被ABA和PEG处理诱导表达,登海605在NaCl和蠡玉35幼苗在低温处理下其表达量均有所下降。干旱对登海605和蠡玉35幼苗叶片中ZmGAPDH2蛋白表达量也有影响。     

Correlation between Chloroplast Ultrastructure and Chlorophyll Fluorescence Characteristics in the Leaves of Rice (Oryza sativa L.) Grown under Salinity

Abstract

The seedlings of Oryza sativa L. cv. Nipponbare grown by hydroponic culture for 3 wks were treated with 75, 100, 150 and 200 mM NaCl for 14, 14, 6 and 3 days, respectively, and examined for chloroplast ultrastructure in the region where chlorophyll fluorescence had been recorded. NaCl treatment decreased the ratio of variable to maximum chlorophyll fluorescence yield (F_v/F_m) and caused swelling of thylakoids. The swelling of thylakoids was quantified by the percentage of the length of swollen thylakoids to the total length of thylakoids. This value was increased with increasing NaCl concentration. Although F_v/F_m decreased at all concentrations of NaCl, the minimal fluorescence yield F₀ was not increased by the treatment with 75 or 100 mM NaCl. The percentage of the length of swelling was low at 75 and 100 mM NaCl. On the other hand, F₀ increased and the swelling of thylakoids was prominent with 150 and 200 mM NaCl treatment. These results suggest that the decrease in F_v/F_m due to the increase in F₀ under salt stress correlates with the ultrastructural damage. The decrease in F_v/F_m due to the increase in F₀ is expected to be useful as an indicator to evaluate the damage in chloroplasts, especially in thylakoid membranes, under salinity.     

甜菜碱对玉米幼苗抗旱性的诱导效应

以旱玉5号和太单32为材料,在20%PEG模拟干旱条件下,研究外源甜菜碱对玉米幼苗抗旱性的诱导效应。结果表明,水分胁迫显著降低了玉米幼苗的生物量和叶片相对含水量,提高了幼苗的根冠比和渗透调节物质、抗氧化酶活性、ABA含量。喷施0.5mmol/L的甜菜碱溶液能缓解玉米幼苗的水分胁迫,提高幼苗的生物量、叶片相对含水量、根冠比及渗透调节物质、抗氧化酶活性、ABA含量。