大豆种子吸胀冷害抗性与其质体膜脂不饱和度正相关

吸胀冷害是干种子在吸胀阶段遭受低温造成不萌发的现象,结果可能造成农作物损失严重。虽然吸胀过程中细胞膜的修复是关键事件,而且细胞膜在响应水分和温度胁迫中扮演重要角色,但是种子吸胀过程中膜变化的过程,特别是膜流动性变化过程研究较少。本文比较了吸胀冷害耐受型（LX）和敏感型（R5）两个大豆品种在吸胀冷害过程中膜脂不饱和度（double bond index, DBI）的变化,结果发现,LX和R5在常温（25℃）吸胀时变化趋势一致,质体膜脂DBI升高,质体外膜脂中磷脂酰甘油(phosphatidylglycerol, PG)分子DBI下降。LX和R5在低温（4℃）吸胀时DBI变化有很大差异,低温吸胀仅仅延缓了耐受型LX中质体膜脂DBI的升高,但是敏感性R5质体膜脂DBI不仅没有升高反而下降。用浓度33%的聚乙二醇 (polyethylene glycol, PEG)引发没有直接引起DBI变化,但是所引起的细微而显著的变化可能为萌发做好准备。PEG引发处理后的R5在吸胀冷害后第二和第三阶段质体膜脂DBI迅速增加,这个增加模式与LX的DBI增加相似。结果表明,吸胀冷害延缓或者阻滞了质体膜脂不饱和度的升高,大豆种子的吸胀冷害抗性与质体膜脂不饱和度正相关,提高质体膜质DBI可以提高吸胀冷害抗性。     

提高杂交稻种子活力和抗吸胀冷害的研究（简报）

杂交水稻种子对低温吸胀冷害比较敏感,尤以低活力的陈种子更为突出。通过PEG引发或吸湿回干等“渗控”预处理可以达到有效减轻吸胀冷害起到预防的效果。     

渗透调节对低温伤害敏感大豆种子质膜氧化还原活性的影响

选用对吸胀冷害敏感的大豆[Glycine max(L.)Merr.]品种"黑河23"种子为试材,研究了渗透调节增强大豆种子活力过程中种子质膜氧化还原活性的变化.结果表明,大豆种子活力指数与种子质膜氧化还原活性呈正相关.与对照相比,渗控12 h显著提高大豆种子活力,表现在发芽指数、活力指数和TF生成量的提高,种子质膜NADH和NADPH氧化速率及Fe(CN)63-和EDTA-Fe3 还原速率明显上升;随着引发时间的延长,种子活力上升变缓,种子质膜NADH和NADPH氧化速率及Fe(CN)63-还原速率上升速度变慢,EDTA-Fe3 的还原速率在渗控24 h后开始下降,但渗控72 h仍高于对照.     

渗透调节增强大豆种子活力

选用对吸胀冷害敏感的大豆 [Glycine max(L.)Merr.]品种‘黑河23‘为试材,系统研究了渗控增强种子活力的机理.结果表明,与对照相比,渗控12 h显著提高种子抗吸胀冷害的能力,并且随着渗控时间的延长逐渐增强,表现在种子渗漏物减少,渗漏物中K /Na 比降低,冷浸对活力指数的负效应减小.水苏糖、蔗糖的含量在12 h达最大值,以后呈缓慢下降趋势,而葡萄糖、果糖含量在渗控后期开始上升.过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)等抗氧化酶的活性在整个渗控过程中都有不同程度的增强,丙二醛(MDA)含量减少.表明渗控可提供一个合适的渗透压,使种子在适度的渗透压下启动萌发过程.研究还揭示22℃渗控效果优于4℃.     

萝卜颗粒引发大豆种子抗吸胀冷害能力的效应

以鲜萝卜颗粒和聚乙二醇(PEG)引发大豆种子抗吸胀冷害能力的研究结果表明,二者都能引发和控制种子在低温吸胀过程中的吸水,提高种子活力和萌发率,减少细胞中电解质和氨基酸外渗。     

花生种子萌发吸胀阶段冷害抗性的鉴定及耐冷种质的筛选

为更好地评价花生吸胀冷害抗性,本研究首先分析了常温条件下(25℃)和冷胁迫条件下(2℃)花生种子萌发过程中的吸水状况,结果表明不同基因型的花生吸胀阶段的持续时间基本一致,维持在浸种后0～12 h;冷胁迫能够使吸胀阶段初期的吸水速度显著下降,但对吸胀阶段的持续时间没有显著影响。对种子萌发3个生理阶段(吸胀、萌动、萌发阶段)分别进行冷害胁迫处理,结果表明吸胀阶段遭受的冷害胁迫对花生种子萌发影响较其他阶段严重。进一步的试验表明,吸胀阶段种子2℃冷胁迫12 h,能够更好地区分不同花生种质之间吸胀冷害抗性的差异,从而建立了花生种子吸胀冷害抗性的鉴定体系。利用该鉴定体系对64份花生种质的吸胀冷害抗性进行鉴定,以相对发芽率85%为阈值,筛选出了7份耐冷种质。本研究为花生耐冷育种及吸胀冷害抗性机制解析提供了技术鉴定体系和材料基础。     

聚乙二醇(PEG)引发预防大豆种子吸胀冷害的效果

PEG引发法是一种预防敏感大豆种子吸胀冷害的有效方法。我们首次发现引发种子能抗御长达2个月的2～3℃低温而不降低种子活力,由之发育的幼苗其离体子叶在普通滤纸发芽床上形成愈伤组织并有再分化现象。引发过程中种子呼吸强度逐渐提高,推测PEG引发提高抗性的作用与种子代谢活动的预先启动有关。     

一氧化氮对番茄种子抗吸胀冷害的影响

以番茄毛粉802种子为材料,通过对比实验,测定分析各处理种子的萌发率及第4天的平均根长、萌发指数、活力指数,以及相对电导率(REC)、丙二醛(MDA)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)含量的变化,以探讨NO对番茄种子吸胀冷害的抵抗作用及其机理.结果显示:(1)外源NO可显著提高番茄种子经12 h吸胀冷害处理后的萌发率、平均根长、萌发指数和活力指数,并显著降低吸胀冷害下REC和MDA含量,同时显著提高SOD和CAT的含量.(2)NO所提高的吸胀冷害处理后种子的SOD和CAT活性不能被RNA合成抑制剂放线菌素D和蛋白质合成抑制剂环己酰亚胺抑制.结果表明,NO可提高番茄种子抵抗吸胀冷害的能力,而且与NO激活了抗氧化系统有关,但NO不是通过促进抗氧化酶的合成来提高其活性.     

干旱对大豆线粒体膜脂的磷脂和脂肪酸组分的影响

干旱胁迫致使大豆叶片线粒体膜脂的PG摩尔百分含量降低,而LPC,PC,PI,PE,PA则明显提高。抗旱品种和敏感品种之间棕榈酸及亚麻酸含量有明显差异,且抗旱品种叶片线粒体膜脂的总脂肪酸不饱和指数低于敏感品种。     

低能离子注入对大豆种子吸胀冷害的影响

本文分别从浸种液中无机离子的浓度、可溶性糖的浓度以及溶液的pH值,研究了低能离子注入对大豆种子吸胀冷害的影响。结果发现一定剂量的氮离子注入大豆种子后,其无机离子、可溶性糖、酸性物质的泄漏量均有低于对照组的趋势,而且其长势好于对照组,说明离子注入能在一定程度上减轻大豆遭受的吸胀冷害。     

Osmopriming-Regulated Changes of Plasma Membrane Composition and Function were Inhibited by Phenylarsine Oxide in Soybean Seeds

The aim of the present work was to investigate the effects of osmoconditioning on chilling injury in chilling-sensitive soybean ( Glycine max (L.) Merr. Zhonghuang No. 22) seeds during imbibition. Low temperatures reduced the germination rate and no seed germinated at 1 °C. Osmoconditioning of seeds at 20 °C with a polyethylene glycol-8000 (PEG8000) solution at 1.5 MPa for 72 h followed by drying back to their initial moisture content (MC) reduced their chilling sensitivity. The phenylarsine oxide (PAO), an inhibitor of protein tyrosinephosphatases, was used to investigate the possible involvement of phosphorylation-dephosphorylation of Tyr residues in the plasma membrane composition and function when seeds were osmoconditioned. The results showed the germination of osmoconditioned seeds decreased significantly when PAO was added in PEG solution after chilling treatment. PAO inhibited changes in composition of plasma membrane phospholipids and fatty acid induced by osmocondition, indicated that tyrosine protein phosphorylation is involved in the regulatory mechanisms of osmocondition-responsive chilling in soybean seeds. Western blot result further indicated that osmocondition treatment improved the activity of plasma membrane H⁺-ATPase after chilling treatment, but this effect was abolished by PAO. The possible regulation mechanism by Tyr protein phosphorylation is discussed.     

Composition and positional distribution of fatty acids in polar lipids from Chlorella ellipsoidea differing in chilling susceptibility and frost hardiness

The composition and positional distribution of fatty acids in the polar lipids from 4 strains of Chlorella differing in chilling susceptibility and frost hardiness were analyzed by enzymatic hydrolysis and gas-liquid chromatography. Analysis of the polar lipids from chilling-sensitive, chilling-resistant and chilling-sensitive revertant strains of Chlorella ellipsoidea IAM C-102 showed that the sum of palmitic and trans -3-hexadecenoic acid in phosphatidylglycerol (PG) is about 60% for the sensitive strains and 53% for the resistant strain. The sum of dipalmitoyl and 1-palmitoyl-2-( trans -3-hexadecenoyl) PG as estimated from the positional distribution of their fatty acids, is about 10% in the case of each of the three strains. The contents of unsaturated fatty acids in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were higher in the resistant than in the sensitive strain. This suggests that unsaturation of fatty acids in not only PG but also PC and PE is involved in chilling sensitivity of Chlorella . On the other hand, lipid changes during the development of frost hardiness of C. ellipsoidea IAM C-27, a frost hardy strain, were examined. The results showed that fatty acids in most lipid classes are unsaturated in the hardening process but their degree of unsaturation is not greatly different from that of the chilling-resistant strain, suggesting that not only unsaturation of fatty acids in lipids but also other factors are necessary for the development of frost hardiness.     

Fatty Acid Distribution in Glycolipids and Phospholipids in Cotyledons of Germinating Soybeans

This investigation was conducted to observe changes in the fatty acid distributions of glycolipids (GL) and phospholipids (PL) in cotyledons of soybean seeds which were germinated either in the dark or the light at 28°C for 8 days. The GL isolated from the total lipids of cotyledons at different germinating stages were : acyl sterylglycoside (ASG), monogalactosyl diglyceride (MGD), digalactosyl diglyceride (DGD) and sulfolipid (SL). The PL isolated from the same total lipids as described above were : diphosphatidyl glycerol (DPG), phosphatidic acid (PA), phosphatidyl ethanolamine (PE), phosphatidyl glycerol (PG), phosphatidyl choline (PC) and phosphatidyl inositol (PI).

During germination of soybean seeds, the content of linoleic and linolenic acids in MGD or DGD was markedly higher than that of the other GL. The positional distribution of fatty acids in PE, PC and PI was shown in all PL, in which saturated fatty acids, especially palmitic acid, were highly concentrated in position 1 and unsaturated fatty acids, especially linoleic acid, mainly occupied position 2. A remarkable difference in the changing patterns of fatty acid composition, which depended on the germinating conditions tested, was observed between GL and PL. The changes in fatty acid composition of GL were more marked in the light-grown seedlings than in the dark-grown, whereas those of PL were more remarkable in the latter than in the former. Therefore, the positional distribution of fatty acids in PL was more evident in the light-grown seedlings than in the dark-grown ones.

These results suggest the metabolic fate of GL and PL in cotyledons of soybean seeds, probably owing to the differences in the two germinating conditions tested.     

Hydrogen Peroxide Sensor System Using Immobilized Luminous Bacterium

The mitochondria were prepared from apples cv. Starking Delicious which were sensitive to chilling injury and apples cv. Rails Janet which were not sensitive to chilling injury. The content of unsaturated fatty acids in the Rails Janet mitochondria was higher than that in the Starking Delicious mitochondria. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidic acid, phosphatidylserine, diphosphatidylglycerol (cardiolipin) and mono- and digalactosyldiglyceride were identified as the conjugated lipid components. The PC/PE ratios were 0.74 and 0.14, respectively, in the mitochondrial phospholipid fraction of Rails Janet and Starking Delicious apples. The higher ratio of PC/PE and unsaturated fatty acid contents in Rails Janet than those in Starking Delicious may cause the resistance to chilling injury in Rails Janet by playing a role in lowering of the phase transition temperature. These facts were thought to contribute largely to the flexibility, fluidity and the function of transport of the membranes in the cold state.     

Physiological Effects of Hydration-Dehydration Treatment on Soybean Seeds to Enhance Its Resistance to Imbibitional Chilling Injury

The soybean (Glycine max Merrill) cv. “Heihe No. 3” which is sensitive to imbibitional chilling injury was used as experimental material. From the point of cell membranes and by means of physiological tests, the relation of hydration-dehydration to membrane repairation during rehydration in seeds was discussed, and a new point of view on the acting mechanisms of hydration-dehydration was approached. The resistance of seed to imbibitional chilling injury was obviouslv enhanced, its apparent efficiency displayed the enhance of seed rigor, reduction of leakage, especially the K+/Na+ ratio; increasing the K+-Na+-ATPase activity,. The facts indicate that the function of cytoplasmic membrane was enhanced and maintained normally. In the meantime, the activities of SOD, catalase and peroxidase were all enhanced, and the production of volatile aldehydes were decreased. It shows that the function of cell antiautoxidation system was greatly improved. Based on a series of physiological and biochemical index mentioned above and the comparison of water-absorbed curves, a postulated model of membrane system induced by hydration-dehydration treatment is given. It is considered that the effects of the two processes, i,e. physical membrane repairation as well as the physiological and biochemical repairation, will be persisted in the redehydrated seeds.     

Plasma membrane phospholipid and sterol synthesis in soybean hypocotyl segments undergoing auxin-induced elongation

Summary Auxin-induced cell elongation necessitates plasma membrane enlargement. The effect of auxin (10 M 2,4-dichlorophenoxyacetic acid) treatment on amount, composition, and rate of synthesis of plasma membrane lipids was examined. Auxin-treated and control soybean (Glycine max L.) hypocotyl segments were incubated with [¹⁴C]acetate for times ranging from 0.5 to 18 h, prior to isolation of plasma membrane by aqueous two-phase partitioning. The composition of individual plasma membrane lipids in elongating segments did not differ from the composition in treatment time-matched control segments, except that after longer auxin treatments, phospholipids had more unsaturated fatty acids. Plasma membrane phospholipid and free sterol content both increased in elongating segments. The relative proportion of sterols and phospholipids in the plasma membrane primarily depended on time after segment excision, for both auxin-treated and control segments. Auxin enhanced the rate of lipid incorporation into the plasma membrane by 6 h, and stimulated the synthesis of some phospholipids and sterols.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - ER endoplasmic reticulum - GC gas chromatography - IAA indole-3-acetic acid - PA phosphatidic acid - PC phosphatidylcholine - PE phosphatidylethanolamine - PG phosphatidylglycerol - PI phosphatidylinositol - PM plasma membrane - PS phosphatidylserine     

The relationship between plasma membrane lipid composition and physical-chemical properties. III. Detailed physical and biochemical analysis of fatty acid-substituted EL4 plasma membranes

Murine leukemia EL4 cells were modified by supplementation of culture media with fatty acids for 24 h. A plasma membrane-enriched fraction was prepared from substituted and normal cells. Analyses were performed to determine fatty acyl composition, phospholipid headgroup composition and cholesterol content. The two major membrane phospholipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC) were isolated by thin-layer chromatography and ESR measurements were done on liposomes prepared from these lipids as well as on the intact plasma membrane preparations. Slight perturbations in overall plasma membrane lipid composition were observed when EL4 cells were supplemented with a single exogenous fatty acid. This may be consistent with the idea that the incorporation of exogenous fatty acid induces compensatory changes in membrane lipid composition. On the other hand, we observed no significant difference in two ESR motional parameters between the unsubstituted control and various fatty acid-substituted plasma membranes. ESR measurements carried out on PE and PC liposomes derived from 17:0- and 18:2c-substituted membranes also failed to detect major differences between these liposomes and those made from normal EL4 phospholipids. In the case of liposomes prepared from 18:2t,-substituted membranes, the order parameter was significantly changed from the normal. However, the change was in opposite directions in PE and PC, perhaps accounting for the fact that no change parameter is seen in intact 18:2t-substituted plasma membrane. Measurements of order parameter (S) in mixed lipid vesicles showed that at up to 50 mol% mixture of a synthetic PC with plasma membrane PC, the value of S was only marginally different from that of the plasma membrane PC vesicles. We interpret these data as an indication that the two ESR parameters used are not sufficiently sensitive to detect changes due to modifications of the acyl chain composition of a complex biological membrane.     

The effect of the temperature of drying on viability and some factors affecting storability of <Emphasis Type="Italic">Fagus sylvatica</Emphasis> seeds

Beech (Fagus sylvatica L.) seeds, which are tolerant to desiccation, freshly harvested after shedding, were dried at 15 and 30 °C and at the similar rate, to 9% of water content. A slight decrease of germinability was observed in seeds dried at 30 °C. Moreover, there was a notably higher solute leakage and a higher level of lipid hydroperoxides. Seeds dried at 30 °C contained less PC and PE and a lower level of unsaturated fatty acids (18:2 and 18:3), sterols and α-tocopherol. These results as well as changes in ascorbate and glutathione contents provide conclusive evidence for the presence of oxidative stress in beech seeds desiccated at 30 °C, which damaged membranes due to increased lipid peroxidation and changed membrane structure leading to their enhanced sensibility to free radical attack during storage.