苦豆子和披针叶黄华种子硬实特性与活力关系研究

以苦豆子和披针叶黄华种子为实验材料,在恒温25℃下吸胀,每24h取出吸胀种子,10d后未吸胀的种子为硬实种子(H),硬实种子用硫酸处理后恒温吸胀24h,与非硬实种子进行发芽试验和各项活力指标测定。结果显示:(1)每日内吸胀的种子数量随时间推移以一定比列下降,苦豆子非硬实种子吸胀速率较缓慢,第10天后吸胀率降到1%,披针叶黄华非硬实种子第3天后下降到1%,第9、10天突然上升后又下降到1%。(2)两种豆类种子都显示出硬实种子发芽率、发芽指数、活力指数、脱氢酶、呼吸速率、超氧化物歧化酶(SOD)均高于非硬实种子,而电导率、浸出液可溶性糖和丙二醛(MDA)均低于非硬实种子,缓慢吸胀的硬实种子活力指标高于快速吸胀的硬实种子。研究表明,硬实种子活力高于非硬实种子,硬实种子吸胀过程中存在吸胀损伤。而在非硬实种子中,根据以上活力指标判断,晚吸胀的种子比早吸胀的种子活力高。     

苦马豆和披针叶黄华种子硬实特性与活力关系

将苦马豆和披针叶黄华种子在恒温25℃下吸胀,每24 h取出吸胀种子,16 d后未吸胀的种子为硬实种子（H）,硬实种子用硫酸处理后恒温吸胀24 h,与非硬实种子进行发芽试验和各项活力指标测定。结果显示每日内吸胀的种子数量随时间推移以一定比列下降,苦马豆非硬实种子第3天后吸胀率下降到1%,第13～16天突然上升后又下降到1%,披针叶黄华非硬实种子第3天后下降到1%,第9、10天突然上升后又下降到1%。两种豆类都显示出硬实种子发芽率、发芽指数、活力指数、脱氢酶活性、呼吸速率和超氧化物歧化酶（SOD）活性均高于非硬实种子,而电导率、浸出液可溶性糖和丙二醛（MDA）含量低于非硬实种子,缓慢吸胀的硬实种子活力指标高于快速吸胀的硬实种子,这表明硬实种子活力高于非硬实种子,硬实种子吸胀过程中存在吸胀损伤。而在非硬实种子中,根据以上活力指标判断,晚吸胀的种子比早吸胀的种子活力高。     

预吸胀对绿豆种子脱水耐性的影响

绿豆 (Vignaradiata)种子的吸水曲线未出现明显的“平稳期”。种子萌发 5 0 %的时间和热时间分别为 11h和 11 5度天。在吸胀初期 ,种子的相对电导率迅速增加 ,然后下降。随着脱水时间的延长 ,预吸胀不同时间的绿豆种子的含水量和存活率、由存活种子产生的幼苗鲜重、胚根和下胚轴长度明显下降 ;而且随着预吸胀时间的增加 ,种子对脱水的敏感性显著加强 ;预吸胀种子的相对渗漏率在脱水初期缓慢增加 ,然后迅速增加 ,且预吸胀时间愈长 ,相对渗漏率增加的幅度愈大。结果表明预吸胀的绿豆种子的脱水耐性是逐渐丧失的 ;吸胀的能萌发的正常性种子的脱水敏感性可以作为研究种子顽拗性的一种模式系统     

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。     

钙对吸胀的绿豆种子脱水耐性的影响

以绿豆种子为材料,研究了预吸胀种子脱水耐性的变化,以及Ca^2 处理对种子脱水耐性的影响。结果表明：绿豆种子的脱水耐性随预吸胀时间的延长而下降;Ca^2 预吸胀处理能提高种子的脱水耐性,适宜的Ca^2 浓度为20mmol／L;Ca^2 能修复预吸胀种子的脱水伤害,适宜的Ca^2 浓度为2．5～5mmol／L。     

花生种子活力与贮藏蛋白质降解的关系

花生种子吸胀2d后,子叶中肽链内切酶活性上升,贮藏蛋白质开始降解。高活力种子肽链内切酶活性在吸胀2d后迅速上升,至4d时达到高峰,而中等活力种子的肽链内切酶活性上升速度绶慢。高活力种子萌发时贮藏蛋白质降解速度高于中等活力种子。中等活力种子经PEG和PUT处理可提高种子活力,也促进了种子贮藏蛋白质降解能力的提高。     

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.     

花生种子活力与贮藏蛋白质降解的关系

花生种子吸胀2d后,子叶中肽链内切酶活性上升,贮藏蛋白质开始降解。高活力种子肽链内切酶活性在吸胀2d后迅速上升,至4d时达到高峰,而中等活力种子的肽链内切酶活性上升速度缓慢。高活力种子萌发时贮藏蛋白质降解速度高于中等活力种子。中等活力种子经PEG和PUT处理可提高种子活力,也促进了种子贮藏蛋白质降解能力的提高。     

西瓜种子内源β-半乳甘露聚糖酶活性与分布以及与萌发速度的关系

利用单粒种子凝胶扩散法研究了β-半乳甘露聚糖酶在西瓜种子萌发过程中的分布以及与西瓜种子萌发速率的关系。结果发现,在胚根尖突破种皮前吸胀的西瓜种子中,内源β-半乳甘露聚糖酶主要分布于种子的胚膜套中,并起到减弱外种皮和胚膜套细胞壁对胚根伸出的机械阻力的作用。对具有不同萌发速率的品种以及引发处理和未处理的西瓜种子中酶活性的检测证明,β-半乳甘露聚糖酶活性与西瓜种子萌发速度相关。固体基质引发三倍体西瓜种子过程中β-半乳甘露聚糖酶的活化和种皮阻力的减弱,是引发种子提高了萌发速度和萌发能力的原因之一。     

豌豆种子吸胀过程中脱水耐性变化的时间模式

研究了豌豆种子吸胀过程中脱水耐性的变化模式。种子在吸胀初期迅速吸收水分,然后缓慢吸收直到平台期。电解质渗漏速率在吸胀初期增加直到11h,然后随着吸胀下降。在吸胀过程中,种子的萌发率逐渐增加,种子和胚轴的脱水耐性逐渐丧失,10％和50％的种子和胚轴被脱水致死的含水量明显增加。赤霉素和脱落酸处理改变豌豆种子的萌发特性,提高胚轴的脱水耐性。研究结果表明,吸胀的豌豆种子脱水耐性的丧失是一种数量性状,正常性种子吸胀后脱水耐性的变化能够作为种子顽拗性研究的模式系统。     

Effect of Low Temperature lmbibition on Mito chondrium Respiration and Phosphorylation of PEG Primed Soybean Seed

Cotyledon mitochondrium respiration and oxidative phosphorylation activity of PEG primed and unprimed (control) soybean seeds which have been exposed to low temperature imbibition before germination are studied. The ADP stimulated respiration rates of control mitochondria are evidently higher than state Ⅲ respiration rates of mitochondria from primed seed when L-Mal, α-Kg and Succ are used as substrates respectively. The mitochondria from the unprimed do not possess respiratory control (RC.) On the contrary, mitochondria from the primed, even after seeds being exposed to 2–3 ℃ imbibition for 24 h, phosphorylate normally. The ADP/O and RC values are consistent with those of theoretical expectation. When NADH is used as substrate, unprimed seed mitochondria still possess oxidative phosphorylation activity, while ADP/O and RC values are obviously lower than those of mitochondria from the primed. The emerging sequence of the activity of the diverse phosphorylation sites during germination is also studied. When a different substrate is used, the emerging sequence of the primed is as follows: 1. NADH (12 h), 2.α-Kg (24 h), 3. L-Mal and Succ (48 h). This corresponds to occurrence sequence of ADP stimulated respiration in control mitochondria. The above results show that low temperature imbibition has an irreversible destructive effect on oxidative phosphorylation activity of control mitochondria, and PEG priming has a protective effect on structure and function of the mitochondria under low temperature imbibition stress. The mechanism of soybean imbibitional chilling injury and protective effect of PEG priming are discussed.     

PVA和PEG(6000)预处理对大豆胚轴生长、蛋白质合成和ATP含量的影响

在低温吸胀阶段,经PVA(聚乙烯醇)和PEG(聚乙二醇6000)预处理的大豆胚轴蛋白质合成和ATP含量均比对照高。在萌发阶段,胚轴生长增快,蛋白质合成明显加快,ATP迅速被消耗,而对照胚轴则相反。试验结果表明,预处理大豆种子萌发和生长与其蛋白质合成、ATP水平和消耗能力有密切关系。     

Chemiluminescence during rice seed imbibition at different temperatures.

The chemiluminescence (CL) of rice (Oryza sativa L.) seeds at different temperatures and the CL spectra of rice seed, caryopses and seed coat were studied during early imbibition. Compared with the CL of barley (Hordeum vulgare L.) and soybean (Glycine max L. Merr.) seeds, the CL of rice seeds had a non-linear, logarithmic-like increase of intensity in the temperature range 30-50 degrees C. The Van't Hoff coefficient Q(10) = I(T+10)/I(T) was equal to 2. The emission spectrum of whole rice seed, rice and coat had a greater proportion of red light during early imbibition, which led to the conclusion that the CL of rice seed during early imbibition arises partially from enzyme-catalysed reactions.     

The use of image analysis to monitor the germination of seeds of broccoli (Brassica oleracea) and radish (Raphanus sativus)

To study broccoli and radish seed germination under different temperature regimes the germination test has been used to assess final germination percentage, start and rate. This method has been integrated with a computer‐aided image analysis test which is more accurate in monitoring the extent of imbibition phases through the assessment of seed area increase and timing of radicle emergence detected on single seeds. In addition, seed area increase has been used also to establish a close relationship with radicle elongation rate in the time range when ‘visible germination’ is scored by a classical germination test. The results suggest that this image analysis parameter may be considered as a reliable seed imbibition marker to integrate the germination parameters obtained by a germination test.     

Physiological and enzymatic activity of pepper seeds (Capsicum annuum) during priming

Pepper ( Capsicum annuum L. cv. Keystone Resistance Giant 3) seeds were monitored during priming to determine if seed treatments which accelerate the rate of germination could be correlated with specific physiological changes within the seeds. Pepper seeds primed with −0.90 and −1.35 MPa NaCl solutions at 23°C for 18 days did not completely equilibrate with the osmotic potential of the priming solution. Seed respiratory rates indicated that priming extends the lag phase of germination following imbibition. Soluble protein levels increased 115% in primed seeds, and the uptake and incorporation of [¹⁴C(U)] labelled amino acids into the acid insoluble fraction increased throughout the priming treatments. Alcohol dehydrogenase (EC 1.1.1.1, anaerobic metabolism), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44, pentose phosphate pathway) activities remained stable throughout the priming treatment, but were higher after 6 days. than the water-imbibed controls. Aldolase (EC 4.2.1.1. glycolysis) and isocitrate lyase (EC 4.1.3.1, glyoxylate cycle) activities increased with imbibition and were 61 and 56% (respectively) higher in primed seeds as compared to the water-imbibed controls after 12 days. Treatment with the −0.90 MPa NaCl solution was more effective than the −1.35 MPa solution in improving the rate of germination, yet there were no significant differences between the protein concentrations or enzyme activities of the two priming treatments. However, the incorporation of labelled amino acids into pepper seeds was significantly higher in the −0.90 MPa priming treatment.     

Improved germination in seeds of guayule (Parthenium argentatum Gray) following polyethylene glycol and gibberellic acid pretreatments

Suitable conditions for the pretreatment of seeds of guayule were determined with a view to improving germination. These included the addition of thiram (500 mg litre^-1), and applications of GA₄₊₇ alone, or in combination with polyethylene glycol. Significant improvements in the seed germination were seen following applications of PEG at -0.10 MPa. Simultaneous application of GA₄₊₇ with priming improved soil emergence and germination over a wide range of temperatures. No beneficial effects of PEG priming were evident on seed storage.     

Stimulation of celery seed germination and seedling growth with combined ethephon,gibberellin and polyethylene glycol seed treatments

The upper-temperature limit for germination of cv. Celebrity celery seeds incubated in darkness in laboratory tests was slightly raised following a seed soak with a mixture of the gibberellins A₄ and A₇ + ethephon (G + E) but more so by osmotic priming with polyethylene glycol (PEG). However, the best effects were obtained with a combination of growth regulator and priming treatments. Incorporation of growth regulators into the PEG was more effective than soaking seeds in G + E solutions either before or after osmotic priming. In glasshouse tests, seedling emergence was more rapid, percentage emergence was higher and seedling weight was greater from seeds treated with PEG either alone or in combination with G + E than from untreated seeds, water-soaked seeds or seeds given G + E soaks before or after PEG treatment.     

大豆种子萌发过程中的差异蛋白质组研究

运用蛋白质组学技术对大豆(Glycinemax)N2899种子萌发0h、8h、36h、60h4个时期蛋白质的差异表达情况进行了研究.结果发现,在考马斯亮蓝染色的双向电泳pH3～10胶上,PDQuest图像分析软件可识别的点约350个,其中表达量变化2.5倍以上的蛋白质点有24个,而绝大部分大豆种子贮藏蛋白在萌发期尚未降解.在萌发的第一阶段,24个差异表达蛋白中有10个蛋白质的丰度发生变化.第二阶段,差异表达蛋白的种类和量增加,其中15个蛋白质是动态变化的,14个蛋白质在胚根突破种皮时表达量达到峰值,表明吸胀后种子内的生命活动越来越强.对这24个蛋白质点进行胶内酶解,用基质辅助激光解析电离飞行时间质谱测定均获得肽质量指纹图谱.搜索大豆的UniGene库初步鉴定出6个蛋白质,分别是核苷二磷酸激酶、热激蛋白、硫氧还蛋白、35ku种子成熟蛋白及种子成熟蛋白PM36.对这些蛋白质在种子萌发过程中可能的作用进行了讨论.     

菜用大豆种子活力与DNA,RNA及蛋白质合成的关系

菜用大豆种子随着其活力的下降,对DNA,RNA和蛋白质前体的吸收,以及合成这些大分子的能力都明显下降,已丧失合成DNA和蛋白质能力的失活种子,仍能进行微弱的RNA合成。高活力种子在吸胀初期DNA合成速率较低,然后增加,至16h达高峰;RNA的合成速率在吸胀一开始就很高,在整个吸胀过程中均保持较高水平;蛋白质的合成速率则在开始较高,并随着吸胀过程呈增强趋势。     

聚乙烯醇预处理提高大豆种子活力和抗冷能力的作用

聚乙烯醇预处理大豆种子和聚乙二醇一样,能明显地提高种子的活力、萌发率和抗冷能力。其主要作用可能是:在整个吸胀过程中减少了吸水速度,使膜的修复作用有足够的时间;启动和改善种子内部的生理代谢过程.保证了生长胚根有更多的物质供应。