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1.
以来自不同水分生境的金发藓和湿地匐灯藓为材料,对二者在脱水与复水胁迫条件下的活性氧代谢、脂质过氧化损伤程度及其抗氧化系统应答的差异进行比较研究。结果显示:在脱水与复水过程中,(1)硅胶快速脱水更接近阳光直射条件下藓类植物的水分丧失。(2)随着含水量的变化,湿地匐灯藓虽然能够在复水后迅速修复细胞的完整性,但变化剧烈;金发藓则能够始终维持较低的膜透性。(3)2种藓类植物的丙二醛(MDA)含量变化均呈先升后降趋势,但金发藓的MDA含量明显低于湿地匐灯藓。(4)2种藓类植物的超氧阴离子自由基(O2.-)产生速率和过氧化氢含量(H2O2)的变化均与MDA含量变化相似,且金发藓活性氧水平明显高于湿地匐灯藓。(5)2种藓类植物的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性受活性氧诱导亦呈先升后降的趋势,但金发藓抗氧化酶对活性氧迸发的应答更快,活性更强。(6)2种藓类植物的抗坏血酸(AsA)含量呈先降后升态势,但金发藓的含量低于湿地匐灯藓。研究表明,来自不同生境的2种藓类植物对脱水胁迫所致的氧化胁迫均具有很强的适应能力,尤其是复水过程中的修复能力,但不同藓类可能通过不同途径和机制来适应脱水所致的氧化胁迫;来自易发生水分亏缺生境的金发藓可能因具有更强抗氧化能力,从而获得比来自水分充沛生境的湿地匐灯藓更高的脱水耐性。  相似文献   

2.
铅胁迫对3种藓类植物细胞伤害及光合色素含量的影响   总被引:6,自引:1,他引:5  
采用水培实验研究了重金属Pb2+胁迫下3种藓类植物[尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)]的细胞伤害、光合色素含量和Pb2+累积量的变化,以探讨藓类植物对Pb2+胁迫的反应敏感性和耐性强弱.结果表明:(1)Pb2+胁迫导致尖叶拟船叶藓、湿地葡灯藓和匍枝青藓叶细胞显著损伤的最低浓度分别为100、1和10 mg·L-1,叶细胞伤害随Pb2+浓度的升高而显著增加,它们对高浓度Pb2+的耐受性顺序为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)低浓度Pb2+胁迫(小于100 mg·L-1)对3种藓类植物的总叶绿素含量均没有影响,高浓度Pb2+胁迫则导致总叶绿素含量显著下降,降幅依次为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;叶绿素a/b值显示,高浓度Pb2+胁迫对尖叶拟船叶藓叶绿素b的抑制远大于叶绿素a,而对匍枝青藓和湿地葡灯藓使叶绿素a的抑制大于叶绿素b;当Pb2+胁迫浓度达到200 mg·L-1时3种藓类植物的类胡萝卜素含量显著降低;(3)3种藓类植物均能显著地富集Pb2+,高浓度Pb2+胁迫下,其富集能力急剧增加,而且与其耐受性呈正相关.  相似文献   

3.
镉胁迫下3种藓类植物抗氧化酶活性变化的比较研究   总被引:13,自引:2,他引:11  
采用水培实验研究了重金属Cd对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶系统(SOD、POD和CAT)的影响.结果表明,在1-100 mg·L-1的镉胁迫浓度范围内,Cd对3种藓类植物的SOD活性都具有显著的促进作用,SOD对Cd胁迫的种间敏感性顺序为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;3种藓类植物的POD和CAT活性对Cd胁迫均表现为先升后降,POD对Cd胁迫的种间敏感性顺序为匍枝青藓>湿地匍灯藓>尖叶拟船叶藓;高浓度Cd对CAT具有明显的抑制效应,CAT对Cd胁迫的种间敏感性顺序为湿地匍灯藓>尖叶拟船叶藓>匍枝青藓.在Cd长期胁迫下,SOD对3种藓类植物体内活性氧的清除起到关键作用,可作为藓类植物抗镉能力强弱的敏感生理指标;3种鲜类植物中匍枝青藓的抗镉能力最强,湿地匍灯藓次之,尖叶拟船叶藓最弱,并且这种抗性与cd在植物体内的积累成反相关.  相似文献   

4.
镉胁迫下三种藓类植物的细胞伤害及光合色素含量的变化   总被引:2,自引:0,他引:2  
采用水培试验研究了不同浓度Cd胁迫下3种藓类植物的细胞伤害、光合色素含量和Cd含量的变化,以探讨其对Cd胁迫的反应敏感性和耐性.结果表明:低浓度Cd(1 mg.L-1)胁迫显著损伤尖叶拟船叶藓和匍枝青藓叶细胞,3种藓的叶细胞伤害率随Cd浓度的升高而显著增加,高浓度Cd(100 mg.L-1)胁迫下的细胞伤害率大小为匍枝青藓湿地匍灯藓尖叶拟船叶藓.低浓度Cd胁迫(1 mg.L-1)对3种藓类植物的总叶绿素含量无显著影响,随着Cd胁迫浓度的增加(≥10 mg.L-1),3种藓类植物总叶绿素含量显著下降,降幅顺序为匍枝青藓湿地匍灯藓尖叶拟船叶藓;1和10 mg.L-1 Cd胁迫对3种藓类植物叶绿素a/b值无显著影响,100 mg.L-1 Cd胁迫下湿地匍灯藓和匍枝青藓叶绿素a/b值显著下降;Cd胁迫对匍枝青藓类胡萝卜素含量的影响最大,1 mg.L-1 Cd下其类胡萝卜素含量显著降低.3种藓类植物均能显著地富集Cd,其体内Cd累积量以尖叶拟船叶藓最高,湿地匍灯藓次之,匍枝青藓最少.细胞伤害率、叶绿素和类胡萝卜素含量的变化可用来指示3种藓类植物对Cd胁迫的敏感性差异.尖叶拟船叶藓对Cd胁迫的耐受性最强,湿地葡灯藓和匍枝青藓相对较弱.3种藓类植物对Cd胁迫的耐受性与其体内Cd累积量呈明显的正相关关系.  相似文献   

5.
以来自不同水分生境的金发藓(Polytrichum commune)和湿地匐灯藓(Plagiomnium acutum)为材料,利用叶绿素荧光成像技术比较了脱水和复水过程中两种藓类的荧光光响应曲线、光系统Ⅱ光能转化效率(ratio ofchlorophyll variation fluorescence,Fv/Fm)、光系统Ⅱ光量子产量(quantum yielding of PSⅡ,Y(Ⅱ))、光化学猝灭(photochemical quenching,qP)和非光化学猝灭(none-photochemical quenching,NPQ)的变化.结果显示,在脱水过程中,金发藓的抑制光强可维持在800μmol/(m2.s)以上,而湿地匐灯藓可低至400μmol/(m2.s)左右;金发藓ETR(electron transportation rate)值始终可维持在20附近,而湿地匐灯藓可降至0;两种藓类的Fv/Fm、Y(Ⅱ)、qP均下降,但金发藓较湿地匐灯藓高;NPQ先升后降,金发藓的峰值早于湿地匐灯藓,而幅度低于湿地匐灯藓.在复水过程中,两种藓类抑制光强和ETR均迅速恢复后略有下降,金发藓的恢复较湿地匐灯藓慢但波动小;两种藓类Fv/Fm和Y(Ⅱ)均能恢复到正常水平,金发藓均高于湿地匐灯藓;两种藓类qP略有上升,NPQ则略有下降.说明藓类植物对脱水伤害的耐受能力主要体现在复水的修复能力上,而脱水持续和程度会对不同生境的藓类产生不同的胁迫效应.从光保护能力的角度来看,生活于易产生水分亏缺条件下的金发藓比生活在水分充沛条件下的湿地匐灯藓具有更强的脱水耐受能力.  相似文献   

6.
铅胁迫对3种藓类植物抗氧化酶活性的影响   总被引:6,自引:0,他引:6  
采用水培实验研究了重金属Pb对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶(SOD、POD和CAT)活性的影响.结果表明,(1)在1~200 mg·L-1的铅胁迫浓度范围内,Pb对3种藓类植物的SOD活性均具有显著的促进作用,对Pb胁迫的种间敏感性差异为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)POD活性对Pb胁迫的反应趋势有一定差别,尖叶拟船叶藓和匍枝青藓的POD活性随Pb浓度的增加先升后降,湿地匍灯藓的POD活性变化较为平缓,种间敏感性差异为匍枝青藓>尖叶拟船叶藓>湿地匍灯藓;(3)在100 mg·L-1时Pb对湿地匍灯藓CAT活性表现为显著促进作用外,其余在低浓度下显示无显著影响,在高浓度下表现为抑制效应,种间敏感性差异为尖叶拟船叶藓>匍枝青藓>湿地匍灯藓.3种藓类植物的抗氧化酶体系中对Pb胁迫的抵抗起关键作用的是SOD,可作为藓类植物受Pb胁迫的敏感生理指标.3种植物中对Pb胁迫的反应较为敏感的是尖叶拟船叶藓.  相似文献   

7.
李永刚  张元明 《生态学报》2018,38(23):8408-8416
苔藓结皮作为生物土壤结皮演替的最高阶段和生物量的最主要贡献者,具有很强的环境适应性,对维持荒漠地表稳定和改善微环境具有重要作用。非结构性碳水化合物是植物重要的组成部分,能够抵御环境胁迫对植物造成的损伤。目前,荒漠藓类植物非结构碳水化合物对干旱的响应机制尚不清楚。选取古尔班通古特沙漠南缘和腹地苔藓结皮中优势藓类植物齿肋赤藓(Syntrichia caninervis)为研究对象,对其在复水后脱水过程中非结构性碳水化合物含量变化特征进行了分析。结果表明:植株含水量在脱水24 h内下降趋势显著,此后趋于稳定。可溶性总糖、蔗糖、果糖、淀粉含量在脱水1h内显著下降。可溶性总糖、蔗糖、果糖、淀粉含量在脱水2—16 h没有显著的变化。但16—24 h可溶性总糖、蔗糖、果糖、淀粉含量出现显著增加,脱水24—48 h,腹地齿肋赤藓可溶性总糖、蔗糖、果糖、淀粉含量缓慢下降到复水前水平,而南缘可溶性总糖、蔗糖、果糖含量低于复水前水平。复水前不同地区齿肋赤藓非结构性碳水化合物含量存在显著性差异,脱水结束后两个地区齿肋赤藓非结构碳水化合物含量无显著差异。结果说明齿肋赤藓在不同地区其非结构性碳水化合物含量不同,在同一脱复水过程中不同地区齿肋赤藓非结构性碳水化合物含量表现出不同的变化趋势,主要原因是可溶性糖含量对脱水过程中水分胁迫的响应不同。齿肋赤藓脱水过程中非结构性碳水化合物的研究,有助于抗旱非维管植物在干旱环境中从降雨湿润进入干旱过程的适应策略研究。  相似文献   

8.
高温胁迫下两种藓类植物过氧化物酶活性的变化   总被引:18,自引:1,他引:17       下载免费PDF全文
刘应迪  曹同  向芬  彭春晖 《广西植物》2001,21(3):255-258
在不同的高温胁迫条件下 ,对湿地匍灯藓 (Plagiomnium acutum)和大羽藓 (Thuidium cymbifolium)过氧化物酶 (POD)活性及其与处理时间和处理温度的关系进行了初步研究。结果表明 ,在一定的温度范围内 ,随着温度的升高 ,POD活性增加 ,二者成线形关系。在一定温度条件下 ,一般随着处理时间的延长 ,POD活性增加。但是当超过一定的温度 (4 5~ 5 0°C)以及一定的处理时间 (4~ 6h) ,POD活性有所下降。结果还表明 ,湿地匍灯藓的POD活性显著高于大羽藓。而且在高温胁迫下 ,湿地匍灯藓 POD活性变化比大羽藓活跃 ,其变化幅度也比大羽藓大。  相似文献   

9.
杜晓濛  李菁  田向荣  李朝阳  李鹄鸣 《生态学报》2014,34(23):6807-6816
以广布湿生藓类——湿地匐灯藓(Plagiomnium acutum)为比较材料,研究东亚特有濒危植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)在不同快速脱水和复水胁迫下PSⅡ的叶绿素光合荧光变化和活性氧代谢及抗氧化系统变化,探讨两种藓类生理生态适应性差异的成因,以初步确定尖叶拟船叶藓受水分条件限制分布狭窄趋于濒危的原因。结果显示:(1)尖叶拟船叶藓的光合电子传递在脱水后可被极微弱光完全抑制,其抑制光强的恢复明显慢于湿地匐灯藓;其PSⅡ最大光化学效率(Fv/Fm)和实际光化学量子效率(YⅡ)先降而后升,恢复较慢;光化学淬灭(q P)复水后恢复较快,非光化学淬灭(NPQ)的绝对值和变化速率则始终低于湿地匐灯藓。(2)尖叶拟船叶藓活性氧水平明显高于湿地匐灯藓;其SOD、CAT、APX等抗氧化系统酶活性整体变化幅度较大,抗氧化保护物质(As A)含量则明显低于湿地匐灯藓。以上结果表明尖叶拟船叶藓受到环境水分因子限制的原因主要有:(1)PSⅡ的反应中心色素(P680)对脱水伤害较为敏感;(2)复水修复过程中抗氧化保护系统的保护能力偏低。  相似文献   

10.
以细叶小羽藓为试材,分别设置全光照、遮光30%、遮光50%和遮光70%条件,采用人工控水方法研究了干旱胁迫与复水过程中细叶小羽藓的质膜透性、渗透调节能力及抗氧化酶系统的变化.结果表明:于旱胁迫过程中,细叶小羽藓的相对含水量呈下降趋势,而相对电导率在干旱21 d时达到最大值,且全光照下的相对电导率最高(58.0%);可溶性糖和游离脯氨酸含量均先上升后下降;超氧化物歧化酶(SOD)和过氧化物酶(POD)活性先持续上升而后下降.在复水过程中,细叶小羽藓的相对含水量与干旱胁迫时相反;相对电导率、可溶性糖含量、游离脯氨酸含量、SOD和POD活性先小幅回升后逐渐下降,但SOD和POD活性仍较高;复水后大部分指标都恢复到干旱胁迫前水平.细叶小羽藓具备复苏植物的典型特征,在变水过程中有较强的抗旱能力.  相似文献   

11.
《Journal of bryology》2013,35(4):281-286
Abstract

The effects of treatments that increase desiccation tolerance were tested on the activity of the enzymes superoxide dismutase (SOD) and catalase (CAT) in the moss Atrichum androgynum subjected to a drying/wetting cycle. Hardening by both abscisic acid (ABA) pretreatment and partial dehydration significantly increased the rate of recovery of photosynthesis during rehydration following desiccation. Hardening treatments had little effect on SOD activity. In non-hardened plants, SOD activity increased three-fold during desiccation for 32 h at 52% rh, but hardened material tended to display smaller increases in activity. During rehydration, SOD activities rapidly declined to their initial values in all treatments. Hardening by partial dehydration, but not ABA, reduced CAT activity. After desiccation for 32 h, material from all treatments displayed about half the initial CAT activity, and activity did not change during subsequent rehydration. Results show that, while the induction of SOD appears to play a role in desiccation tolerance, a similar induction occurred in both hardened and non-hardened mosses. Induction of greater activities of enzymes that scavenge reactive oxygen species is not responsible for the added tolerance induced by hardening treatments.  相似文献   

12.
Recovery from desiccation by Tortula ruralis (Hedw.) Gaertn., Meyer and Scherb was accompanied by an immediate, rapid increase in respiration (measured as oxygen uptake) at 25.5°C or 3.5°C. The respiratory burst was greater on rehydration of moss which had been rapidly desiccated over silica gel than that which had been more slowly desiccated in atmospheres of high relative humidity. No respiration was observed in dry moss. Dried moss which had been placed in liquid nitrogen resumed respiration on rewarming and rehydration but moss which had been frozen in the hydrated state respired to a lesser extent and showed signs of freeze damage. In the initial stages of slow drying a slight increase in respiration was noted, followed by a gradual decrease as drought became more severe. In contrast to observations made on many higher plants under drought stress, this moss did not exhibit any changes in its starch and sugar content during or following desiccation, nor were there any changes in free proline levels. Using (1-14C)-glucose and (6-14C)-glucose, the relative activities of the Embden–Meyerhof–Parnas and pentose phosphate pathways in hydrated and rehydrated moss were determined, as were the activities of specific enzymes involved in these pathways. An increased activity of the Embden–Meyerhof–Parnas pathway of glucose oxidation on rehydration of Tortula was observed. The possible significance of this latter observation is outlined.  相似文献   

13.
Burritt DJ  Larkindale J  Hurd CL 《Planta》2002,215(5):829-838
Seaweeds grow in distinct vertical bands on the seashore and it is well known that their ability to recover physiological processes following desiccation is correlated to their shore position. Despite this, little is known of the cellular mechanisms by which intertidal seaweeds limit membrane damage during desiccation and subsequent rehydration. In this study, specimens of the intertidal red seaweed Stictosiphonia arbuscula were placed in sealed tanks and maintained at different relative humidities (control, RH 90-100%; moderate desiccation, RH 70-80% and severe desiccation, RH 40-50%) for 12, 24 or 48 h. Membrane damage and antioxidant metabolism was examined immediately following specimen rehydration. Amino acid leakage, through the plasmalemma, was greater for desiccated low-band specimens than high-band specimens, indicating greater membrane damage. In addition, low-band specimens produced more hydrogen peroxide and lipid hydroperoxides than high-band specimens. This indicates that, upon rehydration, high-band populations have a greater ability to reduce the build-up of hydrogen peroxide, limit lipid peroxidation and hence membrane and protein damage, than low-band populations. The greater ability to prevent or reduce the production of reactive oxygen species was not due to a larger antioxidant pool, but rather increased activity of the enzymes required to regenerate ascorbate and glutathione. These findings suggest that antioxidant metabolism is one of the defence mechanisms that protect S. arbuscula from cellular damage due to desiccation.  相似文献   

14.
顽拗性黄皮种子脱水过程中活性氧清除酶活性的变化   总被引:1,自引:0,他引:1  
以正常性种子花生为对照,研究了顽拗性黄皮种子脱水过程中活性氧清除酶、膜脂过氧化作用以及电解质渗漏率的变化。随着含水量的下降,黄皮胚的电解质渗漏率和膜脂过氧化产物丙二醛(MDA)含量均显著增加;当黄皮胚含水量下降至40%后,SOD活性开始急剧下降,而POD和CAT活性在胚含水量下降过程中呈现出缓慢下降的趋势。花生胚在含水量从45%降至14%的过程中,电解质渗漏率没有明显增加,MDA含量只有少量增加;当含水量降至14%后,电解质渗漏率出现少量增加。花生胚脱水初期,活性氧清除酶活性明显增加,并在整个脱水过程中维持较高的水平。以上结果表明顽拗性种子黄皮的脱水敏感性与活性氧清除酶相对活性变化有关。脱水引起黄皮胚活性氧清除酶活性降低,活性氧清除能力下降,膜脂过氧化作用加强,膜透性增大。黄皮胚的膜系统可能是脱水伤害的靶位之一。  相似文献   

15.
In order to investigate changes of oxidative status in relation to the activity of the various protective mechanisms in resurrection plant Ramonda nathaliae, we have analysed time and relative water content (RWC) related changes in lipid peroxidation and ion leakage, hydrogen peroxide accumulation, changes of pigment content and antioxidative enzyme activity, together with expression of dehydrins. The results indicate that enhanced oxidative status during dehydration, not previously reported for resurrection plants, could play an active role in inducing the desiccation adaptive response in R. nathaliae. A critical phase is shown to exist during dehydration (in the range of RWC between 50 and 70%) during which a significant increase in hydrogen peroxide accumulation, lipid peroxidation and ion leakage, accompanied by a general decline in antioxidative enzyme activity, takes place. This phase is designated as a transition characterized by change in the type of stress response. The initial response, relying mainly on the enzymatic antioxidative system, is suspended but more effective, desiccation specific protective mechanisms, such as expression of dehydrins, are then switched on. The expression of dehydrins in R. nathaliae could be inducible as well as constitutive. In order to cope with the oxidative stress associated with rapid rewatering, R. nathaliae reactivated antioxidative enzymes. We propose that controlled elevation of reactive oxygen species, such as hydrogen peroxide, could be an important mechanism enabling resurrection plants to sense dehydration and to trigger an adaptive programme at an appropriate stage during the dehydration/rehydration cycle.  相似文献   

16.
Haberlea rhodopensis belongs to the small group of resurrection plants having the unique ability to survive desiccation to air dry state retaining most of its chlorophyll content and then resume normal function upon rehydration. It prefers the shady valleys and northward facing slopes of limestone ridges in mountain zones with high average humidity. Nevertheless, it can be found rarely on rocks directly exposed to the sunlight, without the coverage of the canopy. In the present study, we follow the alterations in the subcellular organization of mesophyll cells and sugar metabolism upon desiccation of shade and sun H. rhodopensis plants. Composition and content of soluble carbohydrates during desiccation and rehydration were different in plants grown below the trees or on the sunny rocks. Sucrose, however, was dominating in both ecotypes. The amount of starch grains in chloroplasts was inversely related to that of sugars. Concomitantly with these changes, the number of vacuoles was multiplied in the cells. This can be explained by the development of small (secondary) vacuoles peripherally in the cytoplasm, rather than by the fragmentation of the single vacuole, proposed earlier in the literature. Accordingly, the centripetal movement of chloroplasts and other organelles may be a result of the dynamic changes in the vacuolar system. Upon rehydration, the inner vacuoles enlarged and the organelles returned to their normal position.  相似文献   

17.
18.
以典型荒漠丝状蓝藻爪哇伪枝藻为材料,在温室中设置水合(对照)、轻微干燥、中度干燥和极度干燥4种处理,研究干燥胁迫对藻体光合活性、膜脂过氧化、细胞可溶性物质含量、抗氧化酶活性以及细胞超微结构的影响,并采用不同促进剂和抑制剂对干燥藻体进行再吸水处理,测定藻体光合活性的恢复情况。结果显示:(1)爪哇伪枝藻在干燥胁迫下PSⅡ最大光化学效率(Fv/Fm)显著降低,并与其藻体水分含量之间呈极显著性相关(r=0.97、P<0.000 1);(2)随着干燥胁迫程度增加,藻体MDA含量、SOD和CAT活性随之升高,细胞可溶性蛋白和可溶性糖含量增加;(3)在藻体再吸水条件下,培养液(BG-110)、胞外多糖和蔗糖对藻体Fv/Fm的恢复具有重要作用,N-乙酰半胱氨酸和脯氨酸对Fv/Fm有一定的恢复效果,氯霉素和敌草隆则抑制Fv/Fm;(4)与水合状态下的细胞结构相比,干燥藻体细胞结构发生明显的变化,如细胞壁增厚,原生质粘稠浓缩、呈紧密分层排列,细胞内出现大量细小黑色颗粒物等。(5)采用不同外源物质对干燥藻体进行再吸水时,藻体的光合活性呈现不同的恢复效果。研究表明,干燥胁迫下爪哇伪枝藻的光合活性受到明显抑制,细胞质膜过氧化程度加剧,细胞出现可溶性小分子物质积累,抗氧化酶活性增强,并造成细胞结构出现适应性变化。  相似文献   

19.
Seeds of yellow lupine (Lupinus luteus L. cv. Juno) were collected throughout their development on the mother plant to determine whether the ability to germinate and to tolerate desiccation is related to the level of free radicals and the changes in the redox state of ascorbate and glutathione as well as the activities of antioxidative enzymes. Electron paramagnetic resonance (EPR)-based analyses showed that development of lupine seed was accompanied by generation of free radicals with g1 and g2 values of 2.0049 ± 0.0004 and 2.0029 ± 0.0003, respectively. Free radical level increased significantly 25 DAF and decreased thereafter. The amount of hydrogen peroxide was high in fresh immature seeds and decreased during maturation drying. Ascorbate accumulated in lupine embryos during early seed filling stage whereas glutathione content increased during late seed filling phase. During maturation drying the redox state of both ascorbate and glutathione pools shifted towards the oxidized forms. While superoxide dismutase (SOD, EC 1.15.1.1), and ascorbate peroxidase (APX, EC 1.11.1.11) activities remained high at the early seed filling stage the activities of both dehydroascorbate reductase (DHAR, EC 1.8.5.1) and glutathione reductase (GR, EC 1.6.4.2) and that of catalase (CAT, EC 1.11.1.6) increased before seeds reached physiological maturity and decreased thereafter. The changes of isoform patterns of antioxidative enzymes were observed during seed maturation. Immature lupine seeds tested immediately after harvest acquired the ability to germinate when less than half-filled and reached high tolerance to desiccation just after physiological maturity. The physiological implications of the changes in antioxidative machinery for the acquisition of desiccation tolerance and seeds germinability are discussed.  相似文献   

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