枇杷种子的脱水敏感性与膜脂过氧化作用

枇杷种子不耐贮藏,属于脱水敏感的种子。在干燥脱水过程中,子叶和胚轴的超氧物歧化酶（ＳＯＤ）和过氧化物酶（ＰＯＤ）的活性不断下降,而丙二醛（ＭＤＡ）含量及种子浸泡液的电导率不断增加,种子活力逐渐降低。外源０．０５～０．２５ｍｍｏｌ／Ｌ的抗坏血酸（ＡＳＡ）,０．０５～０．２５ｍｍｏｌ／Ｌ的还原性谷胱甘肽（ＧＳＨ）和０．０５～０．５ｍｍｏｌ／Ｌ的Ｃａ＾２＋处理能有效地增强种胚防御过氧化的能力,缓解氧自由     

木波罗种子脱水敏感性与膜脂过氧化的研究

刚采收的木波罗种子含水量为５８．６％。随着含水量下降,种子的发芽率和发芽指数迅速下降,种子对脱水非常敏感,是典型的顽拗性种。自然脱水时,种子胚轴和子叶中超氧物歧化酶的活性先上升,然后下降,丙二醛和脂质氢过氧化物的含量显著增加。其脱水敏感性的原因可能是当种子脱水时,植物酶ＳＯＤ的活性下降,膜脂过氧化作用加强,从而使膜的结构和功能受到破坏,种子生活力丧失。     

黄皮种子脱水敏感性与脂质过氧化作用

黄皮种子自然脱水时,种子的发芽率和发芽指数迅速下降;种子浸泡液的电导率和可溶性物质的量大大增加;线粒体膜和质膜ＡＴＰａｓｅ的活性下降,种子中ＳＯＤ活性先上升,然后下降;脂质过氧化产物ＭＤＡ和脂质氢过氧化物的量大大增加。     

脱水方法对棕榈种子萌发及膜脂过氧化的影响

以棕榈种子为材料,比较了硅胶脱水和自然脱水方法下种子萌发特征和膜脂过氧化程度。结果表明:棕榈种子的初始含水量为33.1%,萌发率为83.3%;当硅胶脱水至含水量21.2%时萌发率为80.0%,而自然脱水至23.2%时萌发率仅为56.7%;当含水量降至10%左右时,硅胶脱水萌发率为27.7%,而自然脱水的萌发率为26.7%。在脱水过程中,2种脱水处理种子的浸出液电导率和丙二醛(MDA)含量都呈升高趋势,但自然脱水种子浸出液电导率升高的速率较硅胶脱水快,而MDA含量在硅胶脱水下增加较大。硅胶脱水处理种胚中脯氨酸含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性均较自然脱水高,但2种脱水处理种子整体均呈先增加再下降的趋势。研究发现,棕榈种子为中间型种子,其在脱水初期对自然脱水较敏感,而脱水后期脱水速率对其生活力影响较小;棕榈种子对硅胶脱水的脱水敏感较自然性脱水要低,硅胶脱水有利于改善棕榈种子的贮藏寿命。     

静电场处理种子对干旱下柠条幼苗膜脂过氧化作用的影响

基于静电场处理植物种子可以促进幼苗生长、提高产量和改变品质的认识，为探讨这项措施能否改善干旱条件下与植物抗干旱胁迫能力有关的生理特性问题，我们选择大小一致的柠条（Caraganacorshinskii）干种子，分别置于4．0kV／cm、4．5kV／cm和5.0kV／cm的静电场中处理10min，以不经静电场处理为对照。然后分别播种于放有细沙的花盆中，于室内（温度为20℃，自然漫射光）培养30d后停止浇水，此时苗高为6～8cm，土壤含水率为4．91％。待土壤自然回干第3d土壤含水率为2．54％，第5d为2．17％时，测定幼苗体内SOD活性（Giannopolitis，Ries…     

脱水速率对黄皮胚轴脱水敏感性及膜膜过氧化的影响

以黄皮种子离体胚轴为材料,研究了不同于燥速率对胚轴脱水反应和膜脂过氧化的影响。在脱水过程中,胚轴的萌发率,活力指数,电解质渗漏速率,超氧化物歧化酶（SOD）,过氧化物酶（POD）和过氧化氢酶（CAT）活性逐渐降低,膜脂过氧化产物MDA的含量不断增加,脱水速率愈快,胚轴的半致死含水量就愈低。快速干燥的胚轴能在较低的含水量存活是因为顾中间含量下发生的膜脂过氧化作用的时间,以及保持较高的SOD,POD和CAT活性,缓慢干燥的胚轴当与周围环境达到水分平衡后,生活力的丧失将与保持在水分平衡后的时间有关,。因此,脱水速率是一种影响顽拗性种子或者胚轴脱水敏感性的重要因子。     

黄皮种子脱水敏感性与脂质过氧化作用

黄皮种子自然脱水时,种子的发芽率和发芽指数迅速下降;种子浸泡液的电导率和可溶性物质的量大大增加;线粒体膜和质膜ATPase的活性下降;种子中SOD活性先上升,然后下降;脂质过氧化产物MDA和脂质氢过氧化物的量大大增加。DDC、MDA和Fe2 促进脂质过氧化作用,降低种子生活力;ASA和甘露醇对脂质过氧化有抑制作用,提高种子生活力。     

脱水速率对黄皮胚轴脱水敏感性及膜脂过氧化的影响

以黄皮种子离体胚轴为材料,研究了不同干燥速率对胚轴脱水反应和膜脂过氧化的影响.在脱水过程中,胚轴的萌发率、活力指数、电解质渗漏速率,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性逐渐降低,膜脂过氧化产物MDA的含量不断增加.脱水速率愈快,胚轴的半致死含水量就愈低.快速干燥的胚轴能在较低的含水量下存活是因为缩短了在中间含水量下发生的膜脂过氧化作用的时间,以及保持较高的SOD、POD和CAT活性;缓慢干燥的胚轴当与周围环境达到水分平衡后,生活力的丧失将与保持在水分平衡后的时间有关.因此,脱水速率是一种影响顽拗性种子或者胚轴脱水敏感性的重要因子.     

光对小麦幼叶脂氧合酶活性及膜脂过氧化作用的影响

选用抗旱型小麦品种陕合６号和水分敏感型小麦品种郑引１号的黄化幼苗为材料,研究了光处理对小麦幼叶脂氧合酶活性和膜脂氧化作用的影响。结果表明：光处理后黄叶变绿,叶片中的ＬＯＸ活性降低,丙二醛含量和叶绿素含量增加,膜透性升高,ＩＵＦＡ升高。ＬＯＸ活性与光抑制过程的恢复,光保护过程及膜脂过氧化作用有关。光诱导产生的膜脂过氧化作用是一种“准膜脂过氧化作用”。     

UVB对水稻幼苗膜脂过氧化作用的影响

ＵＶ－Ｂ处理的水稻幼苗,叶片的膜透性、Ｏ２－净产生速率及ＭＤＡ含量显著增加。在ＵＶ－Ｂ处理初期,活性氧防御系统中的ＳＯＤ和ＣＡＴ活性比对照增强,但随着处理时间的延长,ＳＯＤ和ＣＡＴ活性明显下降;ＰＯＤ活性受ＵＶ－Ｂ处理抑制。这一结果表明,ＵＶ－Ｂ降低了细胞内活性氧自由基的清除能力,膜脂过氧化作用加剧,最终导致伤害效应。     

枇杷茎尖二步玻璃化法超低温保存的研究

超低温保存是目前植物种质资源长期稳定保存最理想的方法,而近几年发展的玻璃化超低温保存法具有设备要求简单、材料处理步骤简便及效果和重演性好等特点,倍受人们的青睐。国内外用玻璃化法成功地保存许多果树的种质资源。在对枇杷（Eriobotrya japonica Lindl．）花粉超低温保存取得成功的基础上,作者进行了枇杷茎尖玻璃化超低温保存的研究,以期建立枇杷茎尖超低温保存体系,为长期稳定保存枇杷种质资源提供技术支持。     

枇杷4-香豆酸CoA连接酶的某些特性

以枇杷品种‘解放钟’果实为试材,用硫酸铵分级盐析方法提取4-香豆酸CoA连接酶,其最适温度为10和40℃,40和10℃下的热稳定性较好;最适pH为8．0且较稳定;最适底物为咖啡酸。     

Generation of (2-Nitroethyl)benzene and related benzenoids from L-Phenylalanine; flower scents of the Japanese Loquat Eriobotrya japonica [Rosales: Rosaceae]

ABSTRACT

(2-Nitroethyl)benzene, methyl 4-methoxybenzoate and 4-methoxybenzaldehyde have been known as major scent components in flowers of the Japanese loquat Eriobotrya japonica [Rosales: rosaceae], together with 13 related benzenoids, including Z- and E-2-phenylacetaldoxime and benzyl alcohol. The scents air-trapped from a flowering panicle during 24 h incubation with d₈-L-phenylalanine were composed of 15 deuterium labeled compounds {d₆-styrene, d₅-benzaldehyde, d₇-2-phenylacetaldehyde, methyl d₅-benzoate, d_{7 ?}2-phenylethanol, d₇-2-phenylacetonitrile, d₄-1,4-dimethoxybenzene, d₇-Z-2-phenylacetaldoxime, d₄-4-methoxybenzaldehyde, d₇-E-2-phenylacetaldoxime, d₄-4-methoxybenzyl alcohol, d₇-(2-nitroethyl)benzene, methyl d₄-4-methoxybenzoate, methyl d₆-cinnamate and ethyl d₄-4-methoxybenzoate}. On the other hand, hexane extracts of the flower petal incubate with a mixture of d₅-Z- and d₅-E-2-phenylacetaldoxime after 24 h indicated generation of six d₅-labeld components {d₅-benzaldehyde, d₅-benzyl alcohol, d₅-2-phenylacetaldehyde, methyl d₅-benzoate, d₅-2-phenylethanol, and d₅-(2-nitroethyl)benzene}. By comparing those results, (2-nitroethyl)benzene was concluded as a product directly generated from a mixture of Z- and E-2-phenylacetaldoxime together with six minor benzenoids, while two major compounds (4-methoxybenzaldehyde and methyl 4-methoxybenzoate) together with three minors from L-phenylalanine, presumably via L-tyrosine. The other two minor components were derived from L-phenylalanine.     

枇杷叶的化学成分

枇杷叶系蔷薇科（Rosaceae）枇杷属植物枇杷[Eriobotrya japonica（Thunb．）Lindl．]的干燥叶,为常用中药,收载于历版《中华人民共和国药典》中。枇杷叶归肺、胃经,具清肺止咳、降逆止呕的作用,用于治疗肺热咳嗽、气逆喘气、胃热呕逆及烦热口渴之症状。目前,已经从枇杷叶中分离出三萜酸、黄酮类、多酚、倍半萜及其苷类等成分,对其药效的研究主要集中在三萜酸的抗炎心、降血糖和抗病毒活性等方面。     

脱水导致种子和花粉细胞膜变化的生物热力学研究进展

膜系统是引起脱水敏感细胞的损伤和死亡的原初位点之一,该文综述了近年来对以下各问题以及它们之间的关系的研究进展:(1)膜相变;(2)膜系统和生物大分子受到的压力;(3)玻璃态的形成及其部位;(4)造成玻璃态形成的溶质分子的大小对膜相变的影响;(5)两性物质在细胞质水相和膜脂脂相间的再分配.旨在为如何有效地监控种子和花粉寿命和最大程度地减少种子和花粉细胞的衰老损伤,预测种质保存的最佳贮藏条件和种质寿命,以便及时更换保存样本等方面的研究提供新的思路.     

表油菜素内对月季切花中几种与膜脂过氧化相关生理指标的影响

2%蔗糖 200mg·L-1硼酸 0.5mg·L-1表油菜素内酯(epiBR)可减缓月季切花体内的超氧物歧化酶(SOD)活性和抗坏血酸含量的下降,削弱丙二醛(MDA)含量和细胞膜相对透性的上升幅度,从而延长切花的瓶插寿命。     

杂交水稻种子固有细菌群落多样性探究

采用传统的分离培养方法和分子生物学技术对我国高产杂交水稻(OryzasativaL.)金优611种子固有细菌进行研究,从而了解其中可培养细菌群落的多样性。对分离得到的91株细菌进行16SrDNA扩增、ARDRA分型和16SrDNA系统发育分析,结果表明,分离得到的91株细菌分属于10个属16个种。其中γ-变形杆菌(Gammaproteobacteria)(53.85%)占据优势地位,其次为α-变形杆菌(Alphaproteobacteria)(20.88%),其它分属放线菌门Actinobacteria(15.39%)及厚壁菌门Firmicutes(9.88%)。其中的泛菌属(Pantoea sp.)和鞘氨醇单胞菌属(Sphingomonas sp.)、假单胞菌属(Pseudomonas sp.)、微杆菌属(Microbacterium sp.)为分离到的优势种群,且在种子这一特殊的生存空间中有4株潜在的新种存在。首次报道了杂交水稻金优611种子具有丰富的微生物群落多样性,为进一步探索植物种子际微生态环境中微生物群落的形成和生态功能提供了基础信息。     

Accumulation of Storage Materials,Precocious Germination and Development of Desiccation Tolerance During Seed Maturation in Mustard (Sinapis alba L.)

Under defined environmental conditions (20°C, continuous light of 15 klx) development of mustard seeds from artificial pollination to maturity takes about 60 d. After surpassing the period of embryo cell division and histodifferentiation (12–14d after pollination = dap), the seed enters into a maturation period. The time courses of various physiological, biochemical, and structural changes of embryo and testa during seed maturation were analyzed in detail (dry and fresh mass changes, osmotic and water potential changes, respiration, DNA amplification by endomitosis, total ribosome and polysome formation, storage protein synthesis and accumulation, storage lipid accumulation). In addition to the final storage products protein and lipid, embryo and testa accumulate transiently large amounts of starch within the chloroplasts during early maturation. Concomitantly with the subsequent total breakdown of the starch, the plastids lose most of their internal structure and chlorophyll and shrink into proplastids, typical for the mature seed. At about 30 dap the seeds shift from a desiccation-sensitive to a desiccation-tolerant state and are able then to germinate rapidly upon drying and reimbibition. If isolated from the immature fruit and sown directly on water, the seeds demonstrate precocious germination from about 13 dap onwards. Young seeds (isolated ≦ 38 dap) germinate only after surpassing a lag-phase of several days (after-ripening) during which the embryo continues to accumulate storage protein and lipid at the expense of the surrounding seed tissues. We conclude from these results that the maturing seed represents a rather closed developmental system which is able to continue its development up to successful germination without any specific regulatory influence from the mother plant. Immature seeds are able to germinate without a preceding dehydration treatment, which means that partial or full desiccation does not serve as an environmental signal for reprogramming seed development from maturation to germination. Instead, it is argued that the water relations of the seed are a critical element in the control of maturation and germination: during maturation on the mother plant the embryo is subject to a considerable turgor pressure (of the order of 12 bar) accompanied by a low water potential (of the order of ?12 bar). This turgor permits maturation growth but is subcritical for germination growth. However, upon imbibition in water, the low water potential provides a driving force for a burst of water uptake overcoming the critical turgor threshold and thereby inducing germination.     

Seed Germination Traits of Loquat (<i>Eriobotrya japonica</i> Lindl.) as Affected by Various Pre-Sowing Treatments (Cutting of Cotyledons,Removal of Perisperm,Moist Chilling and/or Exogenous Application of Gibberellin)

The purpose of this study was to investigate the effects of various presowing treatments on the germinability (final germination percentage) and germination rate of loquat seeds in order to increase seedling production in nurseries(applied research) as well as provide answers for important physiological issuesrelated to loquat seeds and their seed coat (basic research). Three experimentswere carried out with various pre-sowing treatments. These treatments includedfull or partial removal of seed coat (perisperm), partial cutting of cotyledons aswell as moist chilling at 5°C for 13 days and/or soaking the seeds in water or250 ppm gibberellic acid (GA3) solution for 24 h. According to the results, cotyledons excision resulted in delayed germination, regardless of the presence orabsence of the seed coat in comparison with the decoated seeds that demonstratedthe highest germination rate amongst them. In addition, even the partial excisionof seed coats affected positively both the germinability and the germination rate,compared to the control-intact seeds. Furthermore, control-intact seeds had ahigher germination percentage when exposed to moist chilling independently ofthe application or not of gibberellin; while the combination of gibberellin application and moist chilling improved both the percentage and the rate of germinationof decoated seeds. In conclusion, the role of perisperm (seed coat) in the germination procedure of loquat seeds seems to be important, indicating the existence ofseed coat-imposed dormancy on loquat seeds. Finally, the existence of a mildendogenous embryo-dormancy on loquat is also discussed.