Leukamenin E调节拟南芥幼苗生长发育的模式及其机制

研究对映-贝壳杉烷型二萜化合物Leukamenin E对拟南芥种子萌发、下胚轴伸长以及根生长发育的作用模式,并探讨植物激素生长素和乙烯可能介导Leukamenin E影响拟南芥主根生长、侧根和根毛发育的初步机制。结果表明:Leukamenin E浓度在10~160μmol·L~(-1)范围对拟南芥种子的萌发率无显著影响,但高浓度Leukamenin E(80~160μmol·L-1)显著抑制种子的萌发速率。Leukamenin E对拟南芥幼苗根生长的抑制作用明显高于对下胚轴的抑制效应。进一步研究表明,Leukamenin E通过阻滞根尖细胞有丝分裂和细胞伸长进而抑制主根的生长,并能促进侧根提前发生并影响其形成数量,同时减少根毛密度及降低根毛长度。Leukamenin E联合乙烯利(乙烯释放剂)处理可阻止乙烯利单独使用对拟南芥幼苗根毛生长的促进作用,与Ag+(乙烯竞争抑制剂)联合乙烯利的作用效果相一致,表明Leukamenin E可能通过干扰根细胞乙烯途径而抑制根毛发育。流动注射化学发光分析和酶联免疫检测的结果发现,Leukamenin E显著上调拟南芥幼苗根组织中生长素(IAA)水平,表明生长素可能作为主要因子介导了Leukamenin E对拟南芥幼苗根生长发育的调节作用。     

蕨藻红素促进大豆插条不定根的形成

对蕨藻红素影响大豆下胚轴插条不定根形成的研究表明：蕨藻红素促进大豆插条不定根的形成,其最适浓度为0.5μmol·L^-1,最适处理时间为2d。0.5μmol·L^-1蕨藻红素处理大豆插条后,不定根诱导阶段（0～24h）的POD、CAT、IAAox活性较低;而不定根形成生长阶段（24～72h）的CAT和IAAox活性较高,POD活性低于未作处理的。试验推测蕨藻红素促进大豆插条不定根形成的生理基础可能与其影响POD、CAT和IAAox活性有关。     

H2O2在黄瓜和绿豆下胚轴不定根形成中的作用

以黄瓜和绿豆下胚轴插条为试验材料,研究了H2O2对不定根形成的诱导作用,以及在此过程中与IAA、NO的关系。结果表明,H2O2能促进不定根的形成,最佳浓度是100μmol/L;H2O2的清除剂———过氧化氢酶(CAT)抑制了IAA诱导的不定根形成,说明H2O2可能介导了IAA诱导不定根形成的过程;NO清除剂———PTIO能抑制H2O2诱导的不定根形成,表明NO在H2O2诱导不定根形成的过程中起介导作用。综合上述结果,推测在不定根形成的过程中可能存在以下关系:IAA首先诱导H2O2合成,H2O2升高后,再诱导NO产生,最终导致不定根生成。     

拟南芥CEO1基因在氯化镉诱导的氧化胁迫中的作用

以拟南芥ceo1、突变体为材料,研究CEO1（clone eight-one）在镉胁迫条件下作用的结果表明,与野生型植株相比,150μmol·L^-1的CdCl2处理10d后,拟南芥ceo1突变体表现为植株生长矮小,叶片卷曲发黄,根系短小。镉处理后,拟南芥突变体幼苗叶中H2O2的积累较多;镉处理1h后的突变体中抗坏血酸过氧化物酶（APX）活性明显上升,至2h时又开始下降,而镉处理2h后,野生型APX活性才开始增加。镉处理2h后的野生型的谷胱甘肽还原酶（GR）显著增加,而突变体无明显变化。两种类型拟南芥的超氧化物歧化酶（SOD）与过氧化氢酶（CAT）的活性没有明显差异。     

1-萘氨甲酰苯甲酸、外源IAA和GA3对拟南芥根的伸长和向重力性反应的影响

拟南芥幼苗用1-萘氨甲酰苯甲酸(NPA)、IAA和GA3处理后测定根的伸长和向重力性弯曲的结果表明,低浓度(0.001μmol·L-1)IAA和(0.01~1μmol·L-1)GA3促进根的伸长和向重力性弯曲,高浓度(0.01~10μmol·L-1)IAA和(10~100μmol·L-1)GA3的则相反。NPA在总体上是抑制根的伸长和向重力性弯曲,但低浓度(0.4μmol·L-1)的NPA有促进根伸长的趋势。低浓度的IAA和GA3均拮抗NPA对根伸长的影响,且低浓度的GA3对根伸长的促进作用并不依赖IAA。     

拟南芥MelAA抗性突变体的筛选和初步图位克隆分析

生长素是最重要的植物激素之一,参与了植物生长发育的各个方面。植物体内游离的IAA是生长素的主要活性形式,在IAA甲基转移酶1（IAMT1）的作用下,IAA可以转变为IAA甲酯（MelAA）。MelAA本身没有活性,在植物体内的MelAA酯解酶作用下可以重新转变为IAA。MelAA是非极性分子,能够在植物体内自由扩散。利用MelAA的这种特殊性质筛选突变体,可以分离到MelAA代谢途径或者IAA途径中新的成分。我们对拟南芥种子进行EMS诱变,通过观察黑暗下下胚轴的生长情况,筛选MelAA的抗性突变体。我们成功分离到了8株可能的抗性突变体,并对其中的一个Methyl-JAAresistant1（mir1）突变体进行了深入分析。MelAA抗性突变体的筛选将为进一步了解MelAA的代谢、IAA稳态调控和响应机理提供新的材料。     

拟南芥MeIAA抗性突变体的筛选和初步图位克隆分析

生长素是最重要的植物激素之一,参与了植物生长发育的各个方面。植物体内游离的IAA是生长素的主要活性形式,在IAA甲基转移酶1（IAMT1）的作用下,IAA可以转变为IAA甲酯（MelAA）。MelAA本身没有活性,在植物体内的MelAA酯解酶作用下可以重新转变为IAA。MelAA是非极性分子,能够在植物体内自由扩散。利用MelAA的这种特殊性质筛选突变体,可以分离到MelAA代谢途径或者IAA途径中新的成分。我们对拟南芥种子进行EMS诱变,通过观察黑暗下下胚轴的生长情况,筛选MelAA的抗性突变体。我们成功分离到了8株可能的抗性突变体,并对其中的一个Methyl-JAAresistant1（mir1）突变体进行了深入分析。MelAA抗性突变体的筛选将为进一步了解MelAA的代谢、IAA稳态调控和响应机理提供新的材料。     

GCR1和GCR2在N-酰基高丝氨酸内酯调节拟南芥根生长中的作用

N-酰基高丝氨酸内酯（AHLs）是革兰氏阴性细菌群体感应的信号分子。培养基中添加1μmol·L-13OC6-HSL和10μmol·L-13OC8-HSL可显著促进野生型拟南芥主根生长,但拟南芥G蛋白偶联受体GCR1和GCR2基因缺失突变体gcr1-1和gcr2-2对AHLs处理不敏感;实时荧光定量PCR分析显示,这2种AHLs的处理可以使拟南芥GCR1和GCR2基因表达量上调2～4倍。结果表明,G蛋白偶联受体GCR1和GCR2可能参与植物感应细菌信号进而做出根生长响应的信号转导。     

乙烯利、ACC、AOA和AgNO3对绿豆下胚轴插条不定根形成的作用

以绿豆下胚轴插条为实验材料,研究了乙烯利、ACC、AOA和AgNO,对其不定根形成的影响。结果表明：乙烯利和ACC能促进绿豆下胚轴插条的生根,最适浓度分别为50μmol／L和10μmol／L;AOA和AgNO3明显抑制不定根形成,随浓度增加,抑制作用增强。插条离体后24h内对ACC的促进作用和AOA的抑制作用敏感。插条在0-6h和18-24h用ACC处理,在0-2h和22-24h用50μmol／L乙烯利处理的生根效果好。乙烯在不定根形成的诱导期和起始晚期起促进作用。     

隐花素在生长素调控拟南芥下胚轴伸长中的作用分析

以拟南芥野生型(Col-4)和隐花素双突变体cry1cry2为材料,研究不同光照条件下不同浓度吲哚乙酸(IAA)和IAA极性运输抑制剂氨基酞氨酸(NPA)对幼苗下胚轴伸长的影响。结果显示,低浓度IAA(10-7mol/L)可促进连续白光和红光下cry1cry2幼苗下胚轴伸长,而连续蓝光下cry1cry2下胚轴的伸长则受到抑制。蓝光下相同浓度的NPA对cry1cry2幼苗下胚轴伸长的抑制程度比野生型要小。RT-PCR分析结果显示,瞬时蓝光处理时IAA合成关键酶基因IGPS以及生长素应答基因IAA1和IAA5在cry1cry2突变体中的转录水平比野生型中要高。这表明隐花素可能部分通过调节IAA合成和/或IAA极性运输,介导蓝光调控拟南芥下胚轴的伸长。     

Auxin and Ethylene-stimulated Adventitious Rooting in Relation to Tissue 9

We have previously shown that both endogenous auxin and ethylenepromote adventitious root formation in the hypocotyls of derootedsunflower (Helianthus annuus) seedlings. Experiments here showedthat promotive effects on rooting of the ethylene precursor,1-aminocyclopropane-l-carboxylic acid (ACC) and the ethylene-releasingcompound, ethephon (2-chloro-ethylphosphonic acid), dependedon the existence of cotyledons and apical bud (major sourcesof auxin) or the presence of exogenously applied indole-3-aceticacid (IAA). Ethephon, ACC, aminoethoxyvinylglycine (an inhibitorof ethylene biosynthesis), and silver thiosulphate (STS, aninhibitor of ethylene action), applied for a length of timethat significantly influenced adventitious rooting, showed noinhibitory effect on the basipetal transport of [³H]IAA. Theseregulators also had no effect on the metabolism of [³H]IAA andendogenous IAA levels measured by gas chromatography-mass spectrometry.ACC enhanced the rooting response of hypocotyls to exogenousIAA and decreased the inhibition of rooting by IAA transportinhibitor, N-1-naphthylphthalamic acid (NPA). STS reduced therooting response of hypocotyls to exogenous IAA and increasedthe inhibition of rooting by NPA. Exogenous auxins promotedethylene production in the rooting zone of the hypocotyls. Decapitationof the cuttings or application of NPA to the hypocotyl belowthe cotyledons did not alter ethylene production in the rootingzone, but greatly reduced the number of root primordia. We concludethat auxin is a primary controller of adventitious root formationin sunflower hypocotyls, while the effect of ethylene is mediatedby auxin. Key words: Auxin, ethylene, adventitious rooting, sunflower     

新型分裂素PBU对尾巨桉胚性愈伤组织诱导及植株再生的影响

以尾巨桉优良无性系无菌苗茎段为外植体,通过对噻唑基脲类新型分裂素（N-phenyl-N′-[6-（2-chlorobenzothiazol）-yl]urea,PBU）等多种不同浓度生长调节剂组合的优化,进行胚性愈伤组织诱导及植株再生研究。结果表明,在添加了2mg·L^-1PBU和0.05mg·L^-1IAA的改良MS培养基上,茎段外植体培养5d后愈伤组织诱导率达96%以上。将愈伤组织接种在添加1mg·L^-16-BA和0.05mg·L^-1NAA的MS培养基上,诱芽率达90.8%。随后在添加了0.8mg·L^-1PBU与0.05mg·L^-1IAA的1/2MS培养基上诱导芽伸长,用1/2MS培养基附加0.5mg·L^-1IBA诱导生根,移栽后得到完整再生植株。     

松潘乌头块根愈伤组织诱导及再生体系的建立

以野生松潘乌头块根为材料,进行愈伤组织诱导与植株再生培养。由于松潘乌头离体培养时,组织褐变严重,因此在愈伤组织诱导前须进行除褐培养,培养基以MS＋6-BA 1.0 mg·L^-1＋VC 300 mg·L^-1＋PVP 200 mg·L^-1效果较好,连续转移3次后褐变率显著降低到10%。适宜的愈伤组织诱导培养基为MS＋2,4-D 3.0 mg·L-1＋6-BA 2.0 mg·L^-1＋LH 500 mg·L^-1,诱导率100%;不定芽分化培养基为MS＋ZT 1.0 mg·L^-1＋6-BA 2.0 mg·L^-1＋NAA 0.5 mg·L^-1,分化率93%;不定芽增殖培养基为MS＋6-BA 2.0 mg·L^-1＋NAA 0.3 mg·L^-1,平均增殖倍数为6.0左右;生根培养基为1/2MS＋IAA 0.3 mg·L^-1＋VC 100 mg·L^-1（或PVP 300 mg·L^-1）,平均生根数10条左右,生根率为96%以上。将瓶苗移栽于森林土和蛭石以1：1（V/V）混合的基质中,生长良好,成活率达90%以上。     

不同株龄日本落叶松插穗的内源激素含量与生根的关系

研究了日本落叶松母株年龄、插穗内源激素含量与生根之间的关系,以及外源IBA对插穗内源激素含量的影响及其对插穗生根的促进作用。结果表明：不同株龄插穗生根性状及插穗茎和叶中激素含量差异均达极显著水平,叶中激素含量对插穗生根力没有直接影响;插穗茎中生根抑制激素（ABA）含量随株龄增长而增加,生根促进激素与抑制激素的比值（IAA＋GA＋ZR）/ABA却随株龄的增长而递减,与生根力随株龄的变化趋势一致,且该比值与生根性状紧密相关,因此可作为评价母株（无性系）生根力的指标;插后13～32d是插穗愈伤组织形成和不定根诱导的关键期,此期生根促进激素消耗量大,茎中含量大幅度降低,进入根伸长生长阶段,含量上升;外源IBA促进插穗生根的机制在于通过外源激素的刺激,在不定根诱导期,插穗茎中ABA含量大幅度降低,从而有利于不定根的发生和发育。     

Effect of abscisic acid on endogenous IAA, auxin protector levels and peroxidase activity during adventitious root initiation in Vigna radiata cuttings

Endogenous levels of free and conjugated IAA, auxin protectors (Prs) and peroxidase (PER) activity and their relation to adventitious root initiation (ARI) were investigated at the potential sites of adventitious rooting in relation to exogenous application of 250 μM ABA during the first 120 h after treatment. Cuttings from 7-day-old mung bean [Vigna radiata (L.) Wilcz.] seedlings were treated with 125, 250, and 500 μM ABA for 24 h. ABA significantly stimulated ARI but extremely inhibited epicotyl growth as compared to control. Free and conjugated IAA were measured by reversed-phase high performance liquid chromatography while Prs and PER activities were measured spectrophotometrically. The present results also indicate that endogenous free IAA levels peaked later in ABA-treated cuttings than that in control, suggesting that ABA extended the length of the induction phase of rooting process in treated cuttings and that might explain the significant delay of the appearance of roots at the treated cuttings. Higher level of IAA conjugates was found in ABA-treated cuttings than that in untreated ones. Pr level also peaked later in ABA-treated cuttings than that in control, indicating that ABA extended the period of Pr activity. An initial temporary decrease of PER activity was found in associating with high levels of free IAA and Prs during most of the primary events, while the opposite occurred during the secondary events of adventitious rooting process in both treated and untreated cuttings. Thus, ABA may stimulate ARI in mung bean Vigna radiata cuttings by regulating the concentration and /or activities of endogenous IAA, Prs, and PER activity in favor of inducing a large number of adventitious roots at their potential sites of adventitious rooting.     

Root Formation in Ethylene-Insensitive Plants

Experiments with ethylene-insensitive tomato (Lycopersicon esculentum) and petunia (Petunia x hybrida) plants were conducted to determine if normal or adventitious root formation is affected by ethylene insensitivity. Ethylene-insensitive Never ripe (NR) tomato plants produced more below-ground root mass but fewer above-ground adventitious roots than wild-type Pearson plants. Applied auxin (indole-3-butyric acid) increased adventitious root formation on vegetative stem cuttings of wild-type plants but had little or no effect on rooting of NR plants. Reduced adventitious root formation was also observed in ethylene-insensitive transgenic petunia plants. Applied 1-aminocyclopropane-1-carboxylic acid increased adventitious root formation on vegetative stem cuttings from NR and wild-type plants, but NR cuttings produced fewer adventitious roots than wild-type cuttings. These data suggest that the promotive effect of auxin on adventitious rooting is influenced by ethylene responsiveness. Seedling root growth of tomato in response to mechanical impedance was also influenced by ethylene sensitivity. Ninety-six percent of wild-type seedlings germinated and grown on sand for 7 d grew normal roots into the medium, whereas 47% of NR seedlings displayed elongated tap-roots, shortened hypocotyls, and did not penetrate the medium. These data indicate that ethylene has a critical role in various responses of roots to environmental stimuli.     

Ethylene and auxin-ethylene interaction in adventitious root formation in mung bean (Vigna radiata) cuttings

The role of ethylene in adventitious root formation and its involvement in auxin-induced rooting were investigated in cuttings ofVigna radiata (L.). Treatment with 30 M indole-3-acetic acid (IAA) for 24 h slightly inhibited rooting, whereas the same concentration of indole-3-butyric acid (IBA) significantly stimulated it. Ethylene derived from 1-aminocyclopropane-1-carboxylic acid (ACC) increased the number of adventitious roots but inhibited their emergence and elongation. Endogenous levels of ethylene, ACC, and malonyl-ACC (MACC) were initially higher in cuttings treated with IAA. This trend was quickly reversed, and cuttings, particularly hypocotyls, treated with IBA produced higher levels of ethylene and had more ACC and MACC during most of the rooting process. Aminoethoxyvinylglycine significantly inhibited rooting, but its inhibitory effect could not be reversed by ACC. The data suggest that the stimulating effect of IBA on rooting is closely associated with its induction of ACC and ethylene biosynthesis.     

楸树嫩枝扦插生根的主要影响因子分析

研究了插条的不同取材部位、不同激素组合以及不同扦插时间对4个类型（品种）楸树（Catalpa bungei C．A．Mey．）嫩枝插条生根的影响。结果显示,取楸树嫩枝的梢部与中部作为插条,扦插生根效果较好;用1．0g·L^-1 IBA和0．5g·L^-1 NAA混合溶液处理的插条生根效果最好,生根率可达45．43％;6月中旬是楸树嫩枝扦插的最适时期。4个楸树类型（品种）中,‘圆基长果楸’和‘豫楸1号’插条的生根能力较高,而‘金丝楸’的生根能力较差。     

基于均匀设计法优化三种槭树属植物高效快繁体系

以花楷械、青楷械和小楷械的嫩茎段为外植体,应用均匀设计法筛选最适合于嫩茎腋芽生长伸长同时生根的培养基．结果表明,最适合花楷械的培养基为：改良MS＋IAA0．10mg·L^-1＋GAa1．10mg·L^-1,再生率为98％;最适合青楷械的培养基为：改良MS＋IAA0．40mg·L^-1＋IBA0．10mg·L^-1＋NAA0．07mg·L^-1＋GA31．10mg·L^-1,再生率为96％;最适合小楷械的培养基为：改良MS＋IBA0．10mg·L^-1＋GA31．10mg·L^-1,再生率为94％．以再生植株的茎节为材料进行快繁的结果表明,在30-35d的一个培养周期内,增殖倍数达65以上．