8-甲氧基二氢血根碱化感潜能的评估

以莴苣幼苗为材料,检测了分离自细果角茴香的生物碱对莴苣幼苗根生长及根毛发育的影响。结果表明:50~200μmol·L-1浓度范围内,8-甲氧基二氢血根碱对莴苣幼苗根长显著抑制;10、20和30μmol·L-18-甲氧基二氢血根碱对莴苣幼苗根毛的长度和数量有显著的抑制作用,且抑制作用均表现了浓度依赖性。通过对莴苣根尖细胞有丝分裂研究发现,50μmol·L-1的8-甲氧基二氢血根碱能显著抑制根尖细胞的有丝分裂,而且莴苣幼苗净增值率与根尖细胞的有丝分裂之间呈正相关,证明8-甲氧基二氢血根碱主要通过抑制根尖细胞有丝分裂对莴苣根的生长产生影响。     

肉桂酸和咖啡酸对莴苣生长的化感作用及其机理研究

该研究以莴苣为受体植物,分析了酚酸类化感物质肉桂酸和咖啡酸对莴苣幼苗生长的活性效应及其作用机理,以揭示酚酸类化合物的化感作用机制。结果显示:(1)不同浓度的肉桂酸均对莴苣幼苗根长、茎长及鲜重产生明显的抑制作用,当肉桂酸的浓度为1 000μmol/L时其对莴苣幼苗根长、茎长及鲜重的抑制率分别达到了89%、74%和49%;咖啡酸对莴苣幼苗根长和茎长均表现出低浓度(0.1、1.0和10μmol/L)促进、高浓度(100和1 000μmol/L)抑制的活性作用模式,且高浓度下肉桂酸对幼苗生长的抑制作用明显强于咖啡酸。(2)较低浓度(0.1、1.0和10μmol/L)的肉桂酸和咖啡酸对莴苣根尖细胞活力均无明显影响;高浓度(100和1 000μmol/L)的肉桂酸和咖啡酸使莴苣根尖细胞的死亡数明显增加。(3)低浓度(0.1和1.0μmol/L)的肉桂酸和较低浓度(0.1、1.0和10μmol/L)的咖啡酸对莴苣根部的活性氧积累均无明显影响;当肉桂酸处理浓度大于10μmol/L及咖啡酸处理浓度大于100μmol/L时,随着浓度的升高莴苣根部活性氧的积累大量增加。研究表明,一定浓度的肉桂酸和咖啡酸均能够诱导莴苣体内活性氧的产生和积累,并降低幼苗根尖细胞的活力,进而影响莴苣幼苗的生长发育,且肉桂酸的生长抑制作用明显强于咖啡酸。     

绿原酸对莴苣生长的化感作用及其机理研究

酚酸类化合物是一类重要的化感物质,广泛存在于农作物等植物体内以及耕作土壤中,与植物的化感效应以及连作障碍密切相关。该研究以蔬菜类植物莴苣为受体,采用植物细胞和生理学方法,分析酚酸类化感物质绿原酸抑制莴苣生长的活性效应及其作用机理,以揭示绿原酸介导的化感作用及连作障碍机制。结果显示:(1)绿原酸对莴苣的根长、茎长以及鲜重等生长指标均表现出低浓度(0.1和1.0μmol/L)促进、高浓度(10、100和1 000μmol/L)抑制的活性作用模式,其在10μmol/L及以上浓度时对根长和鲜重具有显著抑制作用,但在各浓度下对莴苣茎长无显著影响。(2)绿原酸处理后,莴苣根尖细胞分裂指数明显下降,随处理浓度的升高,各分裂时期的细胞比例也显著降低,导致细胞分裂过程受阻。(3)较低浓度(0.1、1.0和10μmol/L)绿原酸对莴苣根尖细胞活力无明显影响,较高浓度绿原酸(100和1 000μmol/L)使莴苣根尖死细胞显著增多,根尖端绝大部分细胞失去活力。(4)DHE荧光染色显示,与对照相比,低浓度(0.1和1.0μmol/L)绿原酸对莴苣根部的活性氧积累无明显影响,当绿原酸处理浓度大于10μmol/L时,随处理浓度升高莴苣根部的活性氧积累明显大量增多。研究表明,绿原酸能够诱导莴苣体内活性氧产生并积累,从而导致莴苣细胞分裂受阻、细胞活力降低,最终影响莴苣幼苗的生长发育。     

血根碱通过下调TGF-β1/Smad通路抑制紫杉醇耐药卵巢癌细胞生长

培养紫杉醇耐药卵巢癌细胞A2780/Taxol,分为对照组与血根碱组,对照组不加血根碱,血根碱组应用不同浓度血根碱(0.67μmol/L、1.0μmol/L、2.0μmol/L)处理,应用MTT法、克隆形成、流式细胞检测和Western blot等实验方法检测血根碱对A2780/Taxol细胞增殖、凋亡、周期的影响及Bax、TGF-β1、Smad3蛋白的表达情况。结果显示,2.0μmol/L浓度的血根碱可显著抑制A2780/Taxol细胞增殖,与对照组相比,Bax表达显著上调,TGF-β1和Smad3蛋白表达水平明显下调(P0.05)。血根碱通过下调TGF-β1/Smad通路,促进细胞凋亡而抑制紫杉A2780/Taxol细胞生长。     

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。     

Ca2 +对小麦种根及其根毛生长发育的影响

低浓度的CaCl2对小麦种根生长、根毛发生和生长无明显影响,高浓度的CaCl2(0.1 mol/L)对种根和根毛生长有抑制作用,但不影响根毛的发生。Ca2+专一性整合剂EGTA抑制种根生长和根毛的发生及生长,添加一定浓度的外源CaCl2,这种抑制作用可被消除。CaM抑制剂TFP(三氟拉嗪)和CPZ(氯丙嗪)对种根生长、根毛发生和生长均有抑制作用,添加外源CaM可减弱或消除这种抑制作用。     

一氧化氮对盐胁迫下小麦幼苗根生长和氧化损伤的影响

0.05和0.10 mmol/L一氧化氮(NO)供体硝普钠(sodium mtropmsside,SNP)处理明显减轻NaCl浓度为150 mmo1/L左右的盐胁迫对小麦幼苗根生长的抑制效应,其中0.05mmol/L的SNP效果最明显;0.30mmol/L以上的SNP处理对根抑制无明显缓解作用;当NaCl浓度大于300 mmol/L时,各种浓度的SNP均不能减轻盐胁迫对根生长的抑制.以N O清除剂血红蛋白(hemoglobin,Hb)以及NOx-,K3Fe(CN)6等为对照,观察到0.05 mmol/L的SNP能不同程度地提高150mmo/L盐胁迫下小麦幼苗根尖细胞中超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(ascorbateperoxidase,APX)活性,明显降低MDA、H2O2和O2-.的积累,阻断盐胁迫诱导的根尖细胞DNA片段化,表明NO能有效缓解盐胁迫引起的小麦幼苗根尖细胞的氧化损伤.     

Cd2+对蚕豆根生长发育的影响

目的探明Cd^2＋对蚕豆根生长发育的影响及其规律,为培育耐Cd^2＋新品种提供一定的科学依据。方法以不同浓度的Cd^2＋处理蚕豆根,然后在不同时间检测其色泽、弯曲程度和长度变化,同时利用改良的苯酚品红染色,在显微镜下观察根尖细胞的有丝分裂。结果当Cd^2＋浓度〈10μmol／L时,它能促进根的生长和细胞有丝分裂,但对根的色泽和弯曲程度的影响不明显。在Cd^2＋的浓度〉10μmol／L后,则逐渐使根色泽加深,弯曲程度增大,细胞有丝分裂指数下降,生长减慢。结论Cd^2＋对蚕豆根生长发育有影响,其影响的程度与Cd^2＋的浓度和处理时间有关。     

外源钙对镉胁迫下南美蟛蜞菊毛状根生长、抗氧化酶活性和镉吸收的缓解效应

为了探讨外源钙对重金属镉(Cd)缓解南美蟛蜞菊Wedelia trilobata毛状根毒害的生理机理,采用溶液培养法研究了重金属Cd单独及其与Ca组合对南美蟛蜞菊毛状根生长、抗氧化酶超氧化物岐化酶(SOD)和过氧化物酶(POD)活性及对Cd2+吸收的影响。结果表明,Cd≤50μmol/L时促进毛状根生长;高于100μmol/LCd则抑制其生长,使其侧根短小,根尖变褐或变黑。与对照相比,不同浓度Cd培养的毛状根POD活性、SOD活性和MDA含量都比对照明显提高,但高于100μmol/L Cd培养的毛状根可溶性蛋白含量均比对照降低。与仅添加200μmol/L或300μmol/L Cd的毛状根相比,Cd和10~30 mmol/L Ca组合培养可促进毛状根生长,使其主、侧根变粗;提高其可溶性蛋白含量;降低其MDA含量、POD活性及SOD活性。原子吸收分光光度法测定结果表明,南美蟛蜞菊毛状根能吸收和吸附重金属Cd2+,当Cd2+浓度为100μmol/L时毛状根对Cd2+的吸收量最大,而Cd2+浓度为300μmol/L时毛状根对Cd2+的吸附量最大。外源加入10~30 mmol/L Ca2+可显著减少毛状根对Cd2+的吸收和吸附,并可调节其抗氧化酶活性,降低其膜脂过氧化水平而解除重金属镉对毛状根生长的抑制或毒害。     

盐胁迫对盐生植物黄花补血草种子萌发和幼苗生长的影响

盐生植物黄花补血草广泛分布于我国西北地区、东北西部以及华北北部,对改良盐碱土壤具有重要的生态作用。以黄花补血草(Limonium aureum(L.)Hill)为材料,研究分析了不同浓度NaCl胁迫对其种子萌发和幼苗生长产生的抑制效应及作用机制。结果表明:低浓度NaCl(25 mmol/L和50 mmol/L)处理不影响黄花补血草种子萌发和幼苗生长,25 mmol/L NaCl甚至促进了根生长,而高浓度NaCl(100 mmol/L和150 mmol/L)处理明显抑制种子萌发及幼苗生长。利用荧光探针的检测结果表明,NaCl处理的幼苗根中过氧化氢(H2O2)和一氧化氮(NO)含量明显高于对照水平。碘化丙啶(PI)染色结合激光共聚焦显微镜观察及检测相对电导率结果显示,高浓度NaCl处理抑制了幼苗根尖伸长区细胞的伸长生长,增加了细胞膜的通透性,对根细胞造成了明显的伤害。此外,高浓度NaCl处理诱导叶片丙二醛(MDA)含量显著升高。以上结果说明,黄花补血草对低浓度的盐具有一定的耐盐性,但高浓度盐降低了种子的萌发率,使幼苗根中H2O2产生增加,抑制根尖伸长区细胞的伸长生长,对根、叶造成明显氧化损伤,从而抑制黄花补血草幼苗的生长。     

Regulation of Root Growth in Lactuca sativa L. Seedlings by the Ent-Kaurane Diterpenoid Epinodosin

Epinodosin, an ent-kaurane diterpenoid isolated from Isodon japonica var. galaucocalyx, had a biphasic, dose-dependent effect on root growth and a strong inhibitory effect on root hair development in Lactuca sativa L. seedlings. Lower levels of epinodosin (25–100 μM) significantly promoted root growth, but higher concentrations (150–200 μM), by contrast, had inhibitory effects. In addition, all of the tested concentrations (20–80 μM) inhibited root hair development of lettuce seedlings in a dose-dependent manner. Further investigations on the underlying mechanism revealed that the promotion effect of epinodosin (25–100 μM) resulted from increasing the cell length in the mature region and enhancing the mitotic activity of meristematic cells in lettuce seedling root tips. On the other hand, epinodosin at higher concentrations inhibited root growth by strongly affecting both the cell length in the mature region and the division of meristematic cells. Comet assay analysis demonstrated that the decrease of mitotic activity of root meristematic cells was due to DNA damage induced by higher levels of epinodosin.     

二氧化硫衍生物对蚕豆幼苗生长和细胞周期的影响

研究SO₂体内衍生物NaHSO₃与Na₂SO₃(1:3,mmol/L)对蚕豆幼苗生长和细胞分裂的影响。结果表明:SO₂衍生物(浓度在0~30mmol/L)对幼苗生长的抑制作用具有剂量效应和时间效应关系,短时间处理效应不明显,处理48h后蚕豆幼根生长抑制,168h后幼苗根上部分长度(芽长)表现生长抑制,根长和芽长与处理浓度间呈负线性相关。SO₂衍生物处理12~36h,导致根尖细胞分裂指数下降,根尖中前期细胞减少,间期、后期和末期细胞增多,表明SO₂衍生物能够阻止细胞进入分裂态,延长分裂过程,这可能是SO₂衍生物处理组根尖细胞分裂指数降低,幼苗生长抑制的主要原因。     

The natural compound benzoxazolin-2(3H)-one selectively retards cell cycle in lettuce root meristems

Benzoxazolin-2(3H)-one (BOA) is a natural plant product that is phytotoxic to target plant species, inhibiting germination and growth and causing oxidative damage. We investigated its effects on the root meristems of seedlings of lettuce (Lactuca sativa) by means of light and transmission electron microscopy, flow cytometry, and conventional determination of mitotic index. Flow cytometry analyses and mitotic index showed a retard of cell cycle in BOA-treated meristems with selective activity at G2/M checkpoint.     

Isolation and identification of a potent allelopathic substance in rice root exudates

A search for growth inhibitors in rice root exudates was undertaken in order to clarify the allelopathic system in rice ( Oryza sativa L.). Rice seedlings inhibited the growth of cress ( Lepidium sativum L.) and lettuce ( Lactuca sativa L.) seedlings when the cress and lettuce were grown with rice seedlings. The putative compound causing the inhibitory effect of rice seedlings was isolated from their culture solution, and the chemical structure of the inhibitor was determined by spectral data as momilactone B. Momilactone B inhibited the growth of cress and lettuce seedlings at concentrations greater than 3 and 30 µ M , respectively. The concentration of momilactone B was 3.4 and 1.1 nmol per seedling in the culture solutions of husked and non-husked rice seedlings, respectively. These results suggest that rice seedlings may release momilactone B into the environment and the stress caused by the husk-treatment may increase the amount of momilactone B released. Thus, momilactone B may play an important role in rice allelopathy.     

Cd-K双重处理对水稻幼苗生长和Cd吸收转运的影响及相关转运通道分析

以水稻( Oryza sativa Linn.)高 Cd 积累品种‘T 优705’(‘T You 705’)和低 Cd 积累品种‘湘早籼24’(‘Xiangzaoxian 24’)为实验材料,采用水培法对不同浓度Cd(0.0和2.7μmol·L-1 Cd)和K(0、30和60 mmol·L-1 K)处理条件下2个品种幼苗的相对生长量、根系和地上部的Cd含量及其亚细胞分布特征进行了比较,并分析了添加离子通道活性抑制剂TEA和LaCl3后幼苗根系和地上部的Cd和K含量;在此基础上,比较了NSCCs(非选择性阳离子通道)和K专性通道对2个品种幼苗根系和地上部Cd和K吸收贡献率的影响。结果表明：与Cd单一处理组(2.7μmol·L-1 Cd)相比, Cd-K双重处理组(2.7μmol·L-1 Cd-30 mmol·L-1 K和2.7μmol·L-1 Cd-60 mmol·L-1 K)2个品种幼苗的相对生长量显著提高,而幼苗根系和地上部的Cd含量显著下降;随K浓度的提高,2个品种幼苗根系细胞壁和细胞液中的Cd含量显著下降,但细胞壁中Cd含量的分配比例增大而细胞液中Cd含量的分配比例则减小。在含2.7μmol·L-1 Cd和30 mmol·L-1 K的培养液中分别添加5 mmol·L-1 TEA或0.2 mmol·L-1 LaCl3后,2个品种幼苗根系和地上部的Cd和K含量均显著下降,其中,LaCl3处理组的根系Cd含量降幅高于TEA处理组,但LaCl3处理组的根系K含量降幅则低于TEA组。 NSCCs对品种‘T优705’幼苗根系和地上部Cd吸收的贡献率显著低于品种‘湘早籼24’幼苗,而K专性通道对品种‘T优705’幼苗根系K吸收和地上部Cd吸收的贡献率则显著低于品种‘湘早籼24’幼苗。研究结果显示：添加外源K可缓解Cd对水稻幼苗生长的抑制作用,并通过提高细胞壁与Cd的结合能力来降低细胞液中Cd的积累,以此减弱幼苗对Cd的吸收和转运能力;幼苗体内的K和Cd均可通过K专性通道和NSCCs转运,其中,K吸收和转运主要通过K专性通道完成,而Cd吸收和转运主要通过NSCCs完成。此外,品种‘T优705’可能具有多种离子通道参与Cd的吸收和转运,而品种‘湘早籼24’主要依赖NSCCs参与Cd的吸收和转运,且后者对K的吸收和积累强于前者。     

Inhibition of root growth by narciclasine is caused by DNA damage-induced cell cycle arrest in lettuce seedlings

Narciclasine (NCS) is an Amaryllidaceae alkaloid isolated from Narcissus tazetta bulbs. Its phytotoxic effects on plant growth were examined in lettuce (Lactuca sativa L.) seedlings. Results showed that high concentrations (0.5–5 μM) of NCS restricted the growth of lettuce roots in a dose-dependent manner. In NCS-treated lettuce seedlings, the following changes were detected: reduction of mitotic cells and cell elongation in the mature region, inhibition of proliferation of meristematic cells, and cell cycle. Moreover, comet assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay indicated that higher levels NCS (0.5–5 μM) induced DNA damage in root cells of lettuce. The decrease in meristematic cells and increase in DNA damage signals in lettuce roots in responses to NCS are in a dose-dependent manner. NCS-induced reactive oxygen species accumulation may explain an increase in DNA damage in lettuce roots. Thus, the restraint of root growth is due to cell cycle arrest which is caused by NCS-induced DNA damage. In addition, it was also found that NCS (0.5–5 μM) inhibited the root hair development of lettuce seedlings. Further investigations on the underlying mechanism revealed that both auxin and ethylene signaling pathways are involved in the response of root hairs to NCS.     

Evaluation of cytological effects of Zn2+ in relation to germination and root growth of Nigella sativa L. and Triticum aestivum L

The effects of different treatments with zinc sulfate (Zn(2+)) on the cytology and growth of Nigella sativa and Triticum aestivum were investigated. Five concentrations of zinc sulfate ranging from 5 to 25mg/l were applied for 6, 12, 18, and 24h. The treatments reduced the germination percentages of N. sativa seeds and T. aestivum grains and inhibited the root growth of both plants. Concentrations higher than 25mg/l of Zn(2+) applied for 24h were toxic for both plants. The non-lethal concentrations of Zn(2+) showed an inhibitory effect on cell division in root tips of both plants and caused a decrease in their mitotic index values. The reduction in MI in root tips of T. aestivum was more evident than that of N. sativa. All treatments changed the frequency of mitotic phases as compared with the control values. The total percentage of abnormalities in N. saliva was more than that in T. aestivum. Zn(2+) treatments produced a number of mitotic abnormalities in dividing cells in root tips of both plants resulting from its action on the spindle apparatus such as C-metaphases, lagging chromosomes and multipolar anaphases and telophases. Also, Zn(2+) induced vacuolated nuclei and irregular prophases. The induction of chromosomal stickiness and chromosomal aberrations such as bridges and breaks indicates its action on the chromosome. These abnormalities (chromosome breaks and chromosomal bridges at ana-telophases) indicate true clastogenic potential of the ions tested.     

Identification of two phytotoxins, blumenol A and grasshopper ketone, in the allelopathic Japanese rice variety Awaakamai

Aqueous methanol extracts of the traditional rice (Oryza sativa) variety Awaakamai, which is known to have the greatest allelopathic activity among Japanese traditional rice varieties, inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), timothy (Phleum pratense), Digitaria sanguinalis, Lolium multiflorum and Echinochloa crus-galli. Increasing the extract concentration increased the inhibition, suggesting that the extract of Awaakamai contains growth inhibitory substances. The extract of Awaakamai was purified and two main growth inhibitory substances were isolated and determined by spectral data as blumenol A and grasshopper ketone. Blumenol A and grasshopper ketone, respectively, inhibited the growth of cress shoots and roots at concentrations greater than 10 and 30 μmol/L. The concentrations required for 50% growth inhibition on cress roots and shoots were 84 and 27 μmol/L, respectively, for blumenol A, and 185 and 76 μmol/L, respectively, for grasshopper ketone. These results suggest that blumenol A and grasshopper ketone may contribute to the growth inhibitory effect of Awaakamai and may play an important role in the allelopathy of Awaakamai.     

二氧化硫衍生物对玉米种子萌发、幼苗生长和细胞分裂的影响

研究3种二氧化硫衍生物硫酸钠、亚硫酸钠和亚硫酸氢钠对玉米种子萌发、幼苗生长和细胞分裂的影响。结果表明,一定浓度(0.1 mmol·L^-1)的硫酸盐和亚硫酸盐处理液能促进玉米种子萌发和幼苗生长,但浓度超过2.5 mmol·L^-1时能抑制种子萌发和幼苗生长。较高浓度的3种盐溶液对根尖分生区细胞的分裂具有抑制作用,并导致其中的部分细胞异常,出现细胞核固缩,甚至产生质壁分离。3种二氧化硫衍生物的毒性排序为：亚硫酸氢钠＞亚硫酸钠＞硫酸钠。     

曼陀罗叶水浸液对大豆幼根生长及细胞分裂的影响

以曼陀罗叶干粉为供体,大豆种子为受体,用室内培养皿法研究了曼陀罗叶水浸液化感胁迫对大豆种子萌发、幼根生长、根毛发育和根尖细胞分裂的影响。结果表明:各试验浓度的曼陀罗叶干粉水浸提液均抑制了大豆种子的萌发以及幼根和侧根的生长,且幼根生长随胁迫浓度的增加呈现逐渐缩短变粗变褐的趋势;化感胁迫还使根尖分生区细胞的染色体畸变和微核高频率发生。根毛发生和根尖细胞的分裂对化感胁迫都表现出"低促高抑"的响应,即轻度胁迫能显著促进根毛的生长并提高根尖细胞的分裂指数,而高度胁迫对根毛的生长有极显著的抑制作用,且使根尖细胞的分裂指数显著下降。