In-vitro germination and growth of lily pollen tubes is affected by protein phosphatase inhibitors

Inhibitors of type-2A protein phosphatase (PPase-2A), calyculin A (cal A) and okadaic acid (OA), inhibit pollen grain germination and growth of pollen tubes of Lilium longiflorum Thunb. at nanomolar concentrations. Half-maximal inhibition of cytoplasmic PPase-2A activity was below 0.1 nM for cal A and at 0.7 nM for OA. Other protein phosphatase inhibitors (tautomycin, cypermethrin, and dephostatin) were less effective. The OA- and cal A-sensitive as well as dephostatin-sensitive PPase activity in the cytoplasm did not change during germination and growth of pollen tubes. Addition of cal A and OA disturbed the direction of pollen tube growth and the distribution of cytoplasmic organelles and caused cell wall thickenings as observed by light and electron microscopy. Inhibition of PPase-2A caused multiple effects at the cellular level, cytoskeletal elements being a putative target of PPase-2A activity. Received: 30 March 1998 / Accepted: 6 July 1998     

钾对兰州百合鳞茎中多酚类物质积累代谢及其抗氧化活性的影响

为探究施钾对兰州百合鳞茎中多酚类物质的积累、抗氧化能力及差异代谢物的影响,该研究以兰州百合鳞茎为试材,通过固定氮素(N)和磷素(P)用量,设置不同钾(K)浓度处理,即K_(0)(不施肥)、K_(1)(447.6 mg·L^(-1))、K_(2)(671.4 mg·L^(-1))、K_(3)(895.2 mg·L^(-1)),采用福林-肖卡法、溴甲酚绿比色法、香草醛比色法、DPPH法、铜离子还原能力(CUPRAC)法测定不同K浓度处理下兰州百合鳞茎中多酚类物质含量及其抗氧化活性,并采用LC-MS法分析多酚类物质的差异代谢物,并进行差异代谢物筛选,功能注释及富集分析,为兰州百合的优质栽培提供理论依据。结果表明:(1)不同K浓度处理下兰州百合鳞茎中多酚类物质的含量及其抗氧化活性存在显著差异(P<0.05),与K_(0)相比,K_(1)、K_(2)、K_(3)均能促进鳞茎多酚类物质的积累及其抗氧化能力的提高,其中以K_(2)(671.4 mg·L^(-1))效果最佳。(2)相关性分析表明,兰州百合鳞茎多酚类物质含量与抗氧化活性指标呈极显著(P<0.01)相关关系,相关系数为0.451~0.959。(3)K_(0)、K_(2)浓度处理下兰州百合鳞茎中存在89种多酚类及相关化合物,其中52种相对含量显著上调,37种相对含量显著下调,且显著富集到黄酮类及苯丙类化合物生物合成的通路上。研究认为,兰州百合的最佳施钾量(671.4 mg·L^(-1))能有效促进鳞茎中多酚类物质的积累并提高其抗氧化能力。     

兰州百合组培鳞茎发育研究

该研究以兰州百合商品种球鳞片为外植体材料,通过组织培养诱导丛生芽萌发及高频增殖,再以丛生芽为材料诱导其发育形成小鳞茎,调节培养基对小鳞茎进行膨大发育培养,最终形成促进兰州百合组培鳞茎膨大发育的“三步”组培培养技术路线;对发育过程中形成的丛生芽、小鳞茎及膨大鳞茎进行淀粉含量测定与生长特征参数统计,分析各步培养对鳞茎形成发育过程中淀粉含量与形态变化的影响。结果表明：所建立的“三步”培养方案培育出的组培鳞茎直径、重量与鳞片数分别为1.66 cm、2.48 g和26.33片,有效地促进了鳞茎的膨大,并能诱导鳞茎主茎杆的形成发育;在培养进程中其淀粉含量呈现逐步增加的趋势,这表明与鳞茎膨大发育正相关,同时鳞茎大小、重量及鳞片数三者也表现为正相关性;当鳞茎所含鳞片数在26片以上时,其生长点易发育形成主茎杆。该文研究了兰州百合组培鳞茎的形成与膨大发育技术,所研发的“三步”培养组成的鳞茎膨大发育组培技术有效地促进了鳞茎的膨大发育,而膨大发育的鳞茎能有效地缩短田间生长周期,从时间上提高百合生产量,同时为实现兰州百合膨大的鳞茎种球规模化生产提供技术支撑。     

甜椒花药培养及再生植株技术体系的研究

为建立甜椒(Capsicum annuum var.grossum)花药培养及再生植株技术体系,对影响花药胚状体诱导和分化的因素进行了研究。结果表明,培养基组成对胚状体诱导率的影响以NAA基本培养基椰乳KT,最佳胚状体诱导培养基为NTH+0.1 mg L–1 NAA+10%椰乳+1 mg L–1 KT+50μmol L–1 Ag NO3+30 g L–1蔗糖+5 g L–1琼脂+2 g L–1活性炭。花药经过24 h低温预处理和8 d高温预培养后,胚状体诱导率可达23.38%。植物生长调节剂对胚状体出芽率的影响为6-BANAAIAA,最佳胚状体分化培养基为NTH+1 mg L–1 6-BA+0.3 mg L–1 NAA+0.1 mg L–1 IAA+30 g L–1蔗糖+5 g L–1琼脂。胚芽转入1/2MS+0.5 mg L–1 IBA+30 g L–1蔗糖+5 g L–1琼脂培养基后,生根率可达92.5%。     

Second-messenger-induced signalling events in pollen tubes of Papaver rhoeas

A role for cytosolic free Ca²⁺ (Ca²⁺_i) in the regulation of growth of Papaver rhoeas pollen tubes during the self-incompatibility response has recently been demonstrated [Franklin-Tong et al. Plant J. 4:163–177 (1993); Franklin-Tong et al. Plant J. 8:299–307 (1995); Franklin-Tong et al. submitted to Plant J.]. We have investigated the possibility that Ca²⁺_i is more generally involved in the regulation of pollen tube growth using confocal laser scanning microscopy (CLSM). Data obtained using Ca²⁺ imaging, in conjunction with photolytic release of caged inositol 1,4,5-trisphosphate [Ins(1,4,5)P₃], point to a central role of the phosphoinositide signal transduction pathway in the control of Ca²⁺ fluxes and control of pollen tube growth. These experiments further revealed that increases in cytosolic levels of Ins(1,4,5)P₃ resulted in the formation of distinct Ca²⁺ waves. Experiments using the pharmacological agents heparin, neomycin and mastoparan further indicated that Ca²⁺ waves are propagated, at least in part, by Ins(1,4,5)P₃-induced Ca²⁺ release rather than by simple diffusion or by “classic” Ca²⁺-induced Ca²⁺ release mechanisms. We also have data which suggest that Ca²⁺ waves and oscillations may be induced by photolytic release of caged Ca²⁺. Ratio-imaging has enabled us to identify an apical oscillating Ca²⁺ gradient in growing pollen tubes, which may regulate normal pollen tube growth. We also present evidence for the involvement of Ca²⁺ waves in mediating the self-incompatibility response. Our data suggest that changes in Ca²⁺_i and alterations in growth rate/patterns are likely to be closely correlated and may be causally linked to events such as Ca²⁺-induced, or Ins(1,4,5)P₃-induced wave formation and apical Ca²⁺ oscillations.Presented at the 1997 SEB Annual Meeting: Interactive MultiMedia Biology - Experimental Biology Online Symposium, Canterbury, 7-11 April     

南方红豆杉水浸提液对喜树种子发芽和幼苗生长的化感作用

化感作用是影响人工混交林种间关系的重要因素之一。已有研究表明：喜树南方红豆杉混交对喜树生长有明显促进作用,并从混交改善混交林地微气候角度解释了这种促进作用,但未从种间化感作用角度探讨这种作用。为了探究南方红豆杉是否对喜树具有潜在的化感促进作用,从而更全面了解喜树南方红豆杉混交林种间关系,考察了不同浓度（25、50 g/L和100 g/L）的南方红豆杉（Taxus chinensis var.mairei）鲜叶、凋落叶、枝和根水浸提液对喜树（Camptotheca acuminata）种子发芽和幼苗生长的影响。结果表明：（1）南方红豆杉凋落叶浸提液对喜树种子发芽和幼苗生长无显著影响（P>0.05）,而鲜叶、枝和根浸提液对喜树发芽和幼苗生长均具有不同程度的促进作用（P<0.05）,且作用强度大体与浓度呈正相关;（2）100 g/L的南方红豆杉鲜叶、枝和根浸提液浸泡的喜树种子,其发芽率比对照组分别提高8.1%、14.9%和25.6%;（3）南方红豆杉鲜叶浸提液只有在高浓度（100 g/L）时,对喜树幼苗基径生长具有促进作用（P<0.05）,而对其株高、全株干重和净光合速率无显著影响;南方红豆杉根和枝浸提液对喜树幼苗株高、基茎、干重和净光合速率均具有促进作用（P<0.05）,与对照组相比,100 g/L的根和枝浸提液浇灌喜树幼苗,可以使喜树幼苗株高分别提高14.2%和8.4%,基径分别提高19.0%和15.3%,干重分别提高23.1%和15.9%,净光合速率分别提高11.6%和6.1%。研究结果表明,在喜树南方红豆杉混交林中,南方红豆杉对喜树的正向化感作用可能是促进喜树生长的重要因素之一。     

Ce^3+和La^3+对人工老化沙葱种子活力及生理特性的影响

以未老化和人工老化后的沙葱(Allium mongolicum Regel.)种子为材料,采用氯化铈(Ce3+)和氯化镧(La3+)浸种,测定种子萌发和生理指标,探讨Ce3+和La3+浸种对种子萌发、老化种子活力和生理特性的影响。结果显示:(1)在老化0~5 h时,Ce3+和La3+处理可显著促进沙葱种子萌发,提高种子活力;在老化5 h后,Ce3+和La3+处理对种子萌发无明显促进作用。(2)在老化0~15 h时,Ce3+和La3+处理的沙葱种子中抗氧化酶活性和抗坏血酸(AsA)含量提高,其超氧阴离子自由基(O2-·)产生速率、过氧化氢(H2O2)含量和丙二醛(MDA)含量显著降低;在老化15 h后,Ce3+和La3+处理的种子抗氧化酶活性提高、AsA含量降低,O2-·产生速率和MDA含量提高。(3)在老化5 h时,沙葱种子呼吸速率发生跃变达到最大,Ce3+和La3+处理显著降低了种子呼吸速率。(4)Ce3+和La3+处理在老化0~5 h时提高了沙葱种子超弱发光(UWL)强度,但在老化5 h后沙葱种子的UWL强度降低。研究认为,在沙葱种子人工老化初期,Ce3+和La3+浸种处理可以诱导增强种子抗氧化酶活性和提高AsA含量,有效清除因老化产生积累的过量活性氧(ROS),减轻过氧化伤害,提高种子活力;种子老化中后期,其内部ROS产生与清除系统发生紊乱,加剧了ROS对种子结构的损伤,Ce3+和La3+浸种处理的缓解效应丧失。     

Conidial germination and germ tube elongation of Phomopsis amaranthicola and Microsphaeropsis amaranthi on leaf surfaces of seven Amaranthus species: Implications for biological control

Microsphaeropsis amaranthi and Phomopsis amaranthicola are potential biological control agents for several Amaranthus species. In an effort to understand the initial infection processes with these pathogens, a study was conducted of the conidial germination and germ tube length (μm) on the weed leaf surfaces at 21 °C and 28 °C. Weeds included Amaranthus rudis, A. palmeri, A. powellii, A. retroflexus, A. spinosus, A. hybridus, and A. albus. For P. amaranthicola, conidial germination and germ tube length varied among the seven weed species at both temperatures, while for M. amaranthi the differences in germ tube lengths were significant among weed species only at 21 °C. While the conidia of M. amaranthi and P. amaranthicola germinated on the leaf surfaces of all seven weed species, temperature appeared to impact the number and length of germ tubes on the leaf surfaces. The percentage of germinated conidia and the length of germ tubes at both temperatures were often greater for M. amaranthi than for P. amaranthicola. In order for the fungal pathogen to successfully infect and kill a weedy host, conidia must germinate and form a germ tube, two processes that vary with host species and temperature for M. amaranthi and P. amaranthicola. The extent to which successive infection processes, e.g., penetration, invasion and colonization, contribute to host specificity warrants study.     

Cytochemical localization of cellulase activity in pollen mother cells of david lily during meiotic prophase I and its relation to secondary formation of plasmodesmata

Summary Cellulase activity was localized at the ultrastructural level in pollen mother cells (PMCs) of David lily [Lilium davidii var.willmottiae (Wilson) Roffill] at different stages of meiotic prophase I. The enzyme was observed to appear at the early leptotene stage and reached its highest level at the subsequent zygotene stage, and its subcellular distribution revealed by the presence of electron-dense deposits of reaction product was found to be restricted exclusively to the endoplasmic reticulum (ER), the vesicles derived from that, and the cell wall, especially at the sites of secondary plasmodesmata and cytoplasmic channels where the wall was being digested. Other cytoplasmic organelles, such as dictyosomes and Golgi vesicles, lacked such deposits of reaction product. After zygotene the enzyme activity decreased abruptly, and at the pachytene stage only very few deposits could be observed in the cell wall. Our results indicate that cellulase is synthesized on rough ER and secreted directly via the smooth ER and ER-derived vesicles into the cell wall by exocytosis, where it brings about local wall breakdown, leading to the secondary formation of plasmodesmata and cytoplasmic channels.     

A23187和EGTA对光周期诱导菊花成花及其过程中叶片Ca2+分布和碳水化合物的影响

以切花菊品种‘神马’为试材,研究光周期诱导菊花成花过程中Ca²⁺载体A23187和Ca²⁺螯合剂EGTA处理对花芽分化及其过程中叶片Ca²⁺分布和蔗糖、可溶性糖及淀粉含量变化的影响.结果表明：对照叶片Ca²⁺含量在花芽未分化期（Ⅰ）处于较低水平,而在花芽分化启动期（Ⅱ）迅速增加并达到高峰,之后下降;Ca²⁺亚细胞定位表明,在未分化期（Ⅰ）Ca²⁺沉淀主要分布在液泡、细胞壁和细胞间隙中,细胞质内较少,而在花芽分化启动期（Ⅱ）细胞质内积累大量的Ca²⁺沉淀.A23187处理的菊花花芽分化开始和结束时间比对照分别提前2 d和3 d,叶片Ca²⁺含量比对照显著增加;EGTA处理的叶片Ca²⁺含量比对照显著减少,花芽分化开始和结束时间分别比对照推迟4 d和8 d;A23187和EGTA处理的叶片Ca²⁺在花芽分化启动期（Ⅱ）均向细胞质流入并密集.A23187处理的蔗糖和可溶性糖含量在处理2 d时达到峰值,比对照达到峰值的时间提前2 d,与Ca²⁺达到峰值的时间一致,而EGTA处理的蔗糖和可溶性糖含量在处理2 d时没有明显变化,8 d时才迅速增加达到峰值,即所有处理的蔗糖、可溶性总糖含量在花芽分化启动期（Ⅱ）均增加并达到高峰,之后有所减少,但其在整个花芽分化过程均高于光周期诱导前的含量;对照和A23187处理的淀粉含量在处理2 d时开始减少,而EGTA则在处理8 d后开始减少,至花芽分化结束所有处理的淀粉含量均保持较低水平（低于诱导前）.表明Ca²⁺碳水化合物参与了光周期诱导的菊花成花过程.     

Cr3+和Cd2+对普通小球藻生长及抗氧化酶活性的影响

[目的] 为探究重金属对淡水绿藻生长的影响。[方法] 选取对水质检测具有明显指示作用的普通小球藻（Chlorella vulgaris）为实验材料,CdCl₂·2H₂O和CrCl₃·7H₂O提供重金属离子,探究不同浓度Cr³⁺和Cd²⁺在单一和复合胁迫下对藻细胞浓度、叶绿素a及相关抗氧化酶活性的影响。[结果] 随着Cr³⁺和Cd²⁺浓度不断增加,藻细胞浓度呈先增长后下降趋势;叶绿素a含量呈现先下降后升高再下降的现象,浓度为1 mg/L的单一和复合胁迫下有最大值,且毒性作用表现为Cr³⁺ < Cd²⁺ < Cr³⁺+Cd²⁺;与藻细胞膜相关的丙二醛（MDA）和过氧化氢（H₂O₂）含量随着重金属离子浓度的增大而增长;重金属离子浓度低于10 mg/L时对藻细胞内抗氧化酶系统中的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）表现为促进作用,而大于10 mg/L时具有抑制作用。[结论] 结果表明在单一或复合重金属胁迫下,普通小球藻会充分调动与抗逆性相关的酶来维持自身的正常生长。     

Calcium snapshots in the stigma and style of medlar (Lycium barbarum L.) during pollen germination and pollen tube growth suggest active calcium oscilations

Abstract

The stigma (tip of the pistil) of medlar is wet and covered with stigmatic exudate at anthesis. The exudate contains many vesicles with abundant calcium precipitates. After deposition on the stigma, the pollen grain undergoes hydration, displaying signs of calcium ion (Ca²⁺) transfer from the exudate vesicles into the pollen grains. Calcium precipitates in the pollen cytoplasm are concentrated into small vacuoles that fuse to form large vacuoles, which provide turgor pressure to push the cytoplasm to the apical region of the growing pollen tube. Many calcium precipitates are present in the stylar transmitting tract, which displays a calcium gradient: fewer precipitates are localised in the distal (upper) transmitting tissue below the stigma, and more precipitates are present in the transmitting tract at the style base. The emporal and spatial distribution of calcium in the stigma and style of medlar suggests that it satisfies the demand for calcium in vivo and played some functional significance.     

两种云杉种子萌发和幼苗生长对环境因子的适应性

青海云杉是我国沙区通过种子育苗引种成功的物种。通过对不同储藏时间青海云杉和沙地云杉种子生活力测定、种子萌发对温度、光照、水盐胁迫以及幼苗生长对水盐胁迫和沙埋的响应实验,比较两种种子萌发和幼苗生长对环境因子适应性,为沙地云杉在我国沙区广泛引种提供参考。结果表明:1)在2年的储藏过程中,沙地云杉和青海云杉种子生活力分别由79%和72%下降了19%和5%; 2)沙地云杉和青海云杉种子适宜萌发温度分别为15—30℃和10—30℃,最适萌发温度分别为25℃(72%)和25/15℃(69%),除10℃和10/30℃外,两种种子萌发率在各温度下没有显著差异; 3)沙地云杉种子萌发光照条件为14 h光照/8 h黑暗交替(67%),青海云杉为24 h光照(61%)或24 h黑暗(61%); 4)水势在-2.7—0 MPa时,2种云杉的IGR(初始萌发率)、RGR(恢复萌发率)、ISL(初始幼苗长度)和RSL(恢复幼苗长度)均没有显著差异; 5) NaCl浓度在200 mmol/L和250 mmol/L,青海云杉种子IGR显著大于沙地云杉,NaCl浓度在0—450 mmol/L,青海云杉和沙地云杉种子RGR没有显著差异,当NaCl浓度为50 mmol/L和100 mmol/L,青海云杉ISL显著大于沙地云杉; 6)在0.5—2.0 cm沙埋深度时,青海云杉出苗率显著高于沙地云杉,沙地云杉最适沙埋深度0.5 cm,青海云杉为0.5—1.5 cm。因此,青海云杉种子萌发和幼苗生长比沙地云杉有更强的环境适应性,但只要采取合理的播种时间、播种深度和水分管理等措施,沙地云杉会和青海云杉一样在我国沙区大面积引种育苗。     

Hemispheric asymmetry of rapid chloride responses to inositol trisphosphate and calcium in Xenopus oocytes

Shallow injection of inositol 1,4,5-trisphosphate (IP₃) near the animal pole of the Xenopus oocyte resulted in a large depolarizing current that decayed rapidly. A similar injection near the vegetal pole produced a much smaller response characterized by a significantly slower rate of decay. Injection of CaCl₂ near the animal pole of the oocyte resulted in a large depolarizing current characterized by rapid rise and decay times. Injection near the vegetal pole of the cell produced responses that exhibited similar amplitudes but much longer rise and decay times. The protein kinase C (PK-C) activator, β-phorbol 12-myristate 13-acetate (PMA), significantly enhanced the rapid responses to IP₃ injections at either hemisphere but did not affect the amplitudes of the responses to CaCl₂. The PK-C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) had no effect on the responses to CaCl₂. These results imply an asymmetric distribution of calcium stores and chloride channels between the two hemispheres of the oocyte.     

大豆斑疹病菌铁摄取因子PiuB在致病性中的作用分析

铁作为生命必需的基本元素,在细菌生长代谢过程中具有重要作用。然而,大豆斑疹病菌(Xanthomonas axonopodis pv. glycines, Xag)中编码铁摄取因子的piuB基因是否参与病原菌的铁摄取和致病性并不清楚。为解析PiuB的作用,采用同源重组策略获得了Xag的piuB基因缺失突变株(ΔpiuB),并对该突变株进行功能研究。研究表明：相较于野生型,突变株ΔpiuB在寄主大豆上的毒性和生长能力显著削弱;铁载体分泌量激增;对Fe³⁺、Cu²⁺、Zn²⁺和Mn²⁺的敏感性显著增强。此外,该突变株的H₂O₂抗性、胞外多糖产量、生物膜形成能力以及游动性等相较于野生型均显著减弱;添加外源Fe³⁺不能有效恢复ΔpiuB的上述特性;功能互补株可完全恢复ΔpiuB的缺陷性表型至野生型水平。这说明PiuB是Xag摄取Fe³⁺的潜在因子,并且是Xag在寄主大豆上致病所需的。     

肌球蛋白轻链激酶非激酶活性调节磷酸化肌球蛋白ATP酶活性及肌丝运动

肌球蛋白轻链激酶(myosin light chain kinase,MLCK)具有激酶和非激酶活性,在平滑肌收缩过程中起着关键酶调控的作用.为进一步阐明MLCK非激酶活性在平滑肌收缩过程中的调节作用,利用已删除部分激酶区域的MLCK重组体(pGEXF6.5)在大肠杆菌中进行表达,采用亲和层析技术纯化表达的MLCK片段,应用EnzChek磷分析试剂盒检测MLCK片段对磷酸化肌球蛋白、水解重酶解肌球蛋白(heavymeromyosin,HMM)及肌球蛋白亚片段1(subfragmentl,S1)ATP酶活性的影响,体外检测MLCK片段对肌动蛋白肌丝运动的调节.研究结果显示,pGEX-F6.5重组表达载体在大肠杆菌中以可溶性GST融合蛋白的形式表达.该融合蛋白经Glutathione-Sepharose4B纯化、SDS-PAGE鉴定得到较纯的单一表达条带.纯化的MLCK片段对磷酸化肌球蛋白、HMM和S1的ATP酶活性均有明显激活作用.MLCK片段激活磷酸化肌球蛋白ATP酶活性为:Vmax=(19.426±1.669)倍;Km=(0.486±0.106)μmol/L,MLCK片段对磷酸化HMM和S1的ATP酶活性也有相似的刺激作用.体外肌丝运动研究表明,随着MLCK片段浓度的增加,磷酸化肌球蛋白与肌动蛋白结合的数量不断增加,肌丝运动的速度也随之增加.上述结果表明,MLCK的C端非激酶活性具有调节磷酸化的肌球蛋白ATP酶活性及肌丝运动的作用.     

外源Ca2+和IBA对NaCl胁迫下能源植物杂交狼尾草幼苗生长的影响

以能源植物杂交狼尾草(Pennisetum americanum×P.purpureum)为实验材料,在NaCl胁迫条件下用外源IBA(100 mg/L),CaCl_2(浓度分别为0、1、2、5 mmol/L)处理杂交狼尾草幼苗,处理3周后测定植物的存活率、鲜重、干重、株高、生根数和地上部分、地下部分的离子含量。结果表明,经过IBA溶液预处理的杂交狼尾草幼苗的存活率、鲜重、干重、株高、生根数明显高于未处理的幼苗;在NaCl胁迫下,随着外源Ca~(2+)浓度的升高,杂交狼尾草幼苗的存活率、鲜重、干重、株高、生根数以及Ca~(2+)含量都明显升高并在CaCl_2浓度为2 mmol/L时达到最大值;随着外源Ca~(2+)浓度的升高,Na~+含量、Na~+/K~+降低,当CaCl_2的浓度为2mmol/L时,Na~+含量、Na~+/K~+最低。以上结果表明外源Ca~(2+)和IBA对NaCl胁迫下杂交狼尾草幼苗生长有促进作用,可以缓解NaCl胁迫对杂交狼尾草幼苗生长的抑制作用,提高杂交狼尾草幼苗在NaCl胁迫下的成活率;缓解盐害的最适的Ca~(2+)浓度为2mmol/L。     

重金属Cr6+胁迫对茳芏生理生态特征的影响

采用盆栽模拟试验,研究了不同水平重金属Cr6+对茳芏生理生态的影响,探索了茳芏对重金属的抗性机理,充实有关盐沼植物的污染生态学研究。结果表明:(1)Cr6+胁迫对茳芏生物量具抑制作用;(2)叶绿素含量及叶绿素a/b比值显著降低,并对净光合速率(Pn)、胞间CO2浓度(Ci)、蒸腾速率(Tr)及气孔导度(Gs)产生显著负面影响;(3)各浓度Cr6+胁迫对茳芏根系活力表现为抑制效应;(4)在Cr6+胁迫下,茳芏过氧化氢酶(CAT)活性均比对照低(除50mg/L外),超氧化歧化酶(SOD)活性随Cr6+浓度增加呈降低趋势,而过氧化物酶(POD)活性则持续上升。丙二醛(MDA)、细胞膜透性和脯氨酸(Pro)随Cr6+浓度增加显著增加,表明Cr6+胁迫对茳芏细胞质膜系统及主要细胞器的结构与功能都具有较强的破坏作用。