共查询到20条相似文献,搜索用时 8 毫秒
1.
Low growing, compact cushion plants are a common and often dominant life form in temperate and subpolar alpine habitats. The
cushion life-form can modify wind patterns, temperature and water availability and thus cushion species could be expected
to act as nurse-plants facilitating the establishment of other alpine plant species on their surfaces. It has been suggested
that the nurse effect should be most pronounced under more stressful environmental conditions, as found with increasing elevation
in the alpine. One of the approaches used to detect the nurses has been the study of spatial associations among species, in
which extreme clumping within or beneath one species has been interpreted as evidence of nursing. We characterized microclimatic
conditions (soil and air temperature) within and outside cushions of Azorella monantha at two elevations (700 m a.s.l., corresponding to an elevation just above treeline, and 900 m a.s.l., corresponding to the
upper limit of the cushion belt zone) on Cerro Diente in the Patagonian alpine of southern South America (50° S) and recorded
all plant species growing upon cushions of various sizes and for paired sampling areas of equivalent sizes outside cushions.
At 5 cm depth, soil temperature was slightly higher under cushions than under bare ground, but only significantly so at 900
m. Air temperature at ground level was significantly higher in the cushion microhabitat at both 700 m and 900 m, with the
difference being more exaggerated at the highest elevation. At 700 m, a total of 27 species were recorded growing within cushions
as compared to 29 outside cushions. At 900 m the corresponding numbers were 34 and 18. At the highest elevation, significantly
more species grow within cushions than for equal areas outside cushions. Here moreover, 17 (48.6%) species grew preferentially
within cushions, with eight of the latter being limited to the cushion microhabitat at this elevation. However, at 700 m there
was no significant difference in species richness in the two microhabitats, and only one species (3.1%) grew preferentially
on cushions. Considering individual species, nine occurring at both elevations showed non-preferential recruitment on cushions
at 700 m, but significantly higher frequencies on cushions at 900 m. Results suggest striking altitudinal variation in the
association with Azorella monantha on Cerro Diente, ranging from a very strong at 900 m to near absence at 700 m. Milder air and soil temperatures, shelter
from wind, and greater water availability within cushions as opposed to outside cushions are discussed as possible factors
favoring strong plant recruitment on cushions at higher elevations in the harsh Patagonian alpine environment.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
3.
Several plants invade the cushions of Laretia acaulis in the high Andean communities of central Chile. Humus develops among the rosettes, and 42 different species settle on the cushions. Most of these species are also found outside the cushions. Semi-woody chamaephytes, hemicryptophytes and cryptophytes have a similar cover on both substrates, while the cover of woody chamaephytes and therophytes is smaller on the cushions. The diversity and cover of invading plants, which vary with altitude, result from interactions among the environmental conditions, cushion morphology and the surrounding vegetation.This study is part of the Chilean contribution to the Man and the Biosphere (MAB) Programme, within the framework of the UNEP/UNESCO Andean Project (1105-77-01).Nomenclature is given in the Appendix.We thank M. T. K. Arroyo, C. Marticorena and O. Matthei, and the Herbaria of the Universidad Concepción and the Museo de Historia Natural, for help with identification of species. 相似文献
4.
蒲公英糖蛋白体内外抗氧化作用研究 总被引:2,自引:0,他引:2
为了探讨蒲公英糖蛋白(TMGP)体内外抗氧化活性,采用H2O2、Fe2+、DPPH.和总抗氧化能力反应体系,检测蒲公英糖蛋白体外抗氧化活性,并与VC进行比较;同时建立D-半乳糖所致衰老小鼠模型,测定并比较TMGP组与模型组的血清、肝脏和脑内MDA含量和SOD、CAT、GSH-Px活性。结果显示:(1)随着TMGP浓度增加,其Fe2+、H2O2和DPPH.清除率均有所增加,当TMGP浓度为1.72mg/mL时,对H2O2、Fe2+清除率分别达到76.8%和55%,接近VC水平;当TMGP浓度为1.5mg/mL时,对DPPH.的清除率达到77%,也与VC水平相当,说明TMGP具有一定的体外总体抗氧化能力。(2)将TMGP按低、中、高剂量分别给小白鼠灌胃,可显著增强小鼠体内血清、肝脏、脑组织中SOD、CAT、GSH-Px活性,降低MDA含量,从而提高衰老小白鼠体内的抗氧化能力。研究表明,TMGP具有明显的体内外抗氧化作用。 相似文献
5.
An invasive dandelion unilaterally reduces the reproduction of a native congener through competition for pollination 总被引:1,自引:1,他引:1
The impact of invasive alien species on native species is of increasing global concern. Invasive plants have various negative
effects on natives through competition; however, relatively little is known about competition for pollination. The relationship
between Japanese native dandelions (Taraxacum spp.) and invasive congeners may be a typical case of such an interaction. For example, native dandelions are being replaced
by invasive congeners, especially in urban and suburban areas of Japan. To explain this phenomenon, we hypothesized that when
natives are mixed with attractive invasives, natives may suffer from reduced seed set because invasives deprive natives of
pollinators or because pollinators frequently move between species, resulting in interspecific pollen transfer. To test this
hypothesis, we studied the effect of the invasive dandelion T. officinale on the pollination and seed set of the native T. japonicum using artificial arrays of monospecific and mixed-species plots as well as natural populations. Taraxacum officinale attracted more pollinator visits, perhaps because it produced more nectar than T. japonicum. The number of pollinator visits to T. japonicum was reduced when the congeners were grown together, and pollinators moved frequently between the two species. The proportion
of seed set for T. japonicum was reduced in the presence of T. officinale in both artificial arrays and natural populations. These results support our hypothesis that interspecific competition for
pollination plays an important role in the recent replacement of native dandelions by invasive congeners in Japan. Because
invasive dandelions are apomicts, negative effects are incurred only by sexual natives. Thus, this system can be recognized
as a rare case of interspecific interaction through pollination. 相似文献
6.
铁皮石斛内生真菌次生代谢产物研究 总被引:1,自引:0,他引:1
为了解铁皮石斛(Dendrobium officinale)内生真菌Phyllosticta aristolochiicola的次生代谢产物,从该真菌中分离得到15个化合物,经波谱分析分别鉴定为N-methyl-2-pyrolidinone (1)、环-(甘氨酸-L-脯氨酸)(2)、环-(D-丙氨酸-L-脯氨酸)(3)、环-(L-缬氨酸-L-脯氨酸)(4)、环-(L-亮氨酸-L-脯氨酸)(5)、cyclo-(L-Leu-D-4-hydroxyprolinyl)(6)、环-(L-苯丙氨酸-L-脯氨酸)(7)、环-(L-苯丙氨酸-L-4-羟基脯氨酸)(8)、环-(L-酪氨酸-L-脯氨酸)(9)、环-(L-苯丙氨酸-L-亮氨酸)(10)、啤酒甾醇(11)、对羟基苯乙醇(12)、对羟基苯乙酸(13)、(2S,3R)-1-(4-羟基苯基)丁烷-2,3-二醇(14)和(2R,3S)-1-苯基丁烷-2,3-二醇(15)。采用MTS法检测抗肿瘤活性表明,化合物2、10和14对HL-60、A-549、SMMC-7721、MCF-7和SW-480细胞株具有一定的抑制活性。 相似文献
7.
铁皮石斛内生真菌研究进展 总被引:1,自引:0,他引:1
目前已经从不同生境的铁皮石斛(Dendrobium officinale Kimura et Migo)中分离到内生真菌252株,这些内生真菌涵盖了真菌门(Eumycota;Mycobionta)5个亚门中的半知菌亚门(Deuterornycotina)、担子菌亚门(Basidiomycotina)和子囊菌亚门(Ascomycotina)等3个亚门,已经鉴定的内生真菌分属于48个属。有些内生真菌对铁皮石斛的种子萌发和植株生长均有促进作用。对铁皮石斛内生真菌的多样性和分类、铁皮石斛内生菌与宿主的关系进行了综述,探讨研究中存在的问题, 并对今后研究方向提出建议。 相似文献
8.
Flavonoids and coumaric acid derivatives were identified from dandelion flower (Taraxacum officinale). Characteristics of chain-breaking antioxidants, such as extended lag phase and reduced propagation rate, were observed in oxidation of linoleic acid emulsion with the addition of dandelion flower extract (DFE). DFE suppressed both superoxide and hydroxyl radical, while the latter was further distinguished by both site-specific and non-specific hydroxyl radical inhibition. DPPH-radical-scavenging activity and a synergistic effect with alpha-tocopherol were attributed to the reducing activity derived from phenolic content of DFE. A significant (p < 0.05) and concentration-dependent, reduced nitric oxide production from acterial-lipopolysaccharide-stimulated mouse macrophage RAW264.7 cells was observed with the addition of DFE. Moreover, peroxyl-radical-induced intracellular oxidation of RAW264.7 cells was inhibited significantly (p < 0.05) by the addition of DFE over a range of concentrations. These results showed that the DFE possessed marked antioxidant activity in both biological and chemical models. Furthermore, the efficacy of DFE in inhibiting both reactive oxygen species and nitric oxide were attributed to its phenolic content. 相似文献
9.
10.
为探究印度梨形孢(Piriformospora indica)对铁皮石斛(Dendrobium officinale)种子萌发和原球茎生长的影响,在铁皮石斛种子离体培养和原球茎生长阶段分别接种印度梨形孢,对其形态发育特征和生理特性进行研究.结果表明,接种印度梨形孢的铁皮石斛种子的起始萌发时间提前,接种印度梨形孢的铁皮石... 相似文献
11.
为了研究铁皮石斛的光合特性,根据Rubisco活化酶(RCA)基因的保守序列设计兼并引物,采用RT-PCR和RACE方法从铁皮石斛叶中分离到一个RCA基因,命名为DORCA(GenBank登录号KT205841)。DORCA基因cDNA全长为1 724bp,包含1 317bp开放阅读框(ORF),编码438个氨基酸。系统进化分析显示,DORCA与马蹄莲ZaRCA(AAK25801.1)亲缘关系最近。生物信息学分析表明,DORCA与其他植物的RCA蛋白具有较高一致性,属于RCA的β亚基。DORCA蛋白具有定位于叶绿体的N端转运肽,2个保守的ATP结合结构域和多个磷酸化位点。实时荧光定量PCR(qRT-PCR)分析表明,DORCA基因在茎、叶中表达;在自然光周期条件下,DORCA基因在8:30时表达量最高,20:30时表达量最低,具有明显的光诱导表达特性。 相似文献
12.
花粉管通道法介导的铁皮石斛转基因技术 总被引:1,自引:0,他引:1
该研究以含有GFP和GUS基因的质粒和农杆菌为载体,采用花粉管通道法对铁皮石斛进行转基因技术研究。结果表明:(1)铁皮石斛种子萌发和原球茎生长对卡那霉素的最低致死浓度分别为90和150 mg·L~(-1)。进一步研究证实,在筛选转化种子和原球茎时,可分别向培养基中添加100和150 mg·L~(-1)的卡那霉素进行选择培养。(2)以携带GFP和GUS基因的质粒(pSuper1300和pBI121)和农杆菌为载体,用无菌去离子水重悬质粒pSuper1300和pBI121至浓度为100 ng·μL~(-1),用2%蔗糖+1/2MS+0.1%silwet-77+0.1%AS或5%蔗糖+0.1%silwet-77+0.1 mmol·L~(-1)AS重悬携带质粒pSuper1300和pBI121的农杆菌至菌液浓度为OD_(600)=0.7~0.8;在授粉后0.5~2.5 h内使用柱头滴加法导入携带外源基因的质粒或农杆菌溶液,收集成熟的转化种子,经选择培养及PCR检测发现,几乎所有处理的转化材料均能检测出外源GFP和GUS基因片段。另外,与农杆菌相比,以质粒为载体进行转化,可获得更高的结实率。该研究结果为铁皮石斛的基因工程育种提供了参考。 相似文献
13.
为了阐明兰科菌根真菌对铁皮石斛光合作用的影响及机制,采用盆栽方式研究了兰科菌根真菌对铁皮石斛幼苗生长的影响,并分析了叶片中叶绿素含量、光合参数、叶绿素荧光参数以及pepc基因表达的变化。结果表明:(1)兰科菌根真菌促进了铁皮石斛幼苗生长,接种兰科菌根真菌的铁皮石斛的株高、根重、茎叶重和总生物量分别是未接种对照组的1.21、1.54、1.71和1.68倍;而且可显著提高叶片中叶绿素含量、叶片净光合速率(Pn)、蒸腾速率(Gs)和气孔导度(Tr)。(2)接种兰科菌根真菌的铁皮石斛叶片潜在光化学效率(Fv/F0)、最大光化学效率(Fv/Fm)、光化学猝灭系数(qP)、非光化学猝灭系数(qN)、实际光化学反应量子效率(Yield)和表观光合电子传递速率(ETR)均高于未接种对照组。(3)菌根真菌能促进pepc基因的表达,增强PEPC活性,提高铁皮石斛叶片的光合碳同化能力。研究表明,菌根的形成可以提高铁皮石斛叶片光合性能和pepc基因的表达水平,促进铁皮石斛幼苗的生长。 相似文献
14.
为筛选出促进铁皮石斛(Dendrobium officinale)生长的差异表达基因和差异代谢物,对瘤菌根菌与无菌盆栽铁皮石斛苗共生后形成的侧根根系进行转录组、代谢组和双组学联合分析。结果表明,转录组分析共找到262条差异表达基因富集到了35条通路中,其中内质网蛋白质加工通路途径的差异基因最多,其次为氨基糖和核苷酸糖代谢通路。代谢组分析共检测出194个差异代谢物富集到33个KEGG通路中,其中代谢途径的差异代谢物最多有133个,其次为不同环境的微生物代谢途径的差异代谢物有70个。通过联合分析,有9个差异基因的差异表达导致丝氨酸、谷氨酸、D-甘露糖和激素等代谢物的积累量发生变化,这可能是瘤菌根菌促进铁皮石斛生长的重要原因。因此,推测瘤菌根菌促进铁皮石斛生长与氨基酸、糖、植物激素的积累及相关基因的表达变化有关。 相似文献
15.
为了解SMT2基因在铁皮石斛(Dendrobium officinale)甾醇代谢过程中的作用,利用RACE技术克隆到1个DoSMT2基因,开放阅读框为1 089 bp,编码362个氨基酸,DoSMT2相对分子量为40.345 kD,理论等电点为8.13,属于稳定的亲水性蛋白。经BLAST P检索,DoSMT2蛋白属于AdoMet-MTases超级家族,含有4个S-腺苷蛋氨酸结合位点、1个甲基转移酶保守结构域和1个甾醇甲基转移酶C末端保守结构域。系统进化分析表明,DoSMT2与深圳拟兰(Apostasia shenzhenica)的SMT2亲缘关系最近,确定其属于SMT2家族。qRT-PCR分析结果表明,DoSMT2基因在茎和叶都能表达,10月份的表达量最高,叶片的表达量显著高于茎,推断叶片的甾醇代谢比茎活跃。构建了pET-29a-DoSMT2原核表达载体,并转化大肠杆菌BL21(DE3),IPTG诱导表达出预期大小的蛋白。这为铁皮石斛DoSMT2的甲基化机制及甾醇化合物代谢研究奠定基础。 相似文献
16.
利用RT-PCR和RACE技术,从珍稀濒危药用植物铁皮石斛(Dendrobium of ficinale)中分离到一个类唾液酸转移酶(sialylt ransferase-like proteins,STLP)基因,命名为DoSTLP1(GenBank注册号KC178574).序列分析结果表明,DoSTLP1基因全长cDNA为1 340 bp,编码1条由367个氨基酸组成的肽链,分子量41.66 kD,等电点8.64;DoSTLP1蛋白具有唾液酸转移酶和糖基转移酶29家族的保守结构域(分别为1~357,87~346位氨基酸)、信号肽(1~27)和跨膜结构域(3~25,285~311).多序列比对和系统进化结果显示,DoSTLP1与多种植物的STLPs基因有较高的相似性(44.7%~53.7%),而且与水稻、玉米等单子叶植物STLPs基因的亲缘关系较近.实时定量PCR分析显示,DoSTLP1基因在铁皮石斛根、茎、叶器官中为组成型表达,其转录本在石斛根中的相对表达量较高,为叶中的2.857倍,茎和叶中的表达量无显著差异.该研究为进一步解析该基因在铁皮石斛生长发育过程中的生物学功能奠定基础. 相似文献
17.
该研究采用RACE克隆铁皮石斛钙网蛋白(calreticulin,CRT)基因DoCRT1,进行生物信息学分析,并借助定量PCR检测基因表达模式,为揭示该基因在铁皮石斛生长发育及逆境生理中的分子作用奠定基础。结果表明:(1)DoCRT1基因(GenBank登录号KT957551)cDNA全长1 672bp,ORF长1 275bp,编码一条由424个氨基酸组成的多肽,分子量49.05kD,等电点4.42,具有CRT蛋白保守的钙网蛋白/钙联接蛋白P结构域(205~320)和类伴刀豆球蛋白凝集素/葡聚糖酶结构域A(20~222)以及多个基序;蛋白N端含有一个信号肽(1~23)和一个跨膜区域(8~24),预测结果显示主要定位于细胞液泡、胞外,与多种植物CRT蛋白一致性很高(80%~87%)。(2)DoCRT1蛋白与OsCRT1/2、ZmCRT1亲缘关系近,聚在CRT进化树的CRT1/2分支。(3)qRT-PCR检测结果显示,DoCRT1基因转录本在石斛根中表达量较高,为叶中的2.23倍,且茎与叶中表达量无显著差异。 相似文献
18.
乡土植物白刺花对紫茎泽兰化感作用的响应 总被引:1,自引:0,他引:1
为了解乡土植物白刺花对紫茎泽兰化感作用的耐受程度及抵御机理,以2—3年生紫茎泽兰叶片为供体材料,用不同浓度的紫茎泽兰叶片浸提液处理白刺花种子及幼苗。结果表明:紫茎泽兰叶片浸提液对白刺花的影响为低浓度促进,高浓度抑制。当浓度为0.5%时促进效应最强,当浓度大于2.0%时抑制效应明显增加。白刺花种子萌发速率比萌发率对紫茎泽兰化感作用反应敏感,胚轴比胚根敏感,随着幼苗的生长,其抵御紫茎泽兰化感作用的能力逐渐增强,丙二醛的含量与植株生长响应规律相对应,并且经紫茎泽兰浸提液处理能极大的增加白刺花幼苗菌根率,缩短菌根形成的时间。 相似文献
19.
四种添加物对铁皮石斛原球茎生长及多糖含量的影响 总被引:2,自引:0,他引:2
为探讨铁皮石斛(Dendrobium officinale)培养基中添加物的作用,在1/2MS培养基中加入椰肉、甘蔗渣、香蕉皮和麦麸等4种添加物,研究不同浓度添加物和培养时间对原球茎生长和多糖含量的影响。结果表明,4种添加物对铁皮石斛原球茎的增殖、分化和多糖含量均有一定影响,其中添加15.0 g L–1甘蔗渣,培养60 d能明显促进铁皮石斛原球茎的增殖与分化(146.1%);而添加20.0 g L–1甘蔗渣,培养40 d能显著提高铁皮石斛原球茎多糖含量(50.4%)。这说明甘蔗渣是培养铁皮石斛原球茎的适宜添加物,既能促进铁皮石斛原球茎的生长发育,还能降低生产成本。 相似文献
20.
为了揭示铁皮石斛(Dendrobium officinale)甾醇C-24甲基转移酶2基因(DoSMT2)在甾醇代谢过程的功能,该研究通过根癌农杆菌介导法将来源于铁皮石斛的DoSMT2基因转化烟草(Nicotiana tabacum),并采用qRT-PCR技术检测DoSMT2基因在转基因烟草叶片中的表达,采用气相色谱质谱法分析菜油甾醇和谷甾醇的含量。结果显示:(1)成功获得DoSMT2基因的开放阅读框(1 119 bp),并成功构建正义植物表达载体质粒pCXSN-DoSMT2,经农杆菌介导的烟草叶盘转化法转化烟草并鉴定,获得4株阳性转基因烟草植株。(2)Southern blot结果表明,4株转基因烟草植株都有1条杂交信号带,而非转基因烟草植株没有,说明外源DoSMT2基因都以单拷贝整合到4株转基因烟草基因组中。(3)qRT-PCR检测显示,非转基因烟草未检测到外源DoSMT2基因的表达,4株转基因烟草都能检测到DoSMT2基因的表达,且表达水平差异极显著,各株系表达量高低依次为P3P1P2(P4)。(4)气相色谱质谱分析显示,转DoSMT2基因烟草叶片的菜油甾醇含量均极显著低于非转基因烟草叶片,而谷甾醇含量均极显著高于非转基因烟草叶片。研究表明,DoSMT2具有催化24-亚甲基胆甾烯醇转化形成24-亚乙基胆甾烯醇活性。 相似文献