气候因子对东北羊草草原羊草群落产量影响的分析

根据羊草［Ａｎｅｕｒｏｌｅｐｉｄｉｕｍ ｃｈｉｎｅｎｓｅ （Ｔｒｉｎ．） Ｋｅｎｇ］群落地上部产量的１３ 年定位观测资料,应用关联分析方法对羊草群落产量与主要气候因子动态的相互关系进行了探讨。分析结果表明,Σ７—８ 月降雨量、Σ６—８ 月降雨量／Σ６—８ 月温度和Σ４—７ 月日照对羊草群落产量的关联度,分别为０．４７、０．４１ 和０．３５。水分是羊草群落产量的主要限制因子,其次是水热因子的配合。并应用多元回归模型和周期方差分析方法的结合,对羊草群落产量进行了模拟,模拟率达９０％ 以上     

■木新芽变离体培养体系研究

为保存和加快繁殖(?)木新芽变材料,采用离体培养技术对外植体进行了愈伤组织诱导,分化,丛芽增殖和生根培养的研究．结果表明：叶片形成的愈伤组织都不分化,而茎段愈伤组织在含细胞分裂素 BA,KT 的培养基中均可分化,以 MS+KT0．6+IBA0．5培养基分化效果好,分化率达3．0个芽/块．1/2MS+IBA 2 mg/L 培养基最适合生根培养;芽变材料在黑暗条件下生根率达100%．     

碱胁迫对羊草和向日葵的影响

以抗盐碱性较强的单子叶植物羊草和双子叶植物向日葵为材料,对其进行中性盐、碱性盐和各种中碱性混合盐等胁迫处理,以日相对生长率(RGR)为主要胁变指标分析各种胁迫的特点及其相互关系.结果表明,碱性盐胁迫与中性盐胁迫实际上是既相关又有本质区别的两种不同胁迫,应该将碱性盐胁迫定义为碱胁迫,而将中性盐胁迫定义为盐胁迫.碱胁迫区别于盐胁迫的关键是高pH值.以缓冲量作为碱胁迫的胁强指标,而以盐度作为盐胁迫的胁强指标较为理想.盐碱混合胁迫时,两种胁迫表现出协同效应.     

中药薤白的研究进展

从生药来源、化学成分、药理活性及临床应用等几个方面对中药薤白的研究进展进行了综述,为该药的进一步研究及开发提供了参考。     

松嫩平原羊草草原凋落物层群落学作用的研究

 植物的萌发数量与凋落物量呈抛物线型,峰值出现在200g·m-2处,凋落物对植物萌发影响主要是通过影响地表温度和土壤水分而起作用。群落的物种数随着凋落物量增加而增加,峰值出现在800g·m-2处,种饱和度达14种·m-2,峰值后略有下降。群落优势种羊草(Aneurolepidium chinense)的密度、平均高度、盖度和地上生物量随凋落物量的变化趋势基本相同,峰值出现在600g·m-2左右。凋落物层对群落的演替动态有一定的影响,凋落物量相近的样地差异较小,随着凋落物量的增加,群落间差异越来越大。群落地上和地下生物量随凋落物量的变化呈单峰曲线,地上生物量峰值出现在600g·m-2处,地下生物量出现在700g·m-2处,地下生物量/地上生物量值随凋落物量变化呈V字型,最小值出现在550g·m-2左右。     

过表达谷胱甘肽合成酶基因增强烟草对镉的耐受性

随着工业的发展,土壤污染问题愈发严重,利用基因工程修复土壤技术备受青睐,因此,开发重金属应答中的限速酶基因,将为植物修复重金属污染的土壤提供可应用的基因资源.通过RT-PCR及末端克隆方法获得枸杞谷胱甘肽合成酶 (Lycium chinense,Glutathione synthetase,LcGS>) 基因,采用半定量RT-PCR分析了枸杞LcGS在不同时间镉(Cd)胁迫下表达量的变化,LcGS表达量随着胁迫时间的延长而增强,胁迫9h、12h和24h 后LcGS表达量维持在较高水平.同时构建了植物双元表达载体pCAMBIA2300-LcGS,通过农杆菌介导的方法将LcGS基因转入烟草,PCR证明了LcGS基因成功整合到烟草基因组中,在Cd处理条件下,转基因植株谷胱甘肽 (glutathione,GSH)、植物螯合肽(phytochelatins,PCs)和叶绿素含量比对照组明显高,即转基因植株对重金属的耐逆性比对照组更强,因此,过表达GS植物将是植物修复重金属污染的一个有效策略.     

北京东灵山地区不同海拔柴胡居群的遗传多样性

利用ISSR技术对北京东灵山地区不同海拔的6个柴胡居群进行分析,观察不同海拔柴胡居群的遗传多样性。结果表明,东灵山地区不同海拔柴胡居群的遗传多样性差异较大,海拔1135m居群表现出较高的遗传变异水平,高海拔居群遗传多样性较低;遗传距离与海拔差距有一定的相关性,相邻海拔的不同柴胡居群间具有相对较低的遗传距离;柴胡具有较强的遗传分化趋势,且大部分变异存在于居群内。不同海拔导致的异质生境及基因流是影响柴胡居群遗传多样性的主要原因。     

紫茎泽兰微生物发酵生产木糖醇的工艺

木糖醇（ｘｙｌｉｔｏｌ）是一种天然五碳多元醇,存在于许多水果、蔬菜及蘑菇中,但含量均很低,其中以蘑菇（ＡｇａｒｉｃｕｓｃａｍｐｅｓｔｒｉｓＬ．ｅｘＦｒ．）含量较高,约为１００ｍｇ／ｋｇ（干重）;木糖醇也是一种常见的代谢中间体,存在于哺乳动物的碳水化合...     

Genetic variation of geminiviruses: comparison between sexual and asexual host plant populations

One of the most promising hypotheses for the evolution of sex is that sexual reproduction is advantageous because it increases the rate of adaptive evolution in response to parasites. To investigate this advantage of sex, we compared genetic variation of geminiviruses infecting sexual and asexual populations of Eupatorium (Asteraceae). The infection frequency was 37.5% in the sexual population and 87.8% in the asexual population. The lower infection frequency in the sexual population might be the result of higher genetic diversity of host plants. If geminiviruses have diverged to counter defence systems of genetically variable hosts, genetic diversity of viruses is expected to be higher in sexual host populations than in asexual host populations. To test this expectation, we used single-strand conformation polymorphism (SSCP) analysis to examine genetic diversity of the geminiviruses in a DNA region containing the open-reading frame (ORF) C4 gene, which is known to function as a host range determinant. As predicted, higher genetic diversity of viruses was observed in the sexual population: three SSCP types were found in the asexual population while six types were found in the sexual population. Sequencing of the polymerase chain reaction (PCR) products revealed further genetic diversity. Phylogenetic analysis of the sequences showed that the SSCP types belonged to four different clades. Several SSCP types from the same clade were found in the sexual population, whereas the asexual population included only one SSCP type from each clade. Amino acid replacements of ORF C4 are suggested to be accelerated in the sexual population. This evidence supports the hypothesis that sexual reproduction is advantageous as a defence against epidemic disease.     

Application of multidimensional gas chromatography to the enantioselective characterisation of the essential oil of Eupatorium buniifolium Hooker et Arnott

The qualitative and quantitative composition of the essential oil from aerial parts of Eupatorium buniifolium Hooker et Arnott (Asteraceae) has been investigated for the first time. The essential oils were obtained by steam distillation of leaves and analysed by GC-MS; 44 components were identified. Monoterpene and sesquiterpene hydrocarbons, especially alpha-pinene (14.7%), beta-elemene (12.2%), germacrene D (11.5%), trans-beta-guaiene (6.5%) and (E)-caryophyllene (4.3%), were the major constituents found in the oils. The characterisation of E. buniifolium by enantioselective GC was performed by evaluation of the enantiomeric ratios of alpha-pinene, sabinene, beta-pinene, limonene, terpinen-4-ol and germacrene D.