贵州小檗属植物(小檗科)叶脉序研究

采用制作叶脉标本和透明叶标本的方法,对贵州产28种2变种小檗属植物叶脉特征进行比较研究。结果表明:贵州小檗属植物的脉序类型有5种:半达缘羽状脉、花环状半达缘羽状脉、简单弓形羽状脉、花环状弓形羽状脉和混合型。叶脉分支一般有五级:1一级脉构架均为羽状脉,粗度有很粗、粗、中等粗细和纤细四种类型,分支方式包括单轴分支和合轴分支;2粗二级脉构架中有分支达缘或分支均不达缘,与中脉夹角变化各异,内二级脉存在或缺失,细二级脉半达缘、真曲行或简单弓形,间二级脉类型复杂多变但频度种间有差异;3三级脉贯串型、结网型或分支型;4四、五级脉网状或自由分支且常混合在一起。脉间区从发育差到良好,小脉从不分支到不均等分支等各种类型均有,叶缘末级脉缺失、不完整、钉状和环状。大部分种类叶缘具齿,每1cm齿数目和齿内腺点的特性等特征在不同种类间有区别,具有鉴定价值,但齿其它特征复杂多变或种间区别较小,同时齿内脉性状也不稳定。此外,齿的有无会对脉序类型产生影响。小檗属植物叶脉类型存在种间差异,具有重要的分类学价值,叶脉类型的变化和复杂程度显示了该属植物的进化特点;叶齿的有无和齿特征具有分类学和系统学意义。基于叶脉特征的研究结果并结合重要的外部形态学特征编制了贵州小檗属植物的分种检索表。研究结果可为小檗属植物分类寻找新的依据并探讨其系统学意义。     

The alkaloid contents of sixty Nicotiana species

The alkaloid content (nicotine, nornicotine, anabasine, and anatabine) in leaves and roots of 60 Nicotiana species were analyzed by GC. All species contained alkaloids, the amounts varying with the species. There was no clearcut correlation between alkaloid amounts and subgeneric or sectional classification. The alkaloid content in the floral parts and immature and mature fruits of Nicotiana tabacum were also analyzed.     

芦芽山华北落叶松(Larix principis-rupprechtii)树轮宽度年表对气候因子的响应

在芦芽山地区采集3个不同海拔的华北落叶松(Larix principis-rupprechtii),在传统去趋势的基础上,采用"signal-free"方法对拟合曲线进行修正,避免了中等频率的气候信息引起的拟合偏差,最终建立3个不同海拔树轮宽度标准年表(STD)。同时以10a为界对上述年表进行滤波处理,得到3个低频年表。年表特征值表明,随着海拔升高,年轮平均轮宽变窄,敏感性和高频信息增强,低频信息减弱,这可能与逐渐恶劣的生境有关。中、低海拔年表的低频信息更一致,中、高海拔的高频信息更接近,而高、低海拔无论是标准年表还是高频、低频年表相似性均较差。树轮气候响应分析显示,低海拔STD年表与5月最低温负相关最为显著,STD和低频年表均与5、6月份土壤温度显著负相关,说明生境暖干,树木主要受生长季的干旱胁迫;中海拔STD年表与当年5月最高温正相关最为显著,STD和低频年表与土壤温度相关均不显著,说明生境逐渐变得冷湿,生长季的低温成为树木生长的限制因子;高海拔STD年表与气象要素相关不显著,低频年表与当年4月土壤温度正相关,说明高海拔最为冷湿,并有季节性冻土分布,生长季的土壤低温成为树木生长的限制因子。因此,全球变暖的趋势将更有利于高海拔树木的生长,而低海拔树木的干旱胁迫进一步加剧。     

A new alkaloid from south african Conium species

Recent screening of South African Conium species for alkaloids as part of taxonomic studies has yielded γ-coniceine, coniine, methylconiine, conhydrine and a new alkaloid N-methylpseudoconhydrine. The relative stereochemistry of N-methylpseudoconhydrine was ascertained by ¹H NMR decoupling experiments. This latter alkaloid was found in significant amounts in the leaf and stem of some plants investigated and was the major alkaloid along with conhydrine in the leaf and stem of one group of high altitude plants. These plants also contained significant amounts of volatile oil, the major monoterpene being myrcene.     

Quinolizidine alkaloid status of Styphnolobium and Cladrastis (Leguminosae)

Reports of quinolizidine alkaloids in Styphnolobium Schott and Cladrastis Raf. (Leguminosae) conflict with their position in recent molecular phylogenies because they are not members of a major clade of quinolizidine alkaloid-accumulating taxa. The alkaloid status of these two genera was therefore re-investigated using gas chromatography–mass spectrometry. Quinolizidine alkaloids could not be detected in extracts of leaves, flowers or seeds of S. japonicum (L.) Schott, nor in leaves of S. affine (Torrey & A. Gray) Walp., C. delavayi (Franch.) Prain, C. kentukea (Dum.-Cours.) Rudd or C. platycarpa Mak. In contrast, Calia secundiflora (Ortega) Yakovlev, also currently placed outside the major clade of quinolizidine alkaloid-producing genera in molecular phylogenies, was confirmed to accumulate a range of quinolizidine alkaloids.     

Tolerance to herbivory in lupin genotypes with different alkaloid concentration: Interspecific differences between Lupinus albus L. and L. angustifolius L.

Lupin genotypes accumulate alkaloids that act as feeding deterrents for several kinds of herbivores. Breeding sweet (low alkaloid) genotypes resulted in a greater dependence on pesticides. Besides the concentration of defensive chemicals, plants possess another way to deal with herbivory, to allocate post-damage resources to growth in order to reach compensation in biomass (tolerance).

These two ways to deal with herbivores were postulated as alternative strategies, as scarce resources allocated to one function (growth or secondary metabolism) would not be available for the other function. Genotypes could differ in the way they respond to herbivory; identifying those genotypes with greater ability to overcome the damage would be useful to decrease the use of pesticides.

The aim of this work was to compare tolerance to herbivory in Lupinus albus and Lupinus angustifolius genotypes with contrasting alkaloid concentration. Tolerance was evaluated by comparing growth and grain yield of field-grown cut and uncut plants. Cutting treatments were performed at flowering by cutting 50% of the upper shoot biomass (including the main apex, stems, flowers and leaves). Differences between species were found in their tolerance to herbivory. While L. angustifolius showed full compensation in growth or grain yield that allowed cut plants to equal controls biomass or yield after damage, simulated herbivory reduced growth and grain yield in L. albus.     

Distribution of Leguminosae tree species in different altitudinal levels along the Atlantic Rain Forest in the Brazilian coast

The Atlantic Forest is one of the most threatened tropical forests in the world. Leguminosae, by its great richness and dominance among arboreal stratum elements, is of major importance in the floristic composition and structure of this forest. We investigated the distribution of legume species on an altitudinal gradient to find out the altitudinal zones with higher richness of species; the altitudinal zones with greater floristic similarity; the possible presence of species that may be exclusive to certain vegetation types and the altitudinal amplitudes of those species, as well as the occurrence of species substitution along the altitudinal gradient. Therefore, thirty one studies conducted in different altitudinal levels between 5° S and 29° S were analyzed. A matrix with 142 tree species distributed in altitudinal zones (every 100 m) from sea level to 2100 m was built. The greatest species richness was observed in the Submontane Forest (50–500 m) with 92 species. The cluster analysis revealed a strong dissimilarity of the 1400–2100 m (Upper Montane) and 0–10 m zones (Restinga Forest). The Submontane and the Montane Forest share the highest number of species (38 ssp.). Forty species are unique to Submontane. Substitution of species was verified. Some species have their preferred habitat located at a specific altitudinal amplitude, as is the case of Inga laurina and I. subnuda (0–10 m), I. lanceifolia and Machaerium scleroxylon (800–1200 m). The Leguminosae, although well adapted to the first colonization and establishment of diverse environment, was poorly represented above 1500 m altitude.     

Respiration for maintenance and growth inReynoutria japonica ecotypes from different altitudes on Mt Fuji

Respiration for maintenance and growth ofReynoutria japonica ecotypes from altitudes of 700 and 2420 m on Mt Fuji were measured in two controlled thermal conditions. The maintenance respiration of the high-altitude ecotype at both 15 and 25°C was significantly (1.7-fold) higher than that of the low-altitude ecotype, whereas growth respiration was independent of both ecotype and temperature. The temperature coefficient (Q₁₀) of the maintenance respiration was about 1.9 in both ecotypes. The results show that there is ecotypic differentiation in the performance of maintenance respiration. It is suggested that the high maintenance respiration of the high-altitudeR. japonica ecotype is advantageous in severe upland environments but disadvantageous in a warm lowland climate in terms of carbon economy.     

Pyrrolizidine alkaloid profiles in Crotalaria species from Brazil: Chemotaxonomic significance

Gas chromatography–mass spectrometry analysis of seeds from 28 species of Crotalaria from Brazil (sections Calycinae, Crotalaria, Chrysocalycinae and Hedriocarpae) showed that pyrrolizidine alkaloids (PAs) are important as chemotaxonomic markers at the infrageneric level. The sections Calycinae and Crotalaria were characterized by 11-membered macrocyclic monocrotaline-type PAs. In the section Chrysocalycinae, a single species in the subsection Incanae, C. incana, showed integerrimine, a 12-membered macrocyclic senecionine-type, as main PA. The group close to the subsection Stipulosae (C. micans and C. maypurensis) showed distinctive PA patterns: C. micans presented mainly the 12-membered macrocyclic integerrimine, and C. maypurensis the unusual 7-hydroxy-1-methylene-8-pyrrolizidine. In the group close to the subsection Glaucae, the PAs with otonecine as the necine base were the main alkaloids, except in C. rufipila which showed an assamicadine-like PA (monocrotaline-type). The section Hedriocarpae showed main 12-membered macrocyclic senecionine-type PAs.     

Alkaloids from stem barks of Oricia renieri and Oricia gabonensis

The stem barks of Oricia renieri and O. gabonensis have yielded nine alkaloids, including furoquinolines, acridones, 3,4-pyrano-2-quinolones and a 2-amino-benzophenone. One of the pyranoquinolones isolated from O. renieri, 7-methoxy-N-methylflindersine, is reported for the first time. All alkaloids were identified on the basis of spectral data. The chemotaxonomic significance of the alkaloids of these two species is discussed.     

Tolerances of wild potato species from different altitudes to cold and heat

The ability of wild potatoes (Solanum spp.) to adapt to potentially stressful environmental temperatures was investigated by measuring the cold and heat tolerances of plants grown near sea-level in Lima following collection of tubers from plants growing naturally at altitudes ranging from 450 to 4,200 m. Relative cold tolerance was measured in leaves stored at 0°C by the decrease in the induced rise of chlorophyll fluorescence. Similarly, changes in chlorophyll fluorescence were used to determine the relative heat tolerance of leaves heated at 41°C for 10 min. With increasing altitude, the cold tolerance of different species tended to increase and conversely, heat tolerance decreased. However, these two genotypic adaptations were not closely correlated and appear to vary independently of each other in response to climate.     

Antioxidant composition of selected high alpine plant species from different altitudes

Selected high alpine plant species were collected from different elevations in the Obergurgl/Ötztal subnival and nival regions in Austria to investigate the content of antioxidants in plants growing under the particular in vivo conditions experienced in this area (e.g. chilling stress, short vegetation period and high irradiation). The contents of antioxidants (ascorbic acid, tocopherol and glutathionc) and photosynthetic pigments were measured throughout the day. The contents of most compounds were found to follow a diurnal rhythm, with the maximum occurring at midday and the minimum during the night. It was not clear whether these fluctuations were temperature-dependent or light-dependent. Analyses of the antioxidant spectrum in the same plant species at different altitudes (and thus under different environmental conditions: as altitude increases, for example, day temperature decreases and light intensity increases) revealed that the total amount of antioxidants increases as altitude increases. This enhancement was mainly due to ascorbic acid contents. Each plant species displayed a specific reaction to the increase in stress that accompanies an increase in altitude, resulting in a broad adaptation spectrum for these plants. The present study suggests that the combined effect of lower temperature and higher light intensity induces higher antioxidant contents.     

Influence of dietary alkaloids on survival and growth of Spodoptera littoralis

A total of 25 alkaloids including benzylisoquinoline, monoterpenoid indole, quinolizidine, tobacco and tropane alkaloids were studied for deleterious effects towards neonate larvae of the generalist herbivore Spodoptera littoralis. Alkaloids were incorporated into artificial diet at several concentrations including the respective natural concentration as present in planta as well as two arbitrarily chosen concentrations (0.1 and 0.2% g⁻¹ fresh wt.) for comparison of the bioactivities. After 5 days of exposure almost all of the alkaloids studied reduced larval growth compared to controls. Larval survival, however, was reduced by more than 50% compared to controls only in the presence of berberine, colchicine and nicotine. Several compounds including for example the Cinchona alkaloids quinidine, quinine or cinchonidine which showed little effect on larval survival after 5 days of exposure turned out to be considerably more active when insects were exposed to the respective alkaloids for their whole larval period. In the chronic exposure studies all of the latter alkaloids caused high larval mortality. The pupal weights were significantly lower than those of the controls. Dietary utilization studies indicated that feeding deterrency is important for the adverse effects caused for example by berberine, quinine or quinidine whereas the high larval mortality observed in the presence of cholchicine or nicotine seems to be primarily due to the acute toxicity of these latter alkaloids.     

青檀果内生真菌菌群的组成及多样性

为进一步了解我国古老特有的野生植物青檀内生真菌的组成特征,以安徽琅琊山自然保护区内的野生青檀果为研究对象,采用组织分离和形态学鉴定的方法对青檀果内生真菌进行了分离和鉴定.结果表明: 从500个组织块中共分离内生真菌428株,隶属于3目4科20属,未产孢的菌株暂归为无孢菌群(80株,18.7%).暗梗孢科和球壳孢科是青檀果内生真菌的优势科,分别占38.1%和32.9%,交链孢属和拟茎点霉属为其优势属,分别占27.1%和16.8%.青檀果不同部位内生真菌的组成存在差异,以种子中分离的内生真菌数量最多(19属181株,占42.3%),果翅中分离的内生真菌最少(7属88株,占20.6%).除了交链孢属为3个不同部位的共同优势属之外,拟茎点霉属和大茎点霉属分别是果柄和果翅的优势属.果柄和果翅内生真菌菌群的组成相似性最高(C_S=0.78),种子和果翅的相似性系数最低(C_S=0.50).分析显示,果柄与果翅在内生真菌菌群组成上无显著差异,而种子与果柄、种子与果翅在内生真菌菌群组成上均存在显著差异.     

太白山栎属树种气孔特征沿海拔梯度的变化规律

气孔是植物与外界环境进行水分和气体交换的主要通道,调节植物碳同化和水分散失的平衡关系,在一定程度上反映植物对外界环境变化的适应。沿太白山北坡1100—2300 m海拔,测定4种栎属树种的气孔性状,分析气孔性状沿海拔的变化规律和其对环境因子的响应。结果表明:(1)气孔密度与气孔长度间的负相关在4个树种间均显著存在(P0.05);除栓皮栎(Quercus variabilis)外,气孔密度与潜在气孔导度指数的正相关关系均达显著水平;而气孔宽度与气孔长度之间只在栓皮栎和锐齿栎(Q. aliena var. acuteserrata)达到显著水平。(2)栓皮栎和槲栎(Q. aliena)的气孔长度和宽度随海拔升高而下降,气孔密度、潜在气孔导度指数增加,辽东栎(Q. wutaishansea)变化形式则相反;锐齿栎气孔宽度减小,其余性状沿海拔呈单峰变化,在约1600 m处气孔长度达到最小值,气孔密度和潜在气孔导度指数达到最大值。(3)与土壤因子相比,气孔性状主要受气候因素的影响。潜在气孔导度指数与大气温度、空气湿度成极显著正相关(P0.01),与降水量显著负相关(P0.05)。其中,空气相对湿度是影响潜在气孔导度指数的主要因素,能够解释气孔变异的22.9%。本研究结果对于深入认识秦岭太白山地区栎属树种对环境变化的响应和适应提供理论证据。