牯岭凤仙花及其传粉昆虫在中国的潜在分布区域分析

牯岭凤仙花(Impatiens davidii)为中国特有的珍稀观赏花卉, 野生种群较小, 同时依赖特殊的传粉者三条熊蜂(Bombus trifasciatus)授粉, 为特化传粉植物, 传粉资源为限制其种群扩散的重要因素。该研究基于63条牯岭凤仙花分布数据、54条三条熊蜂分布数据、19个环境气候因子, 运用最大熵(MaxEnt)模型模拟预测当前及未来(2050s、2070s) 3种气候代表性浓度路径情景RCP2.6、RCP4.5、RCP8.5下牯岭凤仙花和三条熊蜂的潜在分布区域。结果表明: 影响牯岭凤仙花分布的主要环境因子为最暖季度降水量。当前气候条件下, 牯岭凤仙花与三条熊蜂具有较高的地理分布重合度、生态位宽度、生态位重合度, 共同分布区域占比高达99.09%, 较大程度上保证了牯岭凤仙花的传粉资源; 在未来3种气候情景下, 牯岭凤仙花分布区域向东北、华北扩张, 适生面积增加6.60-22.19万km²; 三条熊蜂适生区整体略微北移, 适生面积增加4.48-15.50万km²; 两者共同分布区域占牯岭凤仙花适生区域比例降低1.40%-9.00%, 表明未来牯岭凤仙花适生区可能受到气候变化和传粉资源缺失共同影响。     

Impacts of invasive plant species on riparian plant assemblages: interactions with elevated atmospheric carbon dioxide and nitrogen deposition

Resource competition is commonly invoked to explain negative effects of invasive plants on native plant abundance. If invasives out-compete natives, global changes that elevate resource availability may interact with invasives to exacerbate impacts on native communities. Indeed, evidence is accumulating that elevated CO₂ and N deposition decrease native biomass and simultaneously increase invasive biomass. However, superior competitive ability, and a relative increase in the magnitude of invasive impacts under elevated resource availability, remain to be definitively proven. Using model, multi-species, multi-individual riparian plant communities, where planting density was maintained by replacement of native with exotic individuals, we conducted a greenhouse, competition experiment using native (to the UK) and invaded communities exposed to ambient and elevated CO₂ (CO₂ experiment) or N availability (N experiment). We tested two hypotheses: (1) invasives are superior competitors to natives at ambient atmospheric CO₂ and N deposition; (2) negative effects of invasives on natives are exacerbated under elevated CO₂ or N availability. Our results provide some support for the first hypothesis: in the CO₂ experiment native biomass was significantly lower in invaded communities. In the N experiment, native biomass was unaffected by the presence of exotics but other characteristics (e.g. root:shoot ratios) were altered. Differences in light availability between the experiments may have modified the effects of the invasives on the native assemblages but our design did not permit us to determine this definitively. The hypothesis that elevated CO₂ and N availability benefit invasives at the expense of natives was not supported by our results. This may be explained either because the invasives showed minor responses to the resource manipulations or because native and exotic species were differentially limited by CO₂ and N. Our results confirm the expectation that invasives alter the characteristics of native assemblages but lead us to question whether elevated resource availability will magnify these effects.     

Effects of the compounds 2-methoxynaphthoquinone, 2-propoxynaphthoquinone, and 2-isopropoxynaphthoquinone on ecdysone 20-monooxygenase activity

The effects of the natural compound 2-methoxy-1,4-naphthoquinone, isolated from the leaves of Impatiens glandulifera and the synthetic compounds 2-propoxy-1,4-naphthoquinone and 2-isopropoxy-1,4-naphthoquinone on ecdysone 20-monooxygenase (E-20-M) activity were examined in three insect species. Homogenates of wandering stage third instar larvae of Drosophila melanogaster, or abdomens from adult female Aedes aegypti, or fat body or midgut from fifth instar larvae of Manduca sexta were incubated with radiolabelled ecdysone and increasing concentrations (from 1 x 10(-8) to 1 x 10(-3) M) of the three compounds. All three compounds were found to inhibit in a dose-dependent fashion the E-20-M activity in the three insect species. The concentration of these compounds required to elicit a 50% inhibition of this steroid hydroxylase activity in the three insect species examined ranged from approximately 3 x 10(-5) to 7 x 10(-4) M.     

Pollen Morphology of Impatiens L. (Balsaminaceae) and Its Taxonomic Implications

Two forms of pollen morphology of Impatiens L. (Balsminaceae) have been described before: 3-colpate and 4-colpate pollen grains. Pollen grains of 13 species of Impatiens on Mt. Omei were examined under SEM for the first time and both forms were observed here, which imply the diversity of species in this region. Of the two forms, 3-colpate one is quite similar to that of the genus Hydrocera Blume (Balsaminaceae) in external morphology. This relation also exists between the 3-colpate pollen group and Hydrocera in habit, habitat, and distribution, etc. It is supposed that the group with 3-colpate pollen type is a natural one, and may have a close relationship with Hydrocera. The pollen morphology is of important significance in classification of the taxa and evaluation of systematic position in the fami-ly balsaminaceae.     

Seed Morphology of Impatiens L. (Balsaminaceae) and Its Taxonomic Significance

The seed surface of 12 species of Impatiens L. from Mt. Omei was observed under SEM for the first time. The important characters used in the paper include cell specialization on seed surface, arrangement pattern of the cells, the degree of the cell elevation, chalazal zone morphology and appendix at the tail of the seed. According to these characters, the seed surface morphology of 12 species can be divided into two types: 1. the seed without conspicuous differentiation of surface cells, laevigate on the surface, represented by I. wilsoni; the seeds of species indicated by 3-colpate pollen grains are expected to belong to the type. 2. the seed with the large cell elevation at different levels, surface scabrous, represented by the other 11 species; most species with 4-colpate pollen have this kind of seeds. The results verify that the seed morphology of the genus can supply characters significant to taxonomy of the genus at species level. The evolution of seed surface of Impatiens has close correlation with that ofthe flower and pollen morphology.     

Impatiens macrovexilla var. yaoshanensis S. X. Yu,Y. L. Chen & H. N. Qin,a new variety of Balsaminaceae from Guangxi,China

Impatiens macrovexilla Y. L. Chen var. yaoshanensis S. X. Yu, Y. L. Chen & H. N. Qin, a new variety of Balsaminaceae from Guangxi, China, is described. Variety yaoshanensis differs from the typical variety by having ovate-orbicular or ovate-oblong leaves, entire lateral sepals, an obvious auricle and entire distal lobe of the alae and visibly ridged seeds. Micromorphological characters of the pollen grains and seed surface under SEM of the two varieties also support the recognition of this taxon.     

不同密度下凤仙花重要形态性状与花朵数的关系

对30cm×30cm和50cm×50cm种植密度下的凤仙花(Impatiens balsamina L.)的地径、株高、冠幅、叶面积、花期、花径、一级分枝数、二级分枝数、一级分枝部位高和二级分枝部位高10个重要形态性状与花朵数的关系差异进行了相关性及通径分析,为凤仙花栽培与性状选择提供科学基础。结果表明:30cm×30cm种植的凤仙花的一级分枝数、二级分枝部位高都与花朵数呈显著正相关,地径、冠幅、二级分枝数与花朵数呈极显著正相关,对花朵数的直接效应大小顺序为:二级分枝数>一级分枝数>花径>花期;50cm×50cm种植的凤仙花,其地径、冠幅和二级分枝数都与花产量呈显著正相关,对花朵数的直接效应大小顺序为:二级分枝数>冠幅。二级分枝数对两种密度栽培的凤仙花花产量都起着重要作用。不同种植间距下凤仙花采用了不同的适应方式以获得最大花朵数目,进而获得最大数量的种子,获得较多的繁殖机会。在30cm×30cm下,是通过获得较多一级分枝数;在50cm×50cm下,是通过增加冠幅来产生较大花产量,而且与前者相比,植株茎秆粗壮,对霜霉病的抗性也强,因此,在栽培中,应以适合的低密度栽培比较好。     

窄萼凤仙花化学成分的研究

首次从窄萼凤仙花(Impatiens stenosepala Pritz.ex Diels)中分离得到九个化合物,通过波谱学方法分别鉴定为槲皮素(1)、山柰酚(2)、阿魏酸(3)、对羟基苯甲酸(4)、4’-OH黄芩素(5)、洋芹素(6)、2,5,7,8-四羟基萘醌(7)、5,8-二羟基萘醌(8)及东莨菪素(9)。     

海南凤仙花与龙州凤仙花花的形态补充描述

凤仙花属植物的花部形态历来是该属的属下划分及种间界定的关键性状,基于大量的有花标本及野外实地调查,并参照了模式标本对海南凤仙花和龙州凤仙花的花部形态进行了补充描述。     

Intermediate symmetry in lawsone biosynthesis

Feeding experiments in Impatiens balsamina have established that 2-¹⁴C-acetate predominantly labels C-2 of lawsone. This finding confirms previous biosynthetic postulates, indicates that no symmetrical intermediate is involved in lawsone biosynthesis, and sheds light on the final steps in that process. The experimental methods that have been employed in this series of studies are also described in detail.