珙桐传粉诱物Ⅰ.花色

珙桐(Davidia involucrata)是中国特有的珍稀濒危植物。目前对珙桐的研究主要集中在珙桐的形态描述、地理分布和种群和群落生态以及引种繁殖等方面。对其传粉生物学等的研究未见报道。花色一直被认为是吸引传粉者的诱物之一。传粉生态学家多利用滤镜、摄像等技术或行为学的方法研究花色与传粉者间的关系。黄酮类是花内色素中最重要的一类物质,并且已经有了成熟的提取分离方法。但还没有人具体地对它的变化与传粉者的访花关系进行研究。该文测定了各个花期的珙桐花序苞片、雄蕊和叶中的总黄酮含量及其组分变化,并对各个时期传粉者的传粉频率进行了观察。结果表明,随着花的发育,苞片、雄蕊和叶中的总黄酮含量都在下降,在雌蕊期膜翅目昆虫访问率高,但没有鞘翅目昆虫。此时黄酮可能同时起到了吸引和防御传粉者的作用。有几个黄酮组分含量在总黄酮中的比率上升,另有几个下降,增加了花与背景叶的对比度,可能强化了吸引传粉者的能力。     

Intraspecific and Interspecific Competition in Davidia involucrata (Davidiaceae) Community

Davidia involucrata was a rare valuable and endangered plant in China. In order to study neighborhood competition effects, the intraspecific and interspecific competion intensity in Davidia involucrata community in Wolong Nature Reserve was analyzed quantitatively by using Hegyi individual tree competition index model. And the morphological characteristics of Davidia involucrata were investigated under different neighborhood competition intensity . The results showed that the competition intensity in Davidia involucrata decreased gradually with the increasing of forest tree diameter class and the intraspecific competition in Davidia involucrata was more intensive than interspecific competition. The order of the intraspecific and interspecific competition intensity at the community level was: intraspecific > Lindira pulcherrima > Juglanscathayensis> Cornus controversa > Davidia involucrata var. vilmoriniana > Phoebe neurantha >Symplocos botryantha Franch>Acer oliverianum > Prunus branchypoda > Cyclobalanopsis oxyodon . The relationship between competition intensity and individual growth of objective tree closely followed the following equation: CI = AD^{- B} . The change in competition intensity is very small when the diameter of the objective tree reaches 30 cm . The model can stimulate and predict the intraspecific and interspecific competition efficiently. The morphology of Davidia involucrata , such as stepwise bifurcation ratio 1∶2, branching angle, average branch and current-year branch lenghth of the main stem in different strata , was modified under differentcompetition intensity. The plasticity of substrate branching angle , substrate average branch length and substrate currentyearbranch length was very obvious in response to different neighborhood competion intensity. That suggests Davidia involucrata can improve its capacity to explore the resource and adapt to different habitats through morphological changes .     

珙桐种质资源保存样本策略的研究

珙桐 (Davidiainvolucrata) 是我国特有的珙桐科单型属植物, 起源古老, 是第三纪热带植物区系的孑遗种, 被列为国家一级保护植物。利用RAPD技术, 通过 11个多态引物对 5个天然珙桐种群的遗传多样性、种群内和种群间的遗传变异进行了研究。结果表明 :珙桐天然种群具有丰富的遗传多样性, 但群体间的差异明显, 2 6 %的遗传变异存在于群体间。研究将珙桐划分为东南部和西北部两大种源区。通过对珙桐群体间及群体内的聚类分析, 结合遗传标记的捕获曲线研究提出了珙桐种质资源保存的样本策略。原地保存可以选择甘肃文县、四川峨眉山和贵州梵净山 3个种群作为保存对象, 每个群体保存面积 3hm2 以上 ;异地保存应抽取甘肃文县、四川峨眉山、湖北神农架、贵州梵净山等 4个群体, 每个群体抽样 30个以上个体, 株间最小间距 30m以上, 共计保存 15 0个个体, 分别在东南部和西北部建立一个异地保存点。     

Study on Chemical Components of Davidia involucrata Baill. Native to China

Six compounds have been isolatea from the branch of Davidia involucrata Baill which is native to China. Their structures were identified as taraxerone (D1), taraxerol (D2), β-sitoste- rol (D3), 3′-O-methyl- 3, 4-O, O-methylideneellagic acid (D4), 3, 3′, 4-5-trimethylellagic acid (D5) and ellagic acid (D6) by means of chemical methods and IR 1H-NMR, MS, respectively.     

An evaluation of four threshold selection methods in species occurrence modelling with random forest: Case studies with Davidia involucrata and Cunninghamia lanceolata

Aims Predictive species distribution models (SDMs) are increasingly applied in resource assessment, environmental conservation and biodiversity management. However, most SDM models often yield a predicted probability (suitability) surface map. In conservation and environmental management practices, the information presented as species presence/absence (binary) may be more practical than presented as probability or suitability. Therefore, a threshold is needed to transform the probability or suitability data to presence/absence data. However, little is known about the effects of different threshold-selection methods on model performance and species range changes induced by future climate. Of the numerous SDM models, random forest (RF) can produce probabilistic and binary species distribution maps based on its regression and classification algorisms, respectively. Studies dealing with the comparative test of the performances of RF regression and classification algorisms have not been reported.
Methods Here, the RF was used to simulate the current and project the future potential distributions of Davidia involucrata and Cunninghamia lanceolata. Then, four threshold-setting methods (Default 0.5, MaxKappa, MaxTSS and MaxACC) were selected and used to transform modelled probabilities of occurrence into binary predictions of species presence and absence. Lastly, we investigated the difference in model performance among the threshold selection methods by using five model accuracy measures (Kappa, TSS, Overall accuracy, Sensitivity and Specificity). We also used the map similarity measure, Kappa, for a cell-by-cell comparison of similarities and differences of distribution map under current and future climates.
Important findings We found that the choice of threshold method altered estimates of model performance, species habitat suitable area and species range shifts under future climate. The difference in selected threshold cut-offs among the four threshold methods was significant for D. involucrata, but was not significant for C. lanceolata. Species’ geographic ranges changed (area change and shifting distance) in response to climate change, but the projections of the four threshold methods did not differ significantly with respect to how much or in which direction, but they did differ against RF classification predictions. The pairwise similarity analysis of binary maps indicated that spatial correspondence among prediction maps was the highest between the MaxKappa and the MaxTSS, and lowest between RF classification algorism and the four threshold-setting methods. We argue that the MaxTSS and the MaxKappa are promising methods for threshold selection when RF regression algorism is used for the distribution modeling of species. This study also provides promising insights to our understanding of the uncertainty of threshold selection in species distribution modeling.     

新疆雪莲体细胞胚胎发生

通过体细胞胚胎发生途径实现了新疆雪莲（Saussurea involucrata Kar．et Kir．）的植株再生。选用新疆雪莲子叶为外植体,接种于MS＋0．5mg·L^-12,4-D＋0．05—1mg·L^-1BA的固体培养基上,进行愈伤组织的诱导。从第1次继代培养的愈伤组织中挑选出黄绿色、颗粒状、质地致密的腔陛愈伤组织,转移到含0．05—0．1mg·L^-1 2,4-D的MS液体培养基中进行悬浮培养,20天后可分化产生大量球形胚。继代过程中相继加入PEG和GA3,可以促进体细胞胚的分化和生长。体细胞胚在含有5mg·L^-1 GA3的MS固体培养基上,可发育成完整的植株。     

Relationships between the demography and distribution of two bird-dispersed plants in an island archipelago

Aim I evaluated relationships between the demography and distribution of two bird‐dispersed shrubs in an island archipelago to better understand the life history precursors of different island distributional patterns. Location Barkley Sound, Vancouver Island, British Columbia, Canada (48°80′ N, 125°20′ W). Methods The abundance and occurrence of Lonicera involucrata Rich. (Caprifoliaceae) and Ribes divaricatum Dougl. (Grossulariaceae) were measured on 69 islands measuring between 25 and 800 m². Light and soil conditions were quantified to broadly characterize changes in environmental conditions with island area and isolation. Several experiments and field observations were conducted to evaluate the life history response of each species to changes in island environments. Results Lonicera showed a typical island distribution; it increased in abundance and occurrence with island area. Ribes had a more unusual distributional pattern; it showed no differences in occurrence or abundance with island area. The distribution of both species was unrelated to island isolation. Small islands had less soil and more light than large islands, while environmental conditions were unrelated to island isolation. Lonicera had higher seed germination rates and adult survivorship in large island environments, but similar rates of seed dispersal, seedling survivorship and sapling survivorship in large and small island environments. Ribes had similar rates of seed dispersal, germination and adult survivorship in large and small island environments. However, slightly higher seedling survivorship in large island environments was offset by decreased sapling survivorship. Conclusions Demographic advantages accrued at particular life history stages were either enhanced (Lonicera) or erased (Ribes) at other life history stages. Nevertheless, overall life history trends were consistent with distributional patterns, and suggest different suites of life history characteristics promote different island distributions.     

新疆雪莲新的内切几丁质酶类冷诱导基因的分离、克隆和测序

通过RT-PCR技术,从经低温驯化的新疆雪莲的叶片中分离克隆了1个新的基因.实验证明,此基因的转录是由低温诱导激活,且随着雪莲低温驯化时间的推移,转录本的量明显增加.测序结果显示,此基因全长643 bp,编码200个氨基酸.序列分析发现,此基因属于Ⅱ类内切几丁质酶基因.初步预测此基因的编码产物可能具有抗冻活性.     

A New Phenolic Constituent and a Cyanogenic Glycoside from Balanophora involucrata (Balanophoraceae)

Balanophora involucrata Hook .f. & Thomson (Balanophoraceae) is a parasite plant often growing on the roots of leguminous plants. The whole herb has been used medicinally for the treatment of irregular menstruation, cough, hemoptysis, traumatic injury and bleeding, dizziness and gastralgia in Yunnan Province, China. The 2,2‐diphenyl‐2‐picrylhydrazyl (DPPH) assay on the 60% aq. acetone extract of the fresh whole plant of B. involucrata showed considerable radical‐scavenging activity (SC₅₀ 15.3 μg/ml). Further purification on the extract led to the isolation of one new phenolic glycoside, sieboldin‐3′‐ketocarboxylic acid ( 1 ), and one new cyanogenic glycoside, proacacipetalin 6′‐O‐β‐D ‐glucopyranoside ( 2 ), together with 26 known compounds including three 4″‐O‐galloyl and 2″,3″‐O‐(S)‐hexahydroxydiphenoyl (HHDP) derivatives of dihydrochalcone glucosides, seven hydrolyzable tannins, and alkane glycosides. The cyanogenic compound isolated from the Balanophoraceae family for the first time might be a signal molecule between B. involucrata and its hosts. The free‐radical‐scavenging activity of the isolated compounds was also examined by DPPH assay.     

梵净山自然保护区珙桐萌蘖繁殖在种群数量中的作用

为探讨梵净山自然保护区珙桐(Davidia involucrata)的繁殖策略,揭示萌蘖苗和实生苗在维持种群数量中的作用。采用每木调查法调查贵州省梵净山自然保护区标水岩珙桐种群,根据调查数据绘制径级结构图。以珙桐径级结构代替年龄结构,采用匀滑技术分别编制了萌蘖苗和实生苗种群静态生命表,并绘制存活曲线、死亡率曲线、消失率曲线及4个生存函数曲线。结果显示:(1)珙桐种群年龄结构存在一定的波动性,按萌蘖苗统计则幼龄个体占78.78%,按实生苗统计则幼龄个体占21.45%,两种统计的珙桐种群的生存曲线接近于DeeveyⅡ型。(2)珙桐种群整体是增长的,萌蘖苗V_(spi)高于V_(sepi)(6.50%>2.30%)。(3)珙桐种群生存率呈单调下降趋势,萌蘖苗较明显。(4)珙桐种群累计死亡率呈单调上升的趋势,萌蘖苗更明显。(5)珙桐种群生存率和消失率曲线呈单调上升趋势,萌蘖苗和实生苗基本一致。标水岩珙桐种群属于增长型种群,存活曲线为DeeveyⅡ型,后期种群保持稳定,萌蘖繁殖有利于维持种群数量,在维持种群稳定中具有十分重要的作用。