Disrupted phylogeographical microsatellite and chloroplast DNA patterns indicate a vicariance rather than long‐distance dispersal origin for the disjunct distribution of the Chilean endemic Dioscorea biloba (Dioscoreaceae) around the Atacama Desert

Aim The Chilean endemic Dioscorea biloba (Dioscoreaceae) is a dioecious geophyte that shows a remarkable 600 km north–south disjunction in the peripheral arid area of the Atacama Desert. Its restricted present‐day distribution and probable Neogene origin indicate that its populations have a history linked to that of the Atacama Desert, making this an ideal model species with which to investigate the biogeography of the region. Location Chile, Atacama Desert and peripheral arid area. Methods Two hundred and seventy‐five individuals from nine populations were genotyped for seven nuclear microsatellite loci, and plastid trnL–F and trnT–L sequences were obtained for a representative subset of these. Analyses included the estimation of genetic diversity and population structure through clustering, Bayesian and analysis of molecular variance analyses, and statistical parsimony networks of chloroplast haplotypes. Isolation by distance was tested against alternative dispersal hypotheses. Results Microsatellite markers revealed moderate to high levels of genetic diversity within populations, with those from the southern Limarí Valley showing the highest values and northern populations showing less exclusive alleles. Bayesian analysis of microsatellite data identified three genetic groups that corresponded to geographical ranges. Chloroplast phylogeography revealed no haplotypes shared between northern and southern ranges, and little haplotype sharing between the two neighbouring southern valleys. Dispersal models suggested the presence of extinct hypothetical populations between the southern and northern ranges. Main conclusions Our results are consistent with prolonged isolation of the northern and southern groups, mediated by the life‐history traits of the species. Significant isolation was revealed at both large and moderate distances as gene flow was not evident even between neighbouring valleys. Bayesian analyses of microsatellite and chloroplast haplotype diversity identified the southern area of Limarí as the probable area of origin of the species. Our data do not support recent dispersal of D. biloba from the southern range into Antofagasta, but indicate the fragmentation of an earlier wider range, concomitant with the Pliocene–Pleistocene climatic oscillations, with subsequent extinctions of the Atacama Desert populations and the divergence of the peripheral ones as a consequence of genetic drift.     

Reproductive biology and pollinators in two enantiostylous Qualea species (Vochysiaceae) in the Brazilian Cerrado

• Enantiostyly is a floral polymorphism in which two floral forms in the same species differ in deflection of the stigma to right or left position. In monomorphic enantiostylous plants, flowers of the two morphs occur within the same individual, usually in the same proportion. In self‐compatible species the function of monomorphic enantiostyly is proposed to increase outcrossing rates and offer a reproductive advantage under pollination limitation. Enantiostylous species are usually self‐compatible and show heteranthery, with poricide anthers and pollen as pollinator reward; however, there are families, such as Vochysiaceae, that have different characteristics.
• We analysed the reproductive system and pollination biology of Qualea parviflora and Q. multiflora, two enantiostylous species from the Brazilian Cerrado that have specific morphological and physiological traits. For this, we characterized flower traits, performed hand pollinations and studied floral visitors.
• We found no differences between morphs in the proportion of flowers, nectar produced or its concentration, pollen quantity and fruit set. Both species were self‐incompatible and quite generalist regarding floral visitors.
• Enantiostyly in self‐incompatible plants seems to confer a reproductive advantage by reducing self‐interference resulting from stigma clogging. This novel result helps to expand our knowledge on this complex floral polymorphism and opens new avenues for future research on this topic.

     

Life history and population dynamics of the Japanese Yam,Dioscorea japonica Thunb.

The adaptive significance of the emergence mode ofDioscorea japonica was studied with respect to initial plant size (seed, bulbil and tuber) and light intensity, using mathematical simulation based on Yokoi's (1976) model. Under 1.5% full sunlight conditions, plants emerging with only one leaf did not develop a shoot system throughout the growing period (Hori and Oshima, 1986). Simulation indicated that, for this species of plant under poor productive conditions, the optimal time for switch-over from the vegetative to reproductive growth phase to maximize the tuber weight at the end of the growing period, occurred immediately following the start of autotrophic growth. By means of shoot growth patterns, small and large size plants acquired the ability of shade tolerance and shade avoidance, respectively. Further, the life history ofD. japonica could be expressed as a flow chart based on plant size and light intensity data.     

小花清风藤的化学成分研究

利用Sephadex LH-20,硅胶柱色谱和硅胶制备薄层色谱等分离方法反复分离纯化,从小花清风藤（Sabia parviflora Wall．ex Roxb）中分离得到9个化合物,通过波谱数据分析分别鉴定它们为二十五烷酸（1）、木栓酮（2）、5-氧阿朴菲碱（3）、3-氧化齐墩果酸甲酯（4）、齐墩果酸（5）、羽扇豆-20（29）-烯-3-酮（6）、羽扇豆醇（7）、β-谷甾醇（8）、脱镁叶绿甲酯酸（9）。化合物2,6、7、9首次从该植物中分离得到。     

Serological detection of yam viruses in farmers' fields in Ogun State,Nigeria

A field survey was conducted in eight local government areas (LGA) of Ogun state, Nigeria to assess the incidence of viral diseases of yams in the areas. Leaf samples were collected from 90 yam plants which were either symptomatic or asymptomatic. These were bulked into 45 during serological tests and the viruses indexed include yam mosaic virus (YMV); Dioscorea alata bacilliform virus (DaBV) and cucumber mosaic virus (CMV). DaBV was the most prevalent virus on the field with incidence of 48.9% (22/45) followed by YMV which occurred in 42.2% (19/45). CMV had the lowest percentage of incidence; 2.2% (1/45). Of all the LGAs visited, Abeokuta north and Abeokuta south had the highest incidence of YMV and DaBV, respectively. Mixed virus infections were also detected.     

Galinsosides A and B,bioactive flavanone glucosides from Galinsoga parviflora

Galinsosides A (1) and B (2), new flavanone glucosides together with two known flavanones, 7,3′,4′-trihydroxyflavanone (3) and 3,5,7,3′,4′-pentahydroxyflavanone (4) have been isolated from an ethyl acetate- soluble fraction of Galinsoga parviflora. Their structures were assigned on the basis of spectral studies. Compound 1 showed significant antioxidant and urease inhibitory activity while compound 2 was moderately active. On the other hand, 2 showed inhibitory potential against α-glucosidase.     

淮山微波真空干燥特性与动力学模型

探索了淮山在不同切分方式、热烫条件、装载量、真空度、转盘转速、温度、切片厚度等干燥条件下的干燥特性,并建立了干燥动力学模型。结果表明:切分方式、装载量、真空度、温度与切片厚度对淮山干燥速率的影响显著。选用6种常用的干燥模型对不同真空度下的试验数据进行非线性回归拟合,并确定了模型参数。结果发现Page模型具有较高的拟合度(R2)与较低的残差平方和,且P <0. 01,说明该模型能较准确地表达和预测淮山微波真空干燥过程的水分变化规律。     

黄独脱毒苗叶片和茎段再生体系的建立

以黄独茎尖再生苗为试材,研究不同因素对黄独脱毒苗叶片和茎段再生体系的影响,以期对黄独脱毒苗的再生体系进行优化。结果表明,叶片和茎段诱导愈伤组织的最佳培养基是MS+KT 2 mg·L^-1+2,4-D 2 mg·L^-1;叶片和茎段诱导愈伤组织的最佳蔗糖浓度分别为30和50 g·L^-1;叶片和茎段在黑暗中较容易诱导出愈伤组织;叶片和茎段愈伤组织分化的最佳培养基是MS+KT 4 mg·L^-1+NAA 0.1 mg·L^-1;继代2次的叶片和茎段愈伤组织较容易分化;黄独不定芽生根的最佳培养基是1/2MS+IBA 0.1 mg·L^-1+NAA 0.5 mg·L^-1+PP₃₃₃ 1 mg·L^-1。本实验成功建立了黄独脱毒苗叶片和茎段的再生体系,为黄独脱毒苗的工厂化生产奠定了技术基础。     

黄独微型块茎低温离体保存的GC/MS代谢组学分析

GC/MS检测方法采用初步探明黄独低温离体保存微型块茎的差异代谢物。与黄独微型块茎25℃离体保存相比较,黄独微型块茎4℃离体保存的差异性代谢物有丙氨酸（Alanine）、儿茶素（Catechin）、N,N-双（2-羟乙基）甲胺（N,N-Di-（2-Hydroxyethyl）-methanamine）、水杨酸（Salicylic acid）、柠檬酸（Citric acid）和山梨糖（Sorbose）等。在黄独微型块茎4℃离体保存中,丙氨酸（Alanine）参与氰基氨基酸代谢;儿茶素（Catechin）参与次生代谢产物生物合成、黄酮类化合物的生物合成和苯丙素的生物合成;水杨酸（Salicylic acid）参与多环芳烃降解、微生物在不同环境中的代谢、植物激素信号转导、次生代谢产物生物合成、二恶英降解、苯丙氨酸代谢、芳烃降解、植物激素生物合成、铁载体组非核糖体肽合成和苯丙素的生物合成等。柠檬酸（Citric acid）参与来自鸟氨酸、赖氨酸和烟酸的生物碱生物合成、组氨酸和嘌呤的生物碱生物合成、微生物在不同环境中的代谢、植物次生代谢产物的生物合成、2-氧代羧酸代谢、萜类和类固醇的生物合成、原核生物固碳途径、次生代谢产物生物合成、来自莽草酸途径的生物碱生物合成、来自萜类化合物和聚酮的生物碱生物合成、柠檬酸循环（TCA循环）、植物激素生物合成、乙醛酸和二羧酸代谢、双组分系统、苯丙素的生物合成以及来自鸟氨酸,赖氨酸和烟酸的生物碱生物合成等。黄独低温离体保存微型块茎差异代谢物的初步发现为进一步了解其低温离体保存的分子机制奠定了基础,也为低温离体保存黄独微型块茎的破除休眠以及其后续萌发提供了理论依据。