Life history variation between species of the relictual genus Borderea (Dioscoreaceae): phylogeography, genetic diversity, and population genetic structure assessed by RAPD markers

The genus Borderea consists of two species, B. pyrenaica and B. chouardii, taxa which have been previously considered as conspecific due to their overall close morphology. These two sole species of the rare genus of Dioscoreaceae are endemic to the Pyrenees (Spain, France). This mountain range likely operated as a refugium for these plants during the last glaciations. B. chouardii is only known from a single population in the Spanish Prepyrenees and has been classified as at risk of extinction in the Red List of Endangered Species (IUCN); B. pyrenaica shows a narrow distribution range in the central Pyrenees and Prepyrenees. We analysed genetic variation, population structure and differentiation in these two taxa using RAPD markers. Our study was conducted on the same seven populations for which very low levels of genetic differentiation were detected previously through allozyme analysis. By contrast, high levels of genetic variability were detected through the RAPD hypervariable markers. Twelve RAPD primers produced 112 distinct bands in the 397 surveyed individuals, totalling 395 different RAPD phenotypes. Only four bands were monomorphic across all samples of Borderea, whereas 21 of the polymorphic bands were species‐specific (20 for B. chouardii, and one for B. pyrenaica). The largest genetic distances were those between the B. chouardii and the B. pyrenaica phenotypes. An analysis of molecular variance showed greater variance between groups (B. chouardii vs. B. pyrenaica, 76.08%) than within groups (3.60%). RAPD band specificity, phenotypic distances, and the partitioning of variance all support the taxonomic separation of the two species. Statistical evaluation of within‐ and among‐population RAPD genetic variability in B. pyrenaica showed that genetic variability was higher within populations (>80%) than among them. No clear pattern of RAPD differentiation could be observed among the six studied populations of this taxon though slight differences in genetic diversity could be observed in the more isolated Prepyrenean populations compared with the more widespread Pyrenean ones. These results suggest a recent postglacial origin of the present B. pyrenaica populations. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80 , 483–498.     

Temperature dependence of seedling establishment of a perennial, Dioscorea tokoro

The temperature dependence of seed germination and seedling growth was analyzed in Dioscorea tokoro, an East Asian summer-green perennial. Seeds were able to germinate fully only at 11°–20°C. At around 17°–20°C the first leaf petiole of the seedling elongated and quickly set the first leaf blade at a position enabling photosynthesis. At temperatures higher than 20°C petiole elongation was retarded, and seedlings formed a rhizome and established as a perennial. The rhizome size increased with temperature up to 29°C. Thus, during growth immediately after germination, temperature appears to be a key factor in determining whether the plant establishes as a perennial or grows rapidly without rhizome thickening. Received: April 6, 2001 / Accepted: September 14, 2001     

The cytotoxicity of protoneodioscin (NSC-698789), a furostanol saponin from the rhizomes of Dioscorea collettii var. hypoglauca, against human cancer cells in vitro

Protoneodioscin (NSC-698789) is a furostanol saponin isolated from the rhizomes of Dioscorea collettii var. hypoglauca (Dioscoreaceae), a Chinese herbal remedy for cancer treatment. Our studies showed that protoneodioscin is cytotoxic against most cell lines from leukemia and solid tumors in the NCI's (National Cancer Institute, USA) anticancer drug screen. Leukemia, CNS cancer, and prostate cancer are the most sensitive subpanels to protoneodioscin, while melanoma, ovarian cancer, and renal cancer are less sensitive. The preliminary animal studies showed that the maximum tolerant dose of protoneodioscin was 600 mg/kg to mice. Based on an analysis of the COMPARE software with protoneodioscin as a seed compound, no compounds in the NCI's database have similar cytotoxicity patterns to those of protoneodioscin, indicating a potentially novel mechanism of anticancer action involved.     

Rapidly screening of α-glucosidase inhibitors from Dioscorea opposita Thunb. peel based on rGO@Fe3O4 nanocomposites microreactor

Present study aimed to immobilise the α-glucosidase on suitable supports to construct enzymatic microreactors and their subsequent applicability in efficient inhibitor screening from the Chinese Yam (Dioscorea opposita Thunb.) peel. A type of lamellar and porous composites (rGO@Fe₃O₄) were synthesised with a facile one-step solvothermal method and employed as carriers to construct enzymatic microreactors for screening α-glucosidase ligand from the Chinese Yam peel in league with the high performance liquid chromatography and mass spectrometry (HPLC-MS). The immobilisation amount of α-glucosidase on rGO@Fe₃O₄ under the optimised conditions was about 40?μg α-glucosidase/mg carriers. Furthermore, the binding capacities of screened inhibitors, 2,4-dimethoxy-6,7-dihydroxyphenanthrene and batatasin I, were 35.6 and 68.2%, respectively. Hence, considering their high screening efficiency and excellent magnetic separation ability, these as-prepared nanocomposite consisting of rGO and Fe₃O₄ may be potential supports for the enzyme (such as α-glucosidase) immobilisation for rapid α-glucosidase inhibitors screening from the diverse nature resources.     

Expansion of trait of gibberellin-induced dormancy in the Tertiary relict species of the genus Dioscorea (Dioscoreaceae)

Effects of the application of gibberellin A₃ (GA₃) on sprouting of rhizomes and germination of seeds were tested in five species of the genus Dioscorea which are considered to be Tertiary relicts growing disjunctively in the Appalachians, the Balkans, and the Caucasus. Applied GA₃ at higher than 1 micro;M markedly inhibited sprouting of rhizomes of all species. However, inhibition of seed germination of these species by GA₃ application was not observed. It is hypothesized that before disjunction in the Tertiary period GA-induced dormancy probably prevailed in rhizomes of all members of the genus Dioscorea.     

野生北五味子生物学特性的研究

采用多年全面调查及三年时间定位,定株观测相结合的方法,对野生北五味子生物学特性进行了深入研究。对其开花结实规律;雌雄同株,异株问题,座果率;物候期;种源与质量关系方面均有新发现。     

Development of DNA microsatellite markers in tropical yam (Dioscorea sp.)

We developed new simple sequence repeat (SSR) markers in different species of yam (Dioscorea sp.). A microsatellite‐enriched bank was created from Dioscorea alata, Dioscorea abyssinica and Dioscorea praehensilis. Sixteen polymorphic loci were characterized. Several of these markers are transferable to species of other Dioscorea sections.     

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。     

杜鹃花属照山白叶表皮及花粉形态的研究

利用光学显微镜和扫描电子显微镜对杜鹃花属植物照山白的叶表皮及花粉形态进行了观察,该种的叶表皮细胞表面光滑,胞间界限明显;叶上下表皮均有盾状鳞,上表皮仅有针状毛;气孔器仅见于下表皮,分布稀疏,副卫细胞和保卫细胞表面光滑。扫描电镜下可见该种的花粉为四合花粉,呈正四面体排列,具三沟,表面纹饰为负网状雕纹,局部区域有大颗粒状突起。