Some Problems in the Assay Method of HMG-CoA Reductase Activity in Sweet Potato in the Presence of Other HMG-CoA Utilizing Enzymes

In addition to HMG-CoA reductase, another HMG-CoA utilizing enzyme is present in the Mt fraction of sweet potato root tissue and its activity interferes with the assay to HMG-CoA reductase activity.     

中国豆科植物新资料

<正>一、虫豆属 Atylosia Wight et Arn,1.白蔓草虫豆 新变种图1Atylosia scarabaeoidea(Linn)Benth ,var aryrophylla Cheng f,var ,nov     

Physiological aspects of Taxus brevifolia seeds in relation to seed storage characteristics

Water relations, desiccation tolerance and longevity of Taxus brevifolia (Nutt.) seeds were studied to determine the optimal stage of development and storage conditions for seeds of this species. Seeds equilibrated to a range of relative humidities (RHs) had unusually low water contents which can be accounted for by the high lipid content of gametophyte tissues (71% of the dry mass). Water relations of embryonic tissue were more typical of those reported for other seed species. The water content below which freezing transitions were not observable in the embryo was ca 0.24 g H₂O (g dry weight)⁻¹ (g g⁻¹) for all maturity classes studied. Embryos did not achieve significant levels of desiccation tolerance (survival to water contents less than 0.5 g g⁻¹) until the latter stages of development when dry matter was maximal. Mature embryos could be dried to 0.025 g g⁻¹ (seed water content of 0.010 g g⁻¹) with no loss of viability. Thus, at the latter stages of development, embryo water content could be optimized to avoid both desiccation and freezing damage. Survival of mature seeds declined over a 2-year period when seeds were stored at temperatures between 5 and 35°C and RHs between 14 and 75%, corresponding to seed water contents between 0.015 and 0.07 g g⁻¹. The deterioration rate was slowest for seeds stored at the lowest RH and temperature. Our data indicate that seeds of Taxus brevifolia show orthodox rather than recalcitrant storage characteristics, but that the optimum water content for storage was extremely low. The results suggest that even if stored at optimal water contents and low temperatures, T. brevifolia seeds will be relatively short lived. The high quantity of lipids or reducing sugars may be contributing factors in the poor storage characteristics.     

中国红豆杉内生细菌的分离鉴定及活性研究

从中国红豆杉的茎中分离得到两株内生细菌G18、F19,通过生物学特性和16S rDNA序列分析,初步鉴定这两株菌分别为假单胞菌属(Psudomonas)和寡养单胞菌属(Stenotrophomonas)细菌.活性研究表明,G18、F19发酵液均对3种病原细菌有抑制作用,分剐对棉花黄萎病菌(Verticillium dahliae)和柑橘炭疽病菌(Colletotrichum gloeosporioides)有较强的抑制作用.G18和F19分别能降解水杨酸和敌敌畏.     

云南含笑花粉萌发研究

应用离体培养和人工授粉的方法对云南含笑花粉的萌发进行了研究。栽培和野生云南含笑花粉的萌发率有很大的差异,分别为20％和90％。首次报道了云南含笑的花粉粒在离体培养基上萌发2条花粉管的现象。云南含笑花粉在灰岩含笑花柱头上的萌发率和萌发时间与离体培养基上的相同,表明灰岩含笑的柱头对云南含笑的花粉没有排异现象。     

元宝山南方红豆杉种群分布格局及动态

采用相邻格子样方法取样数据,应用方差 /均值比的t检验法、负二项参数、格林指数、Cassie指标、扩散型指数、丛生指标、平均拥挤度和聚块性指数等方法及分布模型,研究了南方红豆杉种群的空间分布格局及其动态.结果表明,南方红豆杉种群空间格局为集群分布,从幼苗到大树,其集群程度减小,大树呈随机分布.     

云南红豆杉紫杉烷2α-O-苯甲酰转运酶基因的克隆及定性

通过RACE技术,克隆了云南红豆杉紫杉烷2α-O-苯甲酰转运酶基因(TyTBT),该酶催化2-去苯甲酰-7,13-二乙酰巴卡亭Ⅲ生成7,13-二乙酰巴卡亭Ⅲ,是紫杉醇合成途径中的关键酶之一.TyTBT基因cDNA全长1481 bp,含有1 320 bp的开放读码框,编码440个氨基酸的多肽,分子量为50 050 Da,等电点为6.17.氨基酸序列比对表明TyTBT同植物酰化酶家族的其它成员有较高的相似性,超过67%,同东北红豆杉和曼地亚红豆杉的紫杉烷2α-O-苯甲酰转运酶氨基酸序列的一致性和相似性达到最高,分别为95%和96%.广泛地比对分析证明这种较高的相似性在红豆杉属的其它酶家族中具有普遍性,进化树分析表明同东北红豆杉和曼地亚红豆杉的紫杉烷2α-O-苯甲酰转运酶(TBT)的相似性高于紫杉醇合成途径中的其它酰化酶.     

红豆杉迁地保护中天然种群的形成

０年代自庐山植物园引种栽培于南京中山植物园的１１株红豆杉〔Ｔａｘｕｓｃｈｉｎｅｎｓｉｓ（Ｐｉｌｇｅｒ）Ｒｅｈｄ．〕幼苗组成的栽培种群,在４０多年的迁地保护过程中,生长发育正常,且在邻近的自然生境中繁衍出一个含有４６１株幼苗及小树的天然红豆杉种群,树高１０～３４５ｃｍ,树龄１～１５年,主要散生于海拔３５～６０ｍ的山坡麻栎群落及山溪边的枫杨群落中。栽培种群中雌树５株,雄树６株,栽培红豆杉在３０年左右开花结实。该天然种群的形成过程是：红豆杉成熟种子被鸟类取食,其肉质假种皮被消化后,在鸟类的栖息范围内随着鸟粪被随机散布,经过生境选择、适应,于适宜的生境条件下萌发生长成幼苗及小树。此外,讨论了天然红豆杉种群的形成和发展,对于植物迁地保护研究与实践的重要意义。     

Superoxide anion burst and taxol production induced by Ce in suspension cultures of Taxus cuspidata

Generation of reactive oxygen species (ROS) induced by Ce⁴⁺ in suspension cultures of Taxus cuspidata was investigated. The burst of superoxide anions (O₂√⁻) occurred rapidly after the addition of Ce⁴⁺ and reached maximum at 4.3 h, while the total level of the cellular reactive oxygen species maintained unchanged. The intracellular superoxide dismutase (SOD) and catalase (CAT) were activated while the intra/extracellular peroxidases (PODs) were inhibited accompanying the O₂√⁻ burst. The pretreatment of the suspension cultures with diphenylene iodonium (DPI), a suicide inhibitor of the NADPH oxidase, blocked the O₂√⁻ burst, inhibiting the cell apoptosis and taxol production induced by Ce⁴⁺. These results show that NADPH oxidase played a key role in O₂√⁻ burst and O₂√⁻ served as a mediator of Ce⁴⁺ for cell apoptosis and taxol production. The pretreatments of the suspension cultures with anthracene-9-carboxylate, an ion-channel blocker, nifedipine, a Ca²⁺-channel blocker, neomycin, a phospholipase C (PLC) inhibitor, or suramin, a G-protein inhibitor, decreased O₂√⁻ burst induced by Ce⁴⁺. It is thus inferred that Ce⁴⁺-induced O₂√⁻ burst, which mediated cell apoptosis and taxol production by activating the ion-channels, PLC, G-proteins and NADPH oxidase.     

Mussaenda yunnanensis sp. nov. (Rubiaceae), a new functionally dioecious species from Yunnan,China

Mussaenda yunnanensis, a new dioecious species of Rubiaceae from Yunnan Province, China, is described and illustrated. The new species can be recognized by its slender stem, congested‐cymose inflorescences and long corolla tubes. Differences between M. yunnanensis and two morphologically similar species (M. pubescens and M. antiloga) are presented. We also provide a key to all dioecious species of Mussaenda in China. The delimitation of the new species is further supported by molecular phylogenetic analyses based on eight plastid loci.