Cycas necrotic stunt virus isolated from gladiolus plants in Japan

An undescribed spherical virus ca. 30 nm in diameter was isolated from gladiolus (Gladiolus spp.) plants in Japan. The virus had a moderate host range within eight families. Purified virus preparations contained two large RNA components and one coat protein with mobility similar to Cycas necrotic stunt virus (CNSV) from cycas (Cycas revolute). The virus was serologically closely related to CNSV. Its nucleotide sequence of the coat protein gene had 89% common identity with that of CNSV. These results indicated that the virus isolated from gladiolus is a new strain of CNSV. The nucleotide sequence data reported are available in the DDBJ/EMBL/Gen Bank databases under the accession number AB237656.     

珍稀濒危植物德保苏铁迁地保护研究

德保苏铁Cycas debaoensis为中国特有种,国家I级重点保护野生植物。2002年由广西德保引种至桂林植物园。对德保苏铁繁殖特性、生长习性、适应性等进行了研究。结果表明：原产于南亚热带石灰岩土壤条件下的德保苏铁在中亚热带酸性土壤条件下生长良好、开花结实,抗寒性较强。在引种地,成龄植株萌叶期为5-7月,花期5-6月,果熟期11月中旬至下旬。德保苏铁茎干生长缓慢,株高平均增长1．90 cm．a^-1,地径平均增长2．14 cm．a^-1。德保苏铁种子具后熟休眠特性,种子储藏方式以常温湿砂储藏较好,种子萌发率为80％左右。     

尖尾苏铁根系类型与解剖结构研究

研究了尖尾苏铁根系的形态及解剖结构。首次发现苏铁植物的根系属须根系，全部须根膨大成肉质根，同一条肉质根内的原生木质部束呈现二原型至九原型。皮层簿壁细胞多达80层以上，细胞内含丰富的淀粉粒；分泌腔常见。这些发现为揭示苏铁类植物对恶劣环境的适应机制有重要意义。     

贵州苏铁植株体内矿质养分含量特征分析

测定珍稀濒危植物贵州苏铁植株,构建不同组织和器官矿质营养元素的含量,分析矿质营养在体内分布特征及其相关特性,以及结合生长环境土壤特性分析贵州苏铁生长发育对营养需求以及土壤环境供给之间的关系,研究珍稀濒危植物贵州苏铁植株矿质营养含量及与土壤环境的相互作用,为贵州苏铁栽培和物种保护提供参考.结果表明:植株体内N、P元素含量变化较大,4a生植株体内比1 a生积累更多Fe、Mn、Zn、Ga、Mg元素,小孢子叶Zn含量最高,大孢子叶Mn含量最高,雄性叶元素含量高于雌性叶.表明贵州苏铁生长发育过程中生殖生长需要大量种类和数量的矿质营养物质,同时也证明了营养生长物质服务于生殖生长.在栽培生产中除了选择栽培基质与原生地大致相同满足植株的营养生长外,还更应注重在生殖时期对矿质营养的补给,满足植物生殖生长对矿质营养的需求.     

澜沧江中下游篦齿苏铁种群结构及其保护对策

对澜沧江中下游糯扎渡水电站工程枢纽区和库区内篦齿苏铁的生境、种群结构进行调查研究。结果表明,篦齿苏铁在澜沧江干流的两岸分布不均匀,右岸占48.37%,左岸占4.26%,支流占46.37%;主要生长在落叶季雨林下,以半阴半阳坡较多,占总株数401株的47.85%。调查区域内篦齿苏铁种群密度很低,平均约1株/hm2。由于人为采挖严重,导致其种群大小级结构不完整,成年个体较少,缺乏Ⅲ级个体,以Ⅰ级、Ⅱ级幼小个体较多,占32.21%。种群内开花结实植株少,仅发现5株开花,2株结实,但其单株自然结实率较高。目前该种群面临的威胁有：人为采挖;人类生产和建设活动使其生境丧失及生境退化严重;啮齿动物的啃食。使该区域苏铁种群密度急剧减小的主要原因是各种人为干扰,而非自然因素。指出应加大对篦齿苏铁野生资源的调查和保护力度,就地保护和迁地保护相结合,并开展人工繁殖、遗传多样性和生理生态方面的研究,以便更加科学、合理地制定其保护措施。     

贵州苏铁组织培养研究

分别以当年生贵州苏铁无菌培养植株的根、茎干和鳞片为外植体,MS为基础培养基,研究了生长素种类和浓度对外植体诱导效果的影响。     

贵州苏铁野生居群径级构件与种群动态

研究贵州苏铁野生居群的种群构件特性,通过数学推理种群构建因子球茎直径、叶片数量和球茎高度以及根系之间的相互关系,结果认为,从种群径级构件分析,自然状况下贵州苏铁老、中、青年龄结构合理,自然状态下种群能够实现物种的健康延续发展.采用最小二乘法拟合种群构件之间的关系,有助于在野外及时准确地认识贵州苏铁的个体特性及其栽培种植管护.     

Distribution of free and glycosylated sterols within Cycas micronesica plants

Flour derived from Cycas micronesica seeds was once the dominant source of starch for Guam's residents. Cycad consumption has been linked to high incidence of human neurodegenerative diseases. We determined the distribution of the sterols stigmasterol and β-sitosterol and their derived glucosides stigmasterol β-d-glucoside and β-sitosterol β-d-glucoside among various plant parts because they have been identified in cycad flour and have been shown to elicit neurodegenerative outcomes. All four compounds were common in seeds, sporophylls, pollen, leaves, stems, and roots. Roots contained the greatest concentration of both free sterols, and photosynthetic leaflet tissue contained the greatest concentration of both steryl glucosides. Concentration within the three stem tissue categories was low compared to other organs. Reproductive sporophyll tissue contained free sterols similar to seeds, but greater concentration of steryl glucosides than seeds. One of the glucosides was absent from pollen. Concentration in young seeds was higher than old seeds as reported earlier, but concentration did not differ among age categories of leaf, sporophyll, or vascular tissue. The profile differences among the various tissues within these organs may help clarify the physiological role of these compounds.     

珍稀植物攀枝花苏铁ISSR扩增条件的优化

在利用ISSR技术对攀枝花苏铁（Cycas panzhihuaensis）种质资源遗传多样性进行研究的实验过程中, 对影响PCR扩增效果的一些因素如DNA的提取、模板DNA质量浓度、Taq酶用量、引物用量、dNTP的用量以及退火温度等指标进行筛选和优化。试验结果表明,20μl的反应体系中采用15~25ng 的模板DNA、2.0~2.5mmol/L的Mg2 + 浓度、0.2mmol/L的dNTPs、0.2μmol/L ISSR 引物、0.2U Tag DNA 聚合酶、48 ℃~55 ℃(退火温度随引物不同而定)的复性温度,以及35个循环数为攀枝花苏铁ISSR—PCR 扩增条件的最佳选择。攀枝花苏铁ISSR—PCR 扩增条件的优化为进行攀枝花苏铁种群间遗传分化的研究奠定了基础。     

苏铁叶枯病病原菌鉴定

近年在贵州省苏铁各栽培地发现一种叶枯病害,为明确其致病菌,采集苏铁叶枯病叶片样本数份,并对病原菌进行形态观察、致病性测定及r DNA-ITS序列分析。结果表明:经分离纯化获得的病原菌,通过柯赫氏法则,接种后出现的病害症状与直接采集到的病害标样症状一致,确定其为致病菌;对病原菌进行传统的形态学观察,结果显示病原菌分生孢子器和分生孢子的形态与拟茎点霉一致;将待测菌株r DNA-ITS序列与Gen Bank中相关菌株ITS序列进行同源性比较,结果显示该菌株与Phomopsis vaccinii(Gen Bank登陆号为:KC488259,JX846914)的同源性达97%。结合病原菌形态学特征及株r DNA-ITS序列(Gen Ban登录号:JN417709)特征,确定苏铁叶枯病病原菌为Phomopsis cycadis.