Growth kinetics of glucose-limited petunia hybrida cells in chemostat cultures: Determination of experimental values for growth and maintenance parameters

With glucose-limited continuous cultures of Petunia hybrida six steady states were obtained at specific growth rates varying from 0.0035 to 0.012 h(-1) (corresponding with culture residence times varying from 285 to 85 h). The macromolecular and the elemental biomass composition which were determined in four steady states showed no major differences over the range of growth rates examined. During all six steady states specific subtrate and oxygen consumption as well as biomass and extracellular product formation rates were monitored. Moreover the specific activities of the mitochondrial cytochrome and alternative pathway were determined and used to estimate specific adenosine triphosphate (ATP) production rates. Data thus obtained were used in the determination of maintenance and true growth yield parameters. For the maintenance on glucose and ATP values of 0.0070 C-mol/C-mol/h and 0.034 mol/C-mol/h were obtained, respectively. True yields of biomass on glucose and ATP were 0.50 C-mol/C-mol and 0.28 C-mol/mol, respectively. (c) 1995 John Wiley & Sons, Inc.     

五唇兰对PEG模拟的干旱胁迫响应研究

为了解干旱对五唇兰(Phalaenopsis pulcherrima)生长的影响,以聚乙二醇(PEG)溶液模拟干旱胁迫,对其叶片的光合色素、渗透调节物质和非结构碳水化合物(NSC)含量变化进行研究。结果表明,随着PEG浓度增加,五唇兰植株含水量和鲜质量逐渐下降,以PEG为13.75%～14.84%时最显著。PEG处理显著降低叶片的叶绿素a和b含量。随着植株含水量的降低,叶片可溶性蛋白、淀粉(St)含量均呈下降趋势,可溶性糖(SS)含量、NSC和SS/St均呈先升后降的趋势。因此,干旱胁迫会影响五唇兰植株的含水量和光合产物的积累;在较低程度干旱胁迫下,可溶性糖在抗旱响应中发挥主要作用;随着干旱胁迫程度加深,五唇兰的生理代谢受到严重影响。     

16 个蝴蝶兰品种 EST-SSR 遗传多样性分析

利用 NCBI 上提供的8 188 条蝴蝶兰 EST 序列开发 EST-SSR 引物,用来分析市场上较常见的 16 个蝴蝶兰栽培品种的遗传多样性。结果成功开发出了 9 对多态性引物,这 9 对引物在 16 个蝴蝶兰品种上共检测出 45 个等位基因,每对引物可检测等位基因2 ~ 12 个,平均为 5 个;SSR 引物多态性信息量 (PIC) 变化范围为 0.527 ~ 0.981,平均为 0.755;16 个蝴蝶兰品种间的遗传相似系数在 0.550 ~ 0.875 之间,平均值为 0.728,表明供试品种间的亲缘关系较近。UPGMA 聚类分析结果表明,在遗传相似系数为 0.73 处可将 16 个蝴蝶兰品种分为四大类,第Ⅰ类包括满天红、巨宝红玫瑰等 10 个品种,第Ⅱ类包括夕阳红、富乐夕阳、昌新皇后和新原美人 4 个品种,第Ⅲ类包括萨拉黄金 1 个品种,第Ⅳ类包括台湾阿妈 1 个品种,聚类结果与花色特征比较一致。该研究结果对蝴蝶兰品种选育有一定参考价值。     

Acid-stable α-Amylase of Black Aspergilli

Some general properties of the acid-stable dextrinizing amylase of black Aspergillus were investigated comparing with those of Taka-amylase A. The mode of action on starch of this amylase was quite similar to that of Taka-amylase A. Saccharifying degree at red point in starch-iodine color reaction was 5.1% and the limit of starch saccharification was a little over 40 per cent calculated as glucose with both amylases. Maltase activity was absent. Degradation products in the course of starch hydrolysis were also quite similar and they mutarotated downward. So this amylase was decided to be α-type. Thermal stability of the acid-stable α-amylase was higher than that of Taka-amylase A. Its acid stability was much higher than that of Taka-amylase A. Taka-amylase A was inactivated completely at pH 2.2, 37°C, for 30 min, but the acid-stable α-amylase retained 87% of its original activity.

From the amylase preparation of black Aspergillus acid-stable α-amylase and acidunstable α-amylase were separated by gel filtration on sephadex G-100 column. From the acid-unstable α-amylase fraction this enzyme was purified by fractionations with rivanol and acetone, and finally obtained as a homogeneous protein after gel filtration with sephadex G-50. Comparison of some general properties between the two α-amylases was carried out. Catalytic action was quite similar with both enzymes, but dextrinizing unit per mg enzyme protein of the acid-unstable α-amylase was about 5.6 times as large as that of the acid-stable α-amylase. The acid-unstable α-amylase was less heat-stable than the acid-stable α-amylase. Acid stability and pH-activity curve were compared with both α-amylases. High stability of the acid-stable α-amylase in acidic condition was observed, but, in alkaline range, it was more sensitive than the acid-unstable α-amylase.     

Cloning and characterization of PhPI9 involved in floral development from Phalaenopsis Orchid

In the attempt to discover new genes involved in the floral development in monoeotyledonousin species,we have cloned and characterized the homologous PISTALLATA-like (PI-like) gone from Phalaenopsis hybrid cultivar named PhPI9 (Phalaenopsis PI STILLATA # 9).The eDNA of PhPI9 has a fragment of 834 bp and has 60% identity with the PISTILATA from Arabidopsis.The deduced amino acid sequence of PhPI9 had the typical PI-motif.It also formed a subelade with other monoeot PI-type genes in phylogenetie analysis.Southern analysis showed that PhPI9 was present in the Phalaenopsis orchid genome as a single copy.Furthermore,it was expressed only in the lip of the Phalaenopsis flower and no expression was detected in vegetative organs.Thus,as a B-function MADS-box gone,PhP19 specifies floral organ identity in orchids.     

Arabidopsis SKP1, a homologue of a cell cycle regulator gene, is predominantly expressed in meristematic cells

The yeast SKP1 gene and its human homolog p19 ^skp1 encode a kinetochore protein required for cell cycle progression at both the DNA synthesis and mitosis phases of the cell cycle. In orchids we identified a cDNA (O108) that is expressed in early stages of ovule development and is homologous to the yeast SKP1. Based on the orchid O108 cDNA clone, we identified and characterized an Arabidopsis thaliana (L.) Heynh. cDNA designated ATskp1 that also has high sequence similarity to yeast SKP1. The Arabidopsis ATskp1 is a single-copy gene that mapped to chromosome 1. The expression of the ATskp1 gene was highly correlated with meristem activity in that its mRNA accumulated in all of the plant meristems including the vegetative shoot meristem, inflorescence and floral meristems, root meristem, and in the leaf and floral organ primordia. In addition, ATskp1 was also highly expressed in the dividing cells of the developing embryo, and in other cells that become multinucleate or undergo endoreplication events such as the endosperm free nuclei, the tapetum and the endothelium. Based on its spatial pattern of expression, ATskp1 is a marker for cells undergoing division and may be required for meristem activity. Received: 6 June 1997 / Accepted: 2 July 1997     

Studies on somaclonal variation in Phalaenopsis

The morphological and genetic variations in somaclones of Phalaenopsis True Lady “B79-19” derived from tissue culture were evaluated. In 1360 flowering somaclones, no apparent difference was found in the shape of the leaves, whereas flowers in some somaclones were deformed. We have demonstrated that 38 selected random primers can be used to generate amplified segments of genomic DNA and to differentiate polymorphisms of somaclonal variations in Phalaenopsis. The random amplified polymorphic DNA (RAPD) data indicated that normal and variant somaclones are not genetically identical. We also studied the banding patterns of aspartate aminotransferase (AAT) and phosphoglucomutase (PGM) in young leaves of variant and normal somaclones of Phalaenopsis. With respect to AAT, three distinct banding patterns were found in normal somaclones and only two-banded phenotypes were detected in variant somaclones. In a comparison of the banding patterns of PGM isozymes, three to four bands were detected in normal somaclones and two to three bands in variant ones. Received: 15 August 1997 / Revision received: 16 February 1998 / Accepted: 1 May 1998     

Expression of a chitinase transgene in rose (Rosa hybrida L.) reduces development of blackspot disease (Diplocarpon rosae Wolf)

Blackspot, caused by the Ascomycete fungus Diplocarpon rosae, is the most widespread and pernicious disease of cultivated roses. While some species of rose possess resistance to D. rosae, none of the modern-day rose cultivars are fully resistant to the pathogen. In the current study, Biolistic gene delivery was used to introduce a rice gene, encoding a basic (Class I), chitinase into embryogenic callus of the blackspot-susceptible rose (Rosa hybrida L.) cv. Glad Tidings. The plasmid used for transformation carried the neomycin phosphotransferase (nptII) gene facilitating the selection and regeneration of transgenic plants on medium containing 250 mg/l kanamycin. Southern analysis confirmed integration of 2–6 copies of the chitinase gene into the rose genome; gene expression was confirmed by enzyme assay. Bioassays demonstrated that expression of the chitinase transgene reduced the severity of blackspot development by 13–43%. This degree of resistance to the pathogen correlated with the level of chitinase expression in the transgenic rose plants. The introduction of disease defence genes into rose provides a method of producing blackspot-resistant rose cultivars sought by breeders and growers.     

中国兰科蝴蝶兰属一新记录种——洛氏蝴蝶兰

报道了中国兰科Orchidaceae植物一新记录种——洛氏蝴蝶兰Phalaenopsis lobbii (Rchb. f.) H. R. Sweet.。它与P. gibbosa、P. parishii非常相似, 但本种的花白色, 不具"Z"字形花序轴, 可以区别于前者; 唇瓣上两侧裂片之间的横向半圆形附属物边缘具不规则细锯齿可以区别于后者。