The prevention of dehydration injury in celery seeds by polyethylene glycol, abscisic acid, dark and high temperature

Celery seeds ( Apium graveolens L.) given a germination induction period (3 days imbibition at 17°C in the light) could be prevented from germinating by up to 14 days subsequent exposure to high temperature (32°C), polyethylene glycol (PEG), abscisic acid (ABA) or dark (22°C). When the seeds were returned to 17°C in the light, germination occurred and, except for the high temperature treatment, was more rapid compared to seeds given a germination induction period only.
Celery seeds incubated for 3 days at 17°C in the light and then air-dried at 20°C germinated slowly when re-sown at 17°C in the light, and achieved only 19% germination after 21 days. Exposing the seeds to high temperature, PEG, ABA or dark for up to 14 days before drying maintained seed viability and subsequent germination was faster. The longer treatment periods gave increased benefit, and PEG was the most effective treatment. It is suggested that the effectiveness of the treatments in inducing dehydration tolerance relates to their ability to inhibit germination possibly via their prevention of cell expansion.     

Phosphatidylcholine biosynthesis in celery cell suspension cultures with altered sterol compositions

Cell suspension cultures of celery were treated with the plant growth regulator, paclobutrazol. Lipid analysis revealed that use of this xenobiotic had little effect on the quantity or acyl quality of the major phospholipid classes or on the actual amounts of free sterol present in the cell. It did however, cause dramatic changes in the free sterol profile exhibited by treated cultures. In this respect, an increase in 14α-methylsterols was observed.
The synthesis of phosphatidylcholine in celery cell suspension cultures with altered free sterol compositions was studied using two radiolabelled biosynthetic precursors, [³H-methyl]choline and [³H-methyl]methionine. The studies showed that the rate of phosphatidylcholine biosynthesis via the CDP-base pathway proceeded at a slower rate in paclobutrazol treated cultures. Accumulation of label phosphocholine was observed arising from reduced CTP:cholinephosphatecytidylyltransferase activity. In contrast, phosphatidylcholine biosynthesis via the sequential methylation of ethanolamine derivatives appeared to be enhanced in cells that had an unusually high 14α-methylsterol content. From these investigations it may be postulated that the biosynthesis of phosphatidylcholine in Apium graveolens suspension cultures may be regulated by membrane sterol composition.     

dbEST‐derived microsatellite markers in celery (Apium graveolens L. var. dulce)

We report on the development of 11 (from database expressed sequence tags) dbEST‐derived microsatellite markers in celery (Apium graveolens L. var. dulce). The sequences were obtained from DNA accessions available from GenBank and contained di‐, tri‐ and pentanucleotidic motifs. All the microsatellites were found in expressed sequence tags and they are expected to become useful tools for ecological, genetic and evolutionary studies, as well as for celery breeding. Polymorphism was explored in 16 celery commercial varieties, and marker transferability was tested on three accessions of celeriac (A. graveolens var. rapaceum). Primers and PCR conditions for microsatellite amplification are reported.     

SC-CO2和乙酸乙酯萃取芸香中活性成分的比较分析

为了探讨超临界二氧化碳(supercritical carbon dioxide, SC-CO2)技术与提取物的分级分离在萃取芸香活性成分的应用价值,本研究采用SC-CO2和乙酸乙酯萃取芸香中植物蜡和活性成分,并调查粒径和CO2流量对提取产量的影响。在250 bar、40℃条件下提取,并使第一个分离器冷却到-10℃,可获得较好的提取效率。当粒径较小时,提取过程更快,即内部传质控制该过程。分级分离可选择性去除表皮植物蜡,约占由SC-CO2处理产生的总提取物的77.5%W/W。第二分离器中的获得的提取物中活性化合物可达86.3%W/W。随后采用气相色谱-质谱联用仪(gas chromatography-mass spectrometry, GC-MS)分析表明,乙酸乙酯提取物低于SC-CO2提取物的萃取效率,主要是由于提取物中含有大量的植物蜡。本研究为超临界二氧化碳技术在萃取芸香活性成分方面的提供技术参考。     

芸香地上器官的生物学研究

对芸香的茎、叶及花等器官的形态结构进行了较为系统的观察研究,对花芽形成及开花过程进行了客观描述.芸香花有顶生和侧生两种,柱头为"湿柱头",叶片具有典型旱生型植物特点,茎叶中均含有簇晶和油腔,这些特征可作为分类学上鉴别该物种的性状.茎的淀粉积累过程:花前期淀粉积累很少(6月下旬),10月下旬达高峰,之后略有减少并保持稳定直至被冻死.对此结合当地温度及水分条件进行了抗寒、抗旱的讨论.     

Effects of Ruta graveolens leaves on soil characteristics and on seed germination and early seedling growth of four crop species

Effects of rue (Ruta graveolens) leaves on soil characteristics and on germination and seedling growth of four crop species (radish, zucchini, cauliflower and tomato) were investigated. Soil not previously associated with rue was mulched and amended with its fresh leaves. The objectives of the present study were to determine: (i) the changes in soil chemical characteristics after addition of rue leaves, (ii) the growth responses in soils treated with R. graveolens leaves, and (iii) whether the soil chemistry changes affect plant growth. Results indicate that soil incorporated with rue leaves had higher values of water‐soluble phenolics, electrical conductivity and nitrate, and lower pH values compared to untreated soil. Seed germination of radish and tomato was suppressed in covered and amended soils compared to control soil. Seedling development for all the species was suppressed in incorporated and amended soil, compared to the rue‐free soil. Correlations between soil chemical characteristics, germination and seedling growth of plants are also discussed.     

Ultraviolet-B radiation effects on the Mediterranean ruderal Dittrichia viscosa

Young seedlings of Dittrichia viscosa L. (syn. Inula viscosa (L.) Aiton) (Asteraceae) were extensively treated with artificial rain in order to remove the water soluble component of their epicuticular UV-B absorbing compounds. As a result, 75% of the epicuticular absorbing capacity at 300 nm was lost. The seedlings were subsequently grown in a naturaly lit glasshouse for 80 days under 0.06, 6.41 and 10.14 kJ m^-2 day ^-1 biologicaly effective UV-B radiation doses. The initial, pre-rain values of the water soluble, epicuticular UV-B absorbing potential was restored in about three weeks. During this transient period the plants were exposed to the enhanced UV-B radiation doses with part of their UV-B radiation screen removed. Although a trend for increased accumulation of epicuticular UV-B absorbing capacity was observed with increasing UV-B radiation doses, the allelopathic potential of the epicuticular material remained unchanged. Internal (cellular) UV-B absorbing compounds and chlorophylls were unaffected, but total carotenoids were increased, indicating a possible protective role against UV-B radiation damage. Leaf, stem and root dry mass were the same under all treatments but UV-B radiation caused a reduction in the dry mass invested per unit leaf area with a concomitant increase in leaf area. The importance of this UV-B radiation induced selective allocation of photosynthate to the production of assimilative surfaces is discussed.     

Studies of Technical Conditions of Somatic Embryogenesis in Cell Suspension Culture of Apium Graveolens

Using hypocotyls (5~10 mm) of Apium graveolens L. as explant, calli were induced in induction medium (MS + 1.0 mg/L 2, 4-D). The embryogenic calli were transformed to differentiation medium (MS+0. 5 mg/L kinetin+ 500 mg/L CH+500 mg/L Prolin) after several subsequent subcultures and selection by replacement of solid and liquid medium. Technical conditions such as the shake rate of the flask, the initial cell density, as well as subsequent the initial pH values during culture were under consideration. With the optimum flask shake rate of about 100~150 r/min, initial cell density of 2.0% (fresh weight) and the initial pH value of 5.5, the authors have obtained 130 normal cotyledon embryos in each mL of cultures.     

Isolation of the major chiral compounds from Bubonium graveolens essential oil by HPLC and absolute configuration determination by VCD

The chirality issues in the essential oils (EOs) of leaves and flowers from Bubonium graveolens were addressed by chiral high‐performance liquid chromatography (HPLC) with polarimetric detection and vibrational circular dichroism (VCD). The chemical compositions of the crude oils of three samples were established by gas chromatography / mass spectrometry (GC/MS). The well‐known cis ‐chrysanthenyl acetate ( 1 ), oxocyclonerolidol ( 2 ), and the recently disclosed cis ‐acetyloxychrysanthenyl acetate ( 3 ), the three major chiral compounds, were isolated by preparative HPLC. The naturally occurring oxocycloneroledol ( 2 ), mostly found in the leaf oil (49.4–55.6%), presents a (+) sign in the mobile phase during HPLC on a chiral stationary phase (CSP) with a Jasco polarimetric detection. The naturally occurring cis ‐chrysanthenyl acetate ( 1 ) and cis ‐acetyloxychrysanthenyl acetate ( 3 ), mostly found in the flower EO (35.9–74.9% and 10.0–34.3%, respectively), both present a (−) sign. HPLC on a CSP with polarimetric detection is an unprecedented approach to readily differentiate the flower and leaf EOs according to their chiral signature. The comparison of the experimental and calculated VCD spectra of pure isolated 1 , 2, and 3 provided their absolute configuration as being (1S ,5R ,6S )‐(−)‐2,7,7‐trimethylbicyclo[3.1.1]hept‐2‐en‐6‐yl acetate 1 , (2R ,6R )‐(+)‐6‐ethenyl‐2,6‐dimethyl‐2‐(4‐methylpent‐3‐en‐1‐yl)dihydro‐2H‐pyran‐3(4H)‐one) 2 and (1S ,5R ,6R ,7S )‐(−)‐7‐(acetyloxy)‐2,6‐dimethylbicyclo[3.1.1]hept‐2‐en‐6‐yl]methyl acetate 3 . Compounds 1 , 2, and 3 were already known in B. graveolens but this is the first report of the absolute configuration of (+)‐ 2 and (−)‐ 3 . The VCD chiral signatures of the crude oils were also recorded.     

A phytogeochemical survey of the flora of ultramafic and adjacent normal soils in North Morocco

Variation in plant elemental composition (Ni, Ca, Mg, Mg/Ca ratio) in relation to soil composition was investigated in a poorly studied ultramafic area in the north of Morocco. A total of 142 leaf samples representing 36 species from 9 sites (5 ultramafic and 4 normal soils from adjacent areas) were analysed. The soil was richer in Mg and Ni and had a higher Mg/Ca ratio in the ultramafic sites than in the control sites, and these differences were qualitatively reflected in the average mineral composition of the plants. However, there were considerable differences in mineral composition among species within serpentinic sites, indicating that species with contrasting mineral nutrition strategies can cope with the mineral element imbalance characteristic of ultramafic soils. Particularly noteworthy was the finding that species with high requirements of Ca are not excluded from serpentinic soils. In view of their high responsiveness to soil nickel and magnesium concentration, Dittrichia viscosa and Lavandula dentata are proposed as bioindicators of these elements in the soil in the Rif area. By contrast, two local serpentine endemics, Halimium atriplicifolium and Notholaena marantae were excluders of nickel and magnesium. This revised version was published online in August 2006 with corrections to the Cover Date.