Physiological responses to salt stress in young umbu plants

Soil salinity affects plant growth and development due to harmful ion effects and water stress caused by reduced osmotic potential in the soil solution. In order to evaluate the effects of salt stress in young umbu plants, research was performed in green house conditions at the Laboratory of Plant Physiology at Federal Rural University of Pernambuco, Brazil. Growth, stomatal behaviour, water relations, and both inorganic and organic solutes were studied aiming for a better understanding of the responses of umbu plants to increasing salinity. Plants were grown in washed sand with Hoagland and Arnon nutrient solution with 0, 25, 50, 75, and 100 mM NaCl. Growth, leaf water potential, transpiration, and diffusive resistance were evaluated. Na⁺, K⁺, Cl⁻, soluble carbohydrates, and free amino acid contents were measured in several plant organs. Most variables were affected with salinity above 50 mM NaCl showing decreases in: number of leaves, plant height, stems diameter, and dry masses, and increases in root-to-shoot ratio. Reductions in ψ_pd were observed in plants grown under 75 and 100 mM NaCl. All salt levels above zero increased Na⁺ and Cl⁻ contents in leaves. However, K⁺ content was not affected. Na⁺ and Cl⁻ in stems and roots reached saturation in treatments above 50 mM NaCl. Organic solute accumulation in response to salt stress was not observed in umbu plants. These results suggest that umbu plants tolerate salt levels up to 50 mM NaCl without showing significant physio-morphological alterations.     

Seed Dispersal by Salvin's Curassow,Mitu salvini (Cracidae), in a Tropical Forest of Colombia: Direct Measurements of Dispersal Distance1

Seed dispersal by Salvin's curassows (Mitu salvini) was studied in a lowland tropical forest at La Macarena on the border of the Macarena and Tinigua National Parks, the Department of Meta, Colombia. Continuous observations were made on the feeding and ranging behavior of a well-habituated pair of birds from 0600 to 1800 h for 19 days. Ibtal observation time was 222 h. The daily distance traveled by the birds ranged from 630 to 3750 m, with a mean of 1959 m (± 776 m). The total home range was ca 34.4 ha. Although curassows were observed consuming fruits of 13 species belonging to the families Rubiaceae, Meliaceae, Moraceae, Burseraceae, Leguminosae, and Lecythidaceae, only seeds of Geophila re fens (Rubiaceae) and Picas spbenophylla (Moraceae) were found in their feces. For G. repens, the mean and maximum retention times were 1 h 52 min (± 1 h 20 min) and 6 h 08 min, and the mean and maximum direct dispersal distances were 245 m (± 164 m) and 633 m. More than half the seeds were dispersed in canopy gaps. For F. sphenophylla, the mean and maximum retention times were 3 h 1 5 mm (± .37 min) and 7 h 08 min, and the mean and maximum direct dispersal distances were 329 m (± 46 m) and 451 m. Nearly 60 percent of the estimated seed intake of G. repens and 92-94 percent of F. sphenophylla were digested or damaged. The retention times and the dispersal distances for Streptogyna americana, which has adhesive burrs, were also measured. The mean and maximum retention times were 1 h 55 min (± 1 h 56 min) and 9 h 11 min, and the mean and maximum direct dispersal distances were 128 m (± 68 m) and 280 m. This is the first study in which direct measurements were made for retention times and dispersal distances of the epizoochory and endozoochory for birds in the field.     

Morphological and chemical variation of Stemona tuberosa from southern China – Evidence for heterogeneity of this medicinal plant species

• The occurrence of bioactive alkaloids and tocopherols was studied in 15 different provenances of Stemona tuberosa Lour. collected in southern China, to examine chemical variation of individuals that show notable differences in flower characteristics. Morphological variations stimulated examination of chemical characteristics of these individuals.
• Methanolic root extracts of 15 individuals of S. tuberosa were comparatively assessed with HPLC‐UV‐DAD/ELSD. Five of seven compounds were co‐chromatographically identified. Two compounds were isolated and their structure elucidated using NMR and MS. Amounts of alkaloids and tocopherols were determined using HPLC‐UV‐DAD/ELSD with the external standard method.
• Five alkaloids, tuberostemonine ( 1 ), tuberostemonine A ( 2 ), neotuberostemonine ( 3 ), tuberostemonine N ( 4 ), stemoninine ( 5 ) and two 3,4‐dehydrotocopherol derivatives were identified. Within S. tuberosa alkaloid accumulation tends either towards tuberostemonine ( 1 ) or stemoninine ( 5 ). All individuals show a notable co‐occurrence of compounds 1 or 5 and 3,4‐dehydro‐δ‐tocopherol ( 6 ). These results coincide with differences in flower morphology of S. tuberosa.
• Stemona tuberosa, as defined in the Flora of China, shows a remarkable variation in flower morphology and additionally in the accumulation of alkaloids. The obtained data show the need for future species delimitation to either species or subspecies level.

     

荸荠营养器官的发育与解剖学研究

荸荠同化茎起源于肉质主茎倒２或倒３叶的叶腋内。同化茎基部着生二鞘状叶,鞘状叶对早期同化茎穿出土面具保护作用。匍匐茎大多起源于同化茎基部鞘状叶的叶腋内。当植株开始抽生花茎时,地下匍匐茎顶端开始膨大。球茎的膨大是匍匐茎顶端５－６节的基本组织经细胞有丝分裂,增加细胞数目,然后由细胞体积的扩大来实现的。球茎具足够的营养物质供来年顶芽萌发的需要,故属水生植物冬芽的性质。     

Scale up production of isoflavonoids in cell suspension cultures of Pueraria tuberosa grown in shake flasks and bioreactor

Cell cultures of Pueraria tuberosa were grown in vessels of different sizes and 2L stirred tank bioreactor containing modified MS medium with morphactin (0.1 mg l^?1) and 2iP (5.0 mg l^?1) and 20% inoculum. Stable growth and total isoflavonoid yield of 76.6 mg l^?1 were recorded in the cultures during scale up. This was in concordance with the persistent yield of the individual isoflavonoids regardless of the vessel size.     

Expression of stylar incompatibility in the Andean clonal tuber crop oca (Oxalis tuberosa Mol., Oxalidaceae)

Long-, mid-, and short-styled clonal accessions of oca (Oxalis tuberosa) were intercrossed in a complete diallelic design. Pollen tube growth in styles was monitored in all diallelic crosses. Pollen fertility was estimated by two tests: staining of pollen grains with aceto-carmine and detection of β-galactosidase activity by the substrate X-Gal. The two methods of pollen fertility estimation were equally useful to detect fertility levels. Pollen originating from short stamens had the highest fertility (85%) and pollen from long stamens had the lowest fertility (70%). Pollen fertility was high throughout, but its degree varied with the stylar morph on which the pollen was formed. Long-styled accessions had the highest rates of fertile pollen. Differences in pollen fertility at different anther levels in the same style morph were also apparent. Pollen grain diameter of the six morph-anther level combinations was inversely correlated with pollen fertility. Pollen grains from long stamens were the largest and pollen grains from short stamens were the smallest. Neither pollen fertility nor pollen grain size had an influence on pollen tube growth in the style or on fruit and seed set. Pollen tubes growing within the styles were inhibited at a different level for each of the 18 cross combinations in the diallel. Although legitimate crosses had greatest pollen tube growth, some of the illegitimate inter- and intramorph crosses had equally high scores. Of all illegitimate crosses, mid-styled seed parents had the lowest level of stylar incompatibility. Fruit and seed set were highly correlated with the extent of pollen tube growth in the style. The number of pollen tubes entering ovules in a flower was in good agreement with the number of seeds produced per fruit. Therefore, it is concluded that stylar incompatibility is the major determinant of limited seed formation in oca even in the most successful legitimate cross combinations. Received: 1 September 1999 / Revision accepted: 4 April 2000     

A SUPEROXIDE DISMUTASE PURIFIED FROM THE ROOTS FROM Stemona tuberosa

Proteins from the fresh roots of Stemona tuberosa (Stemonaceae) were extracted into 20 mM phosphate buffer, pH 7.2/0.1 M NaCl, precipitated with 90% saturation ammonium sulfate, and enriched by diethylaminoethanol (DEAE) cellulose. The protein eluted as a single main peak from the unbound fractions (ST-1), and appeared as a single band with superoxide dismutase (SOD) activity after native polyacrylamide gel electrophoresis (PAGE) resolution and zymogram development. ST-1 was classified as SOD due to its strong inhibition by HCN and H₂O₂. The amino acid sequence of three tryptic peptides of ST-1 matched with the SOD isozymes from Ananas comosus and Solanum lycopersicum. The SOD consisted of at least two heterologous protein subunits with molecular mass of 17.6 and 31.5 kD, respectively, and had an optimal SOD activity at pH 5 and over a temperature range of 0–50°C. MgCl₂, MnCl₂, and HgCl₂ were strongly inhibitory at all concentrations tested. The SOD activity was completely negated in the presence of 0.5 mM SDS or 5 mM HgCl₂. The relationship between riboflavin and nitroblue tetrazolium (NBT) on SOD activity was linear, giving K _m and V _max values of the purified SOD of 62.414 ± 0.015 M and 101.010 ± 0.022 µmol/min/mg protein for NBT and 27.389 ± 0.032 M and 38.167 ± 0.021 µmol/min/mg protein for riboflavin, respectively.     

晚香玉引种及切花栽培

本文总结晚香玉引种与切花栽培技术.晚香玉在福建福州地区露地栽培,表现为适应性强、生长发育良好,基本无病虫害;切花瓶插寿命约15d;种球繁殖率6～10倍;种球经低温冷藏结合设施栽培,可周年开花.同时介绍了晚香玉不同栽培品种的开花特征.     

荸荠皮多糖体外清除自由基活性的研究

采用DPPH自由基法、邻苯三酚自氧化法和水杨酸法分别表征了荸荠皮多糖清除DPPH自由基(DPPH.)、超氧阴离子自由基(O2-.)和羟基自由基(.OH)的能力。结果显示,脱蛋白和未脱蛋白荸荠皮多糖具有清除自由基的活性,但该活性明显低于茶多酚。脱蛋白多糖清除DPPH.的能力高于未脱蛋白多糖,其清除50%DPPH.的作用质量浓度(EC50)分别为50.26 mg.L-1和76.22 mg.L-1。两种多糖清除.OH和O2-.的能力相当,其EC50(g.L-1)分别为0.118和0.124以及10.87和9.53。     

Wattled Curassows in Bolivia: abundance,habitat use,and conservation status

ABSTRACT The Wattled Curassow (Crax globulosa) is a globally threatened species restricted to humid várzea forest (seasonally flooded forest along white‐water rivers) in low‐lying regions of Amazonia. The Wattled Curassow were thought to have been extirpated from the Beni area of Bolivia, but were rediscovered near the Río Negro River in 2001. Our objectives were to determine the size of this population, examine habitat use, and based on our results, assess the conservation status of the Wattled Curassow. During July and August 2006, we used distance sampling to estimate the population density in our study area. We estimated the density of Wattled Curassows at 3.4 (95% CI: 1.4–8.1) individuals/km² and all were observed within 300 m of the river. Based on the availability of suitable habitat (18 km² of riparian várzea habitat within 300 m of the river), we estimated that the breeding population of Wattled Curassows in our study area consisted of 61 individuals. The specialized habitat requirements of the Wattled Curassow has important conservation implications because previous population estimates were based on the availability of várzea forest rather than the availability of water edge habitat within várzea forest. As a result, the current global population estimate (2500–9999) is higher than our estimate (500–2500) that takes the specialized habitat requirements of the Wattled Curassow into account. Given this low estimated population, along with the severely fragmented state of the few remaining populations and their dependence on a specialized and vulnerable habitat, we recommend that the status of the Wattled Curassow be upgraded from Vulnerable to Endangered.