鱼腥草茎叶解剖学特征及其与其他古草本类群相关结构的比较分析

采用常规石蜡切片法．对鱼腥草的药用部位地上茎、根状茎和叶进行了解剖学观察。鱼腥草茎和叶的表皮下有特殊的皮下层细胞．茎的皮层和髓中有分泌细胞存在。地上茎和根状茎之间在皮层细胞层数、周维纤维柱的有无、维管柱和髓所占比例、维管束束数、次生生长等办面存在差异,这些差异与它们各自担负的生理功能相关联。叶的皮下层细胞显著,它们是复表皮的一部分。叶表皮上有胶质化表皮细胞和水钵的结构。对鱼腥草茎和叶中的皮下层细胞的来源和功能、与其他古草本类群相关的结构特征以及水钵的结构与分铂等问题进行了探讨。     

Mepiquat chloride seed treatment and germination temperature effects on cotton growth,nutrient partitioning,and water use efficiency

Cotton seed (Gossypium hirsutum L. cv. “Stoneville 825”), treated with 0, 0.2, 1.0, and 2.0 g active ingredient (a.i.) mepiquat chloride (MC) kg^?1, was evaluated for the effect of MC on early plant growth. Emergence rate and total emergence of MC-treated seed and control were similar regardless of germination temperature. However, the number of leaves and squares and the dry weight of leaves, stems, and roots for hydroponically grown cotton plants were significantly lower at lower germination temperatures (15°C for 3 day/30°C for 1 day and 15°C for 4 days) than at higher germination temperatures (30°C for 4 days and 30°C for 3 days/15°C for 1 day). All MC treatments significantly decreased the number of nodes, leaves, and squares, as well as dry weight of leaves, stems, and roots, as compared to control plants at 28 days after emergence. MC seed treatments also significantly reduced plant height and total leaf area compared to controls. Water-use efficiency (WUE) was significantly lower for the 1.0 g a.i. MC treatment than for control plants. In general, the highest rate of MC seed treatment resulted in greater concentrations of calcium, phosphorus, and nitrogen in plant leaves and stems and also in greater concentrations of magnesium, phosphorus, and nitrogen in roots than in controls.     

大蒜不同品种蒜薹发育的解剖学研究

通过形态观测和石蜡切片法,比较了2个大蒜品种的蒜薹发育和解剖结构。结果表明：（1）“陇县火蒜”比“改良蒜”蒜薹的表皮细胞形状规则,排列致密;角质层较薄;（2）“陇县火蒜”比“改良蒜”蒜薹表面的气孔数量少,但开张度大;分泌细胞出现早、体积大、数量多;维管束数量少、直径小;（3）“陇县火蒜”蒜薹髓细胞卫多边形,髓细胞间隙率小,而“改良蒜”蒜薹的髓细胞呈椭圆形,髓细胞间隙率大。     

Cellular events during interfascicular cambium ontogenesis in inflorescence stems of Arabidopsis

Development of cambium and its activity is important for our knowledge of the mechanism of secondary growth. Arabidopsis thaliana emerges as a good model plant for such a kind of study. Thus, this paper reports on cellular events taking place in the interfascicular regions of inflorescence stems of A. thaliana, leading to the development of interfascicular cambium from differentiated interfascicular parenchyma cells (IPC). These events are as follows: appearance of auxin accumulation, PIN1 gene expression, polar PIN1 protein localization in the basal plasma membrane and periclinal divisions. Distribution of auxin was observed to be higher in differentiating into cambium parenchyma cells compared to cells within the pith and cortex. Expression of PIN1 in IPC was always preceded by auxin accumulation. Basal localization of PIN1 was already established in the cells prior to their periclinal division. These cellular events initiated within parenchyma cells adjacent to the vascular bundles and successively extended from that point towards the middle region of the interfascicular area, located between neighboring vascular bundles. The final consequence of which was the closure of the cambial ring within the stem. Changes in the chemical composition of IPC walls were also detected and included changes of pectic epitopes, xyloglucans (XG) and extensins rich in hydroxyproline (HRGPs). In summary, results presented in this paper describe interfascicular cambium ontogenesis in terms of successive cellular events in the interfascicular regions of inflorescence stems of Arabidopsis.     

Some properties of pea cholinesterase and its activity in plant parts at different growth stages

Cholinesterase activity was studied in 2 to 10-week-old pea plants cultivated under artificial illumination. Free and membrane-bound forms of the enzyme were separated by extracting the enzyme from pea shoots with buffers differing in ionic strength. The ratio of the free cholinesterase to the membrane-bound one fluctuated between 1 : 1 and 1 : 2.5. The free cholinesterase was inhibited by neostigmine (0.1mmoll^-1) by 50%, the membrane-bound enzyme by 90%. The pH optimum of cholinesterase activity was 8.5, the temperature optimum 37 °C. The enzyme activity was increased by some cations in this order: Mg²⁺ < < K⁺. The K^m value for the substrate S-acetylthiocholine iodide was 250 μmoll^-1, the enzyme activity being inhibited by concentrations higher than 3 mmoll^-1 of this substrate. The activity of the membrane-bound enzyme was demonstrated in the roots, leaves, stems, fruits, seeds and carpels, but could not be reliably detected in the blossoms. The highest activity expressed per fresh matter was found in older leaves and in the fruits, the lowest in the roots and stems. Cholinesterase activity in plant parts markedly varied during the investigated growth period.     

Occurrence of the plant growth regulator jasmonic acid in plants

The natural occurrence of jasmonic acid and its methyl ester in plants has been studied using different methods such as GC, GC-MS, HPLC, radioimmunoassay, and bioassay. Jasmonic acid was detected in several Leguminosae plants and a number of species belonging to nine other Angiospermae families. Highest amounts occurred in fruit parts, especially the immature pericarp, but it was found also in flowers and vegetative plant parts, e.g. leaves, stems, and germs. Young apple fruits contain both jasmonic acid and methyl jasmonate, and in Douglas fir, the only Gymnospermae species studied, only the methyl ester could be detected. Jasmonic acid is discussed as an endogenous plant growth regulator widely distributed in higher plants.     

Cellular sequestration of cadmium in the hyperaccumulator plant species Sedum alfredii

Spatial imaging of cadmium (Cd) in the hyperaccumulator Sedum alfredii was investigated in vivo by laser ablation inductively coupled plasma mass spectrometry and x-ray microfluorescence imaging. Preferential Cd accumulation in the pith and cortex was observed in stems of the Cd hyperaccumulating ecotype (HE), whereas Cd was restricted to the vascular bundles in its contrasting nonhyperaccumulating ecotype. Cd concentrations of up to 15,000 μg g(-1) were measured in the pith cells, which was many fold higher than the concentrations in the stem epidermis and vascular bundles in the HE plants. In the leaves of the HE, Cd was mainly localized to the mesophyll and vascular cells rather than the epidermis. The distribution pattern of Cd in both stems and leaves of the HE was very similar to calcium but not zinc, irrespective of Cd exposure levels. Extended x-ray absorption fine structure spectroscopy analysis showed that Cd in the stems and leaves of the HE was mainly associated with oxygen ligands, and a larger proportion (about 70% in leaves and 47% in stems) of Cd was bound with malic acid, which was the major organic acid in the shoots of the plants. These results indicate that a majority of Cd in HE accumulates in the parenchyma cells, especially in stems, and is likely associated with calcium pathways and bound with organic acid (malate), which is indicative of a critical role of vacuolar sequestration of Cd in the HE S. alfredii.     

Acetylcholine in plants: Presence,metabolism and mechanism of action

Acetylcholine (ACh) has been detected in representatives of many taxonomic groups throughout the plant kingdom. The site of its synthesis in plants is probably young leaves. In some plant species choline acetyltransferase (ChAT) activity has been found. This enzyme showing properties similar to animal ChAT, probably participates in ACh synthesis from its precursors, choline and acetyl-Coenzyme A. Acetylcholinesterase (AChE) activity has also been found in many plant tissues. This enzyme decomposes ACh and exhibits properties similar to animal AChE. The presence of both ChAT and AChE in plant tissues suggests that ACh undergoes similar metabolism in plants as it does in animals. Exogenous ACh affects phytochrome-controlled plant growth and development. Mimicking red light (R), ACh stimulates adhesion of root tips to a glass surface and influences leaf movement and membrane permeability to ions. It also affects seed germination and plant growth. Moreover, ACh can modify some enzyme activity and the course of some metabolic processes in plants. Acetylcholine in the presence of calcium ions (Ca²⁺), like R stimulates swelling of protoplast isolated from etiolated wheat leaves. It is proposed that the primary mechanism of action of ACh in plant cells is via the regulation of membrane permeability to protons (H⁺), potassium ions (K⁺), sodium ions (Na⁺) and Ca²⁺.     

菰适应湿地环境的解剖和屏障结构特征研究

菰(Zizania latifolia)是一种多年生挺水植物,为了探讨该植物根、茎和叶的解剖结构、组织化学及其质外体屏障的通透性生理。该文利用光学显微镜和荧光显微镜,对菰的根、茎、叶进行了解剖学和组织化学研究。结果表明:(1)菰不定根解剖结构由外而内分别为表皮、外皮层、单层细胞的厚壁机械组织层、皮层、内皮层和维管柱;茎结构由外而内分别为角质层、表皮、周缘厚壁机械组织层、皮层、具维管束的厚壁组织层和髓腔。叶鞘具有表皮和具维管束皮层,叶片具有表皮,叶肉和维管束。(2)不定根具有位于内侧的内皮层及其邻近栓质化细胞和外侧的外皮层组成的屏障结构;茎具内侧厚壁机械组织层,外侧的角质层和周缘厚壁机械组织层组成的屏障结构,屏障结构的细胞壁具凯氏带、木栓质和木质素沉积的组织化学特点,叶表面具有角质层。(3)菰通气组织包括根中通气组织,茎、叶皮层的通气组织和髓腔。(4)菰的屏障结构和解剖结构是其适应湿地环境的重要特征,但其茎周缘厚壁层和厚壁组织层较薄。由此推测,菰适应湿地环境,但在旱生环境中分布有一定的局限性。     

Effect of Growth Irradiance on Photosynthesis and Transpiration inPhaseolus vulgaris L.

In comparison with primary leaves of French bean plants grown under a photon flux density of 100 μeinstein m-2 s-1 (LP), leaves grown under 400 μeinstein m-2 s-1 (HP) were thicker (contained 82 to 104% more dry matter per blade area), had 44 to 48% higher stomatal frequency, 18 to 26% more chlorophyll (a + b) per leaf area unit and 31 to 42% less chlorophyll (a + b) per dry matter unit, 41% higher photosynthetic and 38% higher transpiration rates at light saturation, 33% higher stomatal conductance and 40% higher Photosystem 2 (H2O → K3[Fe(CN)6]) activity of isolated chloroplasts. There were no significant differences in the Photosystem 1 (TMPD/Ascorbate → MV) activity per unit amount of chlorophyll. Higher growth irradiance increased the ratio of frequencies of stomata in the upper/lower epidermes.     

Successful expression of a novel bacterial gene for pinoresinol reductase and its effect on lignan biosynthesis in transgenic Arabidopsis thaliana

Pinoresinol reductase and pinoresinol/lariciresinol reductase play important roles in an early step of lignan biosynthesis in plants. The activities of both enzymes have also been detected in bacteria. In this study, pinZ, which was first isolated as a gene for bacterial pinoresinol reductase, was constitutively expressed in Arabidopsis thaliana under the control of the cauliflower mosaic virus 35S promoter. Higher reductive activity toward pinoresinol was detected in the resultant transgenic plants but not in wild-type plant. Principal component analysis of data from untargeted metabolome analyses of stem, root, and leaf extracts of the wild-type and two independent transgenic lines indicate that pinZ expression caused dynamic metabolic changes in stems, but not in roots and leaves. The metabolome data also suggest that expression of pinZ influenced the metabolisms of lignan and glucosinolates but not so much of neolignans such as guaiacylglycerol-8-O-4′-feruloyl ethers. In-depth quantitative analysis by liquid chromatography–tandem mass spectrometry (LC-MS/MS) indicated that amounts of pinoresinol and its glucoside form were markedly reduced in the transgenic plant, whereas the amounts of glucoside form of secoisolariciresinol in transgenic roots, leaves, and stems increased. The detected levels of lariciresinol in the transgenic plant following β-glucosidase treatment also tended to be higher than those in the wild-type plant. Our findings indicate that overexpression of pinZ induces change in lignan compositions and has a major effect not only on lignan biosynthesis but also on biosynthesis of other primary and secondary metabolites.     

Nitrate-reductase expression is under the control of a circadian rhythm and is light inducible in Nicotiana tabacum leaves

Over a 24-h light-dark cycle, the level of mRNA coding for nitrate reductase (NR; EC 1.6.6.1) in the leaves of nitrate-fed Nicotiana tabacum L. plants increased throughout the night and then decreased until it was undetectable during the day. The amount of NR protein and NR activity were two-fold higher during the day than at night. When plants were transferred to continuous light conditions for 32 h, similar variations in NR gene expression, as judged by the above three parameters, still took place in leaf tissues. On the other hand, when plants were transferred to continuous dark conditions for 32 h, the NR-mRNA level continued to display the rhythmic fluctuations, while the amount of NR protein and NR activity decreased constantly, becoming very low, and showed no rhythmic variations. After 56 h of continuous darkness, the levels of NR mRNA, protein and activity in leaves all became negligible, and light reinduced them rapidly. These results indicate the circadian rhythmicity and light dependence of NR expression.     

Carbon isotopic composition of legumes with photosynthetic stems from mediterranean and desert habitats

The carbon isotopic compositions of leaves and stems of woody legumes growing in coastal mediterranean and inland desert sites in California were compared. The overall goal was to determine what factors were most associated with the carbon isotope composition of photosynthetic stems in these habitats. The carbon isotope signature (d13C) of photosynthetic stems was less negative than that of leaves on the same plants by an average of 1.51 ± 0.42 ;pp. The d13C of bark (cortical chlorenchyma and epidermis) was more negative than that of wood (vascular tissue and pith) from the same plant for all species studied on all dates. Desert woody legumes had a higher d13C (less negative) and a lower intercellular CO2 concentration (Ci ) (for both photosynthetic tissues) than that of woody legumes from mediterranean climate sites. Differences in the d13C of stems among sites could be entirely accounted for by differences among site air temperatures. Thus, the d13C composition of stems did not indicate a difference in whole-plant integrated water use efficiency (WUE) among sites. In contrast, stems on all plants had a lower stem Ci and a higher d13C than leaves on the same plant, indicating that photosynthetic stems improve long-term, whole-plant water use efficiency in a diversity of species.     

Hawaiian ethnobotanical studies I. native food and beverage plants

Cultivated food plant stocks were brought to Hawaii by the immigrating Polynesians and composed most of their basic diet. Extensive use, however, was made of the highly endemic (95%' for flowering plants and 67% for ferns) flora. The Hawaiian was both a proficient agriculturist and naturalist. Nearly all of the vascular plant genera were given vernacular names, as well as many species and varieties. Twenty-five genera and over 85 species of vascular plants were used as food sources. These included fern auricles,pith, young fronds, and rhizomes; flowering plant roots (both aerial and underground), tubers, stems, young plants, young shoots, leaves, male flower bracts, fruits, and seeds. Six genera and 55 species of vascular plants were prepared for beverage purposes. These plants are listed in a table, with the following information provided: family, scientific name, common names, species distribution (island, altitude, occurrence, and habit), and plant part utilized. Lists of vernacular names and plant part sources are also included. Succeeding papers will cover other aspects (introduced food and beverage plants, and native and introduced plants used for ceremonies, cultural artifacts, decorations, dye, fiber, etc.).     

The effect of simultaneous short term action of streptomycin and humate on plants

Humate (10 mg l^?1) supplemented to streptomycin solutions (0.1 and 1 mM) stimulates growth of germinating wheat and barley grains and of apical cuttings ofCrassula portulacea after 24 h treatment. It does not, however, prevent formation of albinic leaves. Albinism induced by the streptomycin alone and by streptomycin in presence of humate is irreversible and can be removed neither by an iron salt nor by a chelate added to the nutrition solution or applied on the leaves. Cells of plants treated with streptomycin and humate are larger than those of plants treated with the streptomycin alone. The same is true for plastids which in both cases are colourless and much smaller than chloroplasts of control plants. These plastids in a living or a fixed state have reduced ability to uptake stains. The albinic leaves are anatomically similar to chlorotic leaves of virus infected plants.     

Determination of the cytokinin complement in healthy and witchesbroom malformed proteas

Cytokinins from normal and witchesbroom malformed stems of proteas were determined by radioimmunoassay following sample resolution by high-performance liquid chromatography (HPLC). Material from the early stages of shoot malformation had increased cytokinin concentrations which, over time, declined to the concentrations found in normal-growing stems. The cytokinin complement of the malformed structures was different from that of normal stems. The high concentrations of isopentenyladenosine detected appear to be related to the loss of the correlative inhibition of lateral buds and the development of the witchesbroom structures and may result from localized changes in cytokinin biosynthesis and/or metabolism.     

Lead phytoavailability change driven by its speciation transformation after the addition of tea polyphenols (TPs): Combined selective sequential extraction (SSE) and XANES analysis

Background and aims

Metal species in rhizosphere soil profoundly influence their mobility and phytoavailability. Clarifying the speciation transformation of heavy metals helps understand their translocation and accumulation in plants.

Methods

Single extraction, selective sequential extraction (SSE) and X-ray absorption near-edge structure (XANES) spectroscopy were employed to investigate the speciation transformation of lead (Pb) and its influence on metal accumulation in tea plants after the addition of tea polyphenols (TPs).

Results

Pb content was decreased in young leaves and stems, whereas increased in roots, after TPs were amended to soil. Both SSE and XANES analysis suggested bioavailable Pb was transformed to organically bound Pb after the addition of TPs. The increased percentage of organically bound Pb might be fixed in the cell wall of plant root through a ternary complex formed between the Pb-organic matter complex and cell wall components. Therefore, Pb translocation from roots to young tissues was decreased.

Conclusions

Pb phytoavailability change was driven by its speciation transformation after the addition of TPs. Combined SSE and XANES spectroscopy represent powerful tools to study metal speciation transformation in plant and soil systems.     

Electrophoretic investigation of ribonuclease in roots and leaves ofVicia faba L.

Isozyme patterns and specific activity of ribonuclease (ribonucleate pyridinenucleotido-2′-transferase, E. C. 2.7.7.16) were followed in the extracts of segments from three growth zones of the root and in extracts of young and senescent leaves ofVicia faba L. Electrophoreograms of extracts from all three investigated root zones were identical, in the electrophoreograms of extracts from senescent leaves however one new ribonuclease occurred which could not be detected in the electrophoreograms of extracts from young leaves. Extracts from senescent leaves had higher specific activity of ribonuclease than extracts from young leaves. Extracts from the enlargement zone of the root and those from the maturation zone had a three times higher specific activity of RNase than extracts from the division zone.     

Growth and infectivity of callus cultures of tomato plants infected with a mycoplasma disease — Potato witches' broom

Callus tissues were derived from the stem of healthy tomato plants (Lycopersicum esculentum Mill. ev. Pr?honické) and of plants infected with potato witches' broom—a disease caused by mycoplasma. Callus cultures were established on modified fully synthetic media described byMorel (1948) and byMurashige andSkoog (1962). Callus cultures obtained from diseased plants were grown and subcultured on both media, growth in primary isolates from healthy plants took place on the Murashige and Skoog medium only. Growth of callus tissue derived from diseased plants was more vigorous even after several subcultivations in comparison with callus tissues isolated from healthy plants. Variations in the morphology in these callus cultures were not noted. Callus cells of diseased plants varied in size; they were about 50% larger than those from healthy ones. Implantation of primary and subcultivated callus tissues into tomato stems of healthy plants did not show any symptoms of infection on test plants.