Calcium,Calcium Oxalate Crystals,and Leaf Differentiation in the Common Bean (Phaseolus vulgaris L.)*

Young plants of Phaseolus vulgaris were grown in nutrient solutions at different levels of calcium concentration. When the calcium concentration was low more palisade parenchyma and less extended bundle sheath was formed at the adaxial side of minor veins of the leaves as compared to leaves of plants grown with higher calcium supply. The number of calcium oxalate crystals in the bundle sheath extensions was positively correlated to the amount of calcium fed to the plants. The ion induces additional cell divisions in the bundle sheath extensions. A high supply of calcium leads to the formation of a second type of crystal in the bundle sheath.     

Calcium oxalate crystals and crystal cells in the leaves ofRhynchosia caribaea (Leguminosae: Papilionoideae)

Summary The development and distribution of calcium oxalate crystals, stomates and hairs were studied in the first trifoliolate leaf ofRhynchosia caribaea (Leguminosae: Papilionoideae, Phaseoleae). Using light and transmission electron microscopy, the crystals were shown to occur in both bundle sheath and mesophyll cells. Crystal distribution and shapes are characteristic forRhynchosia. Crystals develop late in leaf development in contrast to the stomates and hairs. As these latter two structures decrease in number per unit area with leaf age, crystal number increases.     

Developmental features of calcium oxalate crystal sand deposition inBeta vulgaris L. Leaves

Summary Sugar beet (Beta vulgaris L.) leaf has a layer of cells extended laterally between the palisade parenchyma and spongy mesophyll that develop numerous small crystals (crystal sand) within their vacuoles. Solubility studies and histochemical staining indicate the crystals are calcium oxalate. The crystals are deposited within the vacuoles early during leaf development, and at maturity the cells are roughly spherical in shape and 2 to 3 times larger than other mesophyll cells. Crystal deposition is preceeded by formation of membrane vesicles within the vacuole. The membranes are synthesizedde novo in the vacuole and have a typical trilaminate structure as viewed with the TEM. The membranes are formed within paracrystalline aggregates of tubular particles (6–8nm outer diameter) as membrane sheets, but are later organized into chambers or vesicles. Calcium oxalate is then precipitated within the membrane chambers. The tubular particles involved in membrane synthesis are usually present in the vacuoles of mature crystal cells, but in very small amounts.     

福建冠豸山野生铁皮石斛的显微鉴定

对福建连城冠豸山开展野生铁皮石斛Dendrobium officinale实地调查,发现当地有铁皮石斛分布。对其茎、叶组织构造及茎的显微粉末特征等进行观察,结果表明,铁皮石斛茎维管束外侧的纤维群呈帽状,草酸钙针晶束于近表皮处多见,粉末中含针晶束的黏液细胞以及纤维束外具有含硅质块的细胞等特征可作为该药正确鉴别的依据。     

Primary Phloem Development in the Shoot Apex of Rhizophora mangle L. (Rhizophoraceae)

The primary phloem in the shoot apex of the mangrove Rhizophora mangle L. is largely confined to the comparatively condensed area between the first three leaf pairs. The main extension zone, surrounded by the stipular sheath of the third leaf pair, contains vascular bundles arranged in a procambial ring and characterized by a well-developed primary phloem and a less advanced xylem. The phloem consists of a great number of sieve elements, an equal number of associated companion cells, and a few phloem-parenchyma cells. The differentiation of the sieve-element protoplast (with e.g., chromatolytic nuclear degeneration, loss of the vacuole and most organelles) proceeds largely according to a well-known pattern. Their P-type plastids, however, form their protein crystals rather late and therefore cannot be used as an early cell marker. Lateral sieve-element walls are distinct from other wall parts and walls of other cells by their heavy nacreous thickenings, the formation of which is shown to be strictly correlated with the occurrence and orderly arrangement of cortical microtubules.     

芦荟叶内芦荟素细胞的发育和蒽醌类物质的积累

应用石蜡切片、半薄切片、组织化学和荧光显微镜观察相结合的方法研究了木立芦荟叶内芦荟素细胞的发生、发育以及其蒽醌类物质的积累过程。结果表明,在叶内原形成层束分化成维管束初期,原形成层束外侧的一层细胞发育成维管束鞘。原生韧皮部筛管产生时,其外方尚保留1—2层原形成层细胞,当后生韧皮部和木质部开始分化时,此层细胞分裂。在后生韧皮部和木质部发育成熟过程中,这些细胞体积逐渐增大,并液泡化,发育成为大型薄壁细胞(芦荟素细胞),位于筛管外侧。据此,芦荟叶维管束内的大型薄壁细胞的来源与韧皮部相同,属于特化的韧皮部薄壁组织细胞。用醋酸铅处理过的上述材料的切片观察表明,芦荟素细胞在细胞体积增大,并液泡化时,在液泡内出现蒽醌类物质沉淀物,在成熟细胞的大液泡中充满沉淀物,此时,在荧光显微镜下芦荟素细胞发出桔黄色荧光。可见,此种芦荟素细胞是芦荟叶内蒽醌类物质的主要储存场所。     

Centripetal Disposition of Bundle Sheath Chloroplasts During the Leaf Development of Eleusine coracana

Distribution of chloroplasts in bundle sheath cells was examinedby light and electron microscopy during the leaf developmentof finger millet (Eleusine coracana Gaertn.), an NAD malic enzymetype C₄ plant with centripetal arrangement of bundle sheathchloroplasts. Young chloroplasts are almost evenly distributedalong the cell walls in bundle sheath cells of folded immatureleaves. In elongating leaves and above the elongation zone thebundle sheath chloroplasts tend to lie along the radial wallsand the walls adjacent to the vascular bundle. They furthermigrate near to the vascular bundle and finally establish acentripetal arrangement. Mitochondria, microbodies and nucleusmigrate along with the chloroplasts. Etioplasts and other organellesare centripetally located in the bundle sheath cells of etiolatedseedlings grown in the dark. Bundle sheath chloroplast, C₄ plant, chloroplast, chloroplast orientation, Eleusine coracana, finger millet     

The "crystals" in the sugar beet (Beta vulgaris L.) leaves

Crystal containing cells widely distributed in plant tissues, though the origin of the crystals and their functions are still opened to question. Membrane vesicles in beet leaves are visible in electronic microscope. They originate in cytoplasm and penetrate into vacuole by pinocytosis with participation of tonoplast. In light microscope, vesicles are luminous likewise crystals in crystal cells. Such vesicles-"crystals" fulfill crystal cells also. The content of vesicles-"crystals" are electronic transparent at every path of leaf development. It was proposed that distinct vesicles-"crystals" in cytoplasm and vacuole and mass of them in crystal cells, vein bundles, and epidermal cells--all of them are lytic compartments. Later, obviously, true crystals are formed.     

Cell wall sheath surrounding calcium oxalate crystals in mulberry idioblasts

Summary. The distribution and ultrastructural features of idioblasts containing calcium oxalate crystals were studied in leaf tissues of mulberry, Morus alba L. In addition to the calcium carbonate crystals formed in epidermal idioblasts, large calcium oxalate crystals were deposited in cells adjacent to the veins and surrounded by a cell wall sheath which had immunoreactivity with an antibody recognizing a xyloglucan epitope. The wall sheath formation indicates exclusion of the mature crystal from the protoplast. Correspondence: Y. Sugimura, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido, Matsugasaki, Sakyo, Kyoto 606-8585, Japan.     

Low temperature-induced changes in the distribution of H2O2 and antioxidants between the bundle sheath and mesophyll cells of maize leaves

The distribution of antioxidants between bundle sheath and mesophyll cells of maize leaves was analysed in plants grown at 20 degrees C, 18 degrees C and 15 degrees C. The purity of the isolated bundle sheath and mesophyll fractions was determined using compartment-specific marker enzymes. In plants grown at 15 degrees C, ascorbate peroxidase, CuZn-superoxide dismutase (CuZn-SOD) and monodehydroascorbate reductase activities were increased in the bundle sheath cells, and glutathione reductase, dehydroascorbate reductase and monodehydroascorbate reductase activities were enhanced in the mesophyll cells. SOD was absent from the mesophyll of plants grown at 20 degrees C but an Fe-SOD activity was found in the mesophyll of plants grown at 15 degrees C. Foliar Mn-SOD activities were decreased at 15 degrees C compared to 20 degrees C. Catalase was undetectable in the mesophyll extracts of plants grown at 15 degrees C. Ascorbate and glutathione contents were considerably higher in the mesophyll than the bundle sheath fractions of plants grown at 20 degrees C. The ratios of reduced to oxidized forms of these antioxidants were significantly decreased in the bundle sheath, but increased in the mesophyll of leaves grown at 15 degrees C. Foliar H2O2 accumulated at 15 degrees C compared to 20 degrees C. Most of the foliar H2O2 was localized in the mesophyll tissues at all growth temperatures. The differential distribution of antioxidants between leaf bundle sheath and mesophyll tissues, observed at 20 degrees C, is even more pronounced when plants are grown at 15 degrees C and may contribute to the extreme sensitivity of maize to low temperatures.     

Development of secretory cells and crystal cells in Eichhornia crassipes ramet shoot apex

The distribution and development of secretory cells and crystal cells in young shoot apexes of water hyacinth were investigated through morphological and cytological analysis. The density of secretory cells and crystal cells were high in parenchyma tissues around the vascular bundles of shoot apexes. Three developmental stages of the secretory cells can be distinguished under transmission electron microscopy. Firstly, a large number of electron-dense vesicles formed in the cytoplasm, then fused with the tonoplast and released into the vacuole in the form of electron-dense droplets. As these droplets fused together, a large mass of dark material completely filled the vacuole. To this end, a secretion storage vacuole (SSV) formed. Secondly, an active secretion stage accompanied with degradation of the large electron-dense masses through an ill-defined autophagic process at periphery and in the limited internal regions of the SSV. Finally, after most storage substances were withdrawn, the materials remaining in the spent SSV consisted of an electron-dense network structure. The distribution and development of crystal cells in shoot apical tissue of water hyacinth were also studied by light and electron microscopy. Crystals initially formed at one site in the vacuole, where tube-like membrane structures formed crystal chambers. The chamber enlarged as the crystal grew in bidirectional manner and formed needle-shaped raphides. Most of these crystals finally occurred as raphide bundles, and the others appeared as block-like rhombohedral crystals in the vacuole. These results suggest that the formation of both secretory cells and crystal cells are involved in the metamorphosis of vacuoles and a role for vacuoles in water hyacinth rapid growth and tolerance.     

香樟叶肉含晶细胞季节变化研究

为探讨香樟(Cinnamomum camphora)叶肉含晶细胞超微结构的季节变化,阐明香樟叶肉中草酸钙晶体在春夏秋冬的变化规律。该研究以多年生香樟(C. camphora)叶片为材料,分别于春夏秋冬四个季节露地取样,制作超薄切片,用透射电子显微镜(TEM)观察叶肉含晶细胞超微结构的变化。结果表明:春季时香樟叶肉中只有少数细胞有草酸钙晶体,数量较少,晶体结构多为柱状晶、方晶; 夏季时香樟叶肉细胞中随机分布于液泡的草酸钙晶体明显比春季的数量多、体积大、形态丰富,晶体多为柱状晶、方晶、针晶、簇晶; 秋季时香樟叶肉细胞草酸钙晶体和夏季的类似,数量较多,形态多样,以方晶和柱状晶针晶为主,伴有晶簇; 冬季时香樟叶肉含晶细胞晶体形态为柱状晶、方晶、针晶,数量比夏季和秋季的数量略有减少。该研究结果表明在一年四季中香樟叶肉细胞液泡中均有草酸钙晶体结构存在。     

Crystals in sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.) leaves

Crystal-containing cells (C-cells) are widely spread in plant tissues; however, the origin of the crystals and their functions remain a subject of discussion. In sugar beet leaves, the membrane vesicles seen in an electron microscope appear in the cytoplasm and penetrate the vacuole by pinocytosis with the participation of tonoplast. In a light microscope, the vesicles fluoresce like crystals in C-cells. These crystal vesicles also fill the C-cells. The content of crystal vesicles is electron-transparent at all stages of leaf development. It is suggested that both individual crystal vesicles in the cytoplasm and in vacuoles and their agglomerations in C cells, vascular bundles, and epidermal cells are lytic compartments. Later, true crystals seem to be formed.     

小麦品系CP98(11)不同器官表皮蜡质组分和蜡质晶体结构的差异分析

为明确小麦不同器官表皮蜡质晶体结构和蜡质组分的差异,该研究以小麦品系CP98(11)为材料,在小麦扬花期分别取小麦的旗叶、叶鞘、穗下茎、花药和颖壳,利用气相色谱技术对各器官表皮蜡质组分进行鉴定,并通过扫描电镜观察其蜡质晶体结构。结果表明:(1)小麦不同器官的蜡质成分共鉴定出30种,主要为初级醇、二酮、烷烃、脂肪醛、脂肪酸、酯。(2)叶鞘、穗下茎、颖壳的蜡质中二酮含量最高,分别占蜡质总量的78.96%、67.03%和68.6%;花药的蜡质中烷烃含量最高(75.82%);旗叶的蜡质中初级醇含量最高(45.91%),其次为烷烃33.19%。(3)扫描电镜观察显示,旗叶正面的蜡质晶体呈片状结构,旗叶反面和颖壳的蜡质晶体结构呈片状与柱状混合的结构,花药的蜡质呈明显的波浪状结构,穗下茎和叶鞘的蜡质晶体呈柱状结构。     

EFFECTS OF 2,3,5-TRIIODOBENZOIC ACID ON THE STRUCTURE OF SOYBEAN LEAVES

The effects of 2,3,5-triiodobenzoic acid (TIBA) on soybean leaves (Glycine max. [L.] Merrill ‘Harosoy‘) include thickening with intensification of color and some raised intercostal regions, giving a wrinkled appearance. These effects are not restricted to early stages of leaf development but are pronounced during and after unfolding of the leaf. Proliferation of tracheary elements, increased procambial activity, and hypertrophy of bundle sheath extension cells occurred in the leaflet midvein of the youngest expanded leaf treated with 50 ppm or 100 ppm of TIBA. The youngest treated leaves exhibited differential growth rates and expansion within the palisade and spongy layers. Hypertrophy of spongy cells in these leaves occurred independently or simultaneously with elongation of the upper and lower palisade layers. The palisade and spongy tissues had undergone cell division and expansion at a greater pace than the epidermal layers. This, along with hypertrophy in the bundle sheath extension cells, would explain the wrinkled appearance of the lamina. The treated leaf became thicker than the control as a result of the increased number of cells in the spongy layer and elongation in the palisade layer. The observed aberrations in leaf structure suggest that TIBA interferes with some auxin-translocating system within the plant.     

植物晶体的形态结构、生物功能及形成机制研究进展

晶体是植物体内产生的一种具有特殊形态结构与生理功能的代谢物,其分布广泛,已在500多种植物中发现有晶体的存在。晶体形态多样,有针晶、柱晶、棱晶、砂晶、簇晶等;类型丰富,有草酸钙晶体、钟乳体、硅质体、硫酸钙晶体及其它类型的晶体;功能特殊,具有钙调节、植物保护和防御、重金属解毒、离子平衡、缓解逆境胁迫及其它多种生物功能。晶体的形成涉及钙离子的体外吸收和体内转运,草酸的生物合成,以及钙离子和草酸的耦合过程;晶体的生长发育涉及液泡、晶异细胞的调控及与其它细胞结构的相互协作。对晶体的研究进行综述,以期为晶体的进一步研究提供基础资料。     

Leaf permease1 gene of maize is required for chloroplast development.

Adjacent bundle sheath and mesophyll cells cooperate for carbon fixation in the leaves of C4 plants. Mutants with compromised plastid development should reveal the degree to which this cooperation is obligatory, because one can assay whether mesophyll cells with defective bundle sheath neighbors retain C4 characteristics or revert to C3 photosynthesis. The leaf permease1-mutable1 (lpe1-m1) mutant of maize exhibits disrupted chloroplast ultrastructure, preferentially affecting bundle sheath choroplasts under lower light. Despite the disrupted ultrastructure, the metabolic cooperation of bundle sheath and mesophyll cells for C4 photosynthesis remains intact. To investigate this novel mutation, the Activator transposon-tagged allele and cDNAs corresponding to the Lpe1 mRNA from wild-type plants were cloned. The Lpe1 gene encodes a polypeptide with significant similarity to microbial pyrimidine and purine transport proteins. An analysis of revertant sectors generated by Activator excision suggests that the Lpe1 gene product is cell autonomous and can be absent up to the last cell divisions in the leaf primordium without blocking bundle sheath chloroplast development.     

Calcium and oxalate content of the leaves of Phaseolus vulgaris at different calcium supply in relation to calcium oxalate crystal formation

Soluble and insoluble oxalate and insoluble calcium were measured in the leaves of Phaseolus vulgaris. The plants were grown in nutrient solutions with two different concentrations of calcium. Two developmental stages of the leaves were studied. Although the content of insoluble calcium differs widely according to leaf age and growth conditions, the percentage bound in crystals is nearly the same in all cases. In the growing leaves, concentrations of total oxalate are independent of calcium supply, thus, showing that the known rise in numbers of crystals, and of cells containing them, is not induced via oxalate biosynthesis. Fully expanded leaves contain more oxalate when grown in a nutrient solution with higher calcium concentration. Amounts of oxalate in percent of dry weight are similar to those given in the literature for other legume leaves.     

Processes modulating calcium distribution in citrus leaves. An investigation using x-ray microanalysis with strontium as a tracer

Citrus leaves accumulate large amounts of calcium that must be compartmented effectively to prevent stomatal closure by extracellular Ca2+ and interference with Ca(2+)-based cell signaling pathways. Using x-ray microanalysis, the distribution of calcium between vacuoles in different cell types of leaves of rough lemon (Citrus jambhiri Lush.) was investigated. Calcium was accumulated principally in palisade, spongy mesophyll, and crystal-containing idioblast cells. It was low in epidermal and bundle sheath cells. Potassium showed the reverse distribution. Rubidium and strontium were used as tracers to examine the pathways by which potassium and calcium reached these cells. Comparisons of strontium and calcium distribution indicated that strontium is a good tracer for calcium, but rubidium did not mirror the potassium distribution pattern. The amount of strontium accumulated was highest in palisade cells, lowest in bundle sheath and epidermal cells, and intermediate in the spongy mesophyll. Accumulation of strontium in palisade and spongy mesophyll was accompanied by loss of potassium from these cells and its accumulation in the bundle sheath. Strontium moved apoplastically from the xylem to all cell types, and manipulation of water loss from the adaxial leaf surface suggested that diffusion is responsible for strontium movement to this side of the leaf. The results highlight the importance of palisade and spongy mesophyll as repositories for calcium and suggest that calcium distribution between different cell types is the result of differential rates of uptake. This tracer technique can provide important information about the ion uptake and accumulation properties of cells in intact leaves.