Reproductive and vegetative morphology of Polyptera (Juglandaceae) from the Paleocene of Wyoming and Montana

The morphology, systematics, and ecology of the extinct juglandaceous genus Polyptera are interpreted on the basis of infructescences, fruits, staminate catkins, pollen, and compound leaves from the Paleocene of Wyoming and Montana. The elongate infructescences of Polyptera manningii bear numerous helically arranged sessile fruits. The fruit is a pyramidal nut with a vascularized husk and a multilobed disk-like wing adaptive for wind dispersal. Associated staminate catkins bear numerous helically arranged florets, each with six or more stamens. Pollen from the anthers is triporate and isopolar, with ultrastructure diagnostic of Juglandaceae, but with a pattern of exinous thinning characteristic of the extinct dispersed pollen type Maceopolipollenites anellus (Nichols et Ott) comb. nov. The correlated leaves, Juglandiphyllites glabra (Brown ex Watt) comb. nov., are deciduous, pinnately compound, and have five to seven petiolulate finely serrate leaflets. Systematically, Polyptera shows relationships both with the Hicorieae and the Juglandeae. Occurrences in the Torrejonian and Tiffanian stages of the Paleocene place Polyptera as the oldest unequivocal record of Juglandaceae. Polyptera manningii typically occurs in low-diversity assemblages of 8-15 species, and usually is a dominant or subdominant constituent of floodplain assemblages. It may have been an early-successional colonizer.     

Colonization pattern of aquatic hyphomycetes on leaf packs in subtropical stream

Steralized leaf pieces of eight plants (Eucalyptus rostrata, Phoenix dactylifera, Phragmites australis, Musa nana, Salix subserrata, Cyperus alopecuroides, Ricinus communis and Eichhornia crassipes) were submerged in the Nile stream. Thirty-nine species of aquatic hyphomycetes were colonized on the plant leaves. Eucalyptus was the best substratum (30 species) for colonization by aquatic hyphomycetes. Phoenix (14 species), Phragmites (11 species), Salix (9 species), Musa (8 species), Ricinus and Cyperus (6 species) were also good substrata for aquatic hyphomycetes colonization. Echhornia (aquatic plant) was not suitable for aquatic hyphomycetes colonization. Alatospora acuminata, Triscelophorus monosporus and Tetracladium marchalianum were found to be the major colonizers on all leaf materials. Temperature and dissolved oxygen were the highest physico-chemical parameters affecting the aquatic hyphomycetes colonization. These results indicate that aquatic hyphomycetes have been shown to be successful colonizers on plants leaf in river Nile in Egypt as subtropical region. This revised version was published online in June 2006 with corrections to the Cover Date.     

Cadmium effects on leaf transpiration of sugar beet (Beta vulgaris)

Seedlings of sugar beet ( Beta vulgaris L. cv Monohill) were cultivated for 4 weeks in nutrient solution containing different concentrations of CdCl₂ (0 to 10 μ M ). The effects of Cd on appearance and function of stomata and leaf cuticle were investigated by water loss measurements and microscopy. The leaf transpiration rate increased with increasing Cd concentrations while the sum total of stomatal aperture area per unit leaf area decreased. Already at low Cd levels. an increase of defective and undeveloped stomata was found in Cd treated plants. These stomata are closed or have small apertures and probably lack a functional closing mechanism. The number of intact stomata per unit leaf area was lower in leaves of Cd treated plants than in controls, and Cd induced closure of intact stomata. The total number of stomata per leaf area slightly increases with increasing Cd concentration. as does the percentage of small stomata. Furthermore. specific leaf area increased, while the density of leaf structure was decreased by Cd. From this observation we conclude that the increase in transpiration rate caused by Cd is primarily due to effects on the permeability of the leaf cuticle to water.     

Factors affecting gene expression of patatin and proteinase-inhibitor-II gene families in detached potato leaves:

In whole intact potato (Solanum tuberosum L.) plants, the gene families of class-I patatin and proteinase inhibitor II (Pin 2) are constitutively expressed in the tubers. However, they are also induced in detached potato leaves in the presence of light. To further characterize this light action, the detached leaves were subjected to monochromatic light of different wavelengths and to darkness in the presence of metabolites and inhibitors. Patatin genes could be induced by the simultaneous application of sucrose (sugars) and glutamine in darkness. Neither of these metabolites was active when supplied alone. When photosynthesis was blocked by 3-(3,4-Di-chlorophenyl)-1, 1-dimethylurea (DCMU) in the light, patatin genes were not expressed; however, the inhibition was overcome in the presence of sucrose. This indicates that besides its role in photosynthetic carbohydrate production, light may be essential for the supply of amino acids (or reduced nitrogen). Unlike patatin, Pin 2 genes were, to a small extent, also active in darkness, and sucrose weakly enhanced this expression. However, DCMU did not affect Pin 2 expression in the light. Both abscisic acid and methyl jasmonate strongly promoted the accumulation of Pin 2 mRNA independent of the light conditions, indicating that the gene family is probably under hormonal control. The phytohormones did not affect patatin gene expression. Inhibitors of cytosolic (cycloheximide) and organellar (chloramphenicol) translation had opposite effects on the two gene families. Careful evaluation of the inhibitors' action indicates that protein synthesis (cytosol) is required for the expression of Pin 2 genes but not for the patatin genes. These results clearly demonstrate that, although in situ both gene families are constitutively expressed in the same plant organ (tuber) in intact plants, their expression is mediated by different factors.Abbreviations ABA cis-abscisic acid - DCMU 3-(3,4-dichlorphenyl)-1,1-dimethylurea - GUS -glucuronidase activity - MeJA methyl jasmonate - Pin 2 proteinase inhibitor II We thank Beate Küsgen and Regina Breitfeld for the greenhouse work. This work was supported by a grant from the Bundesministerium für Forschung und Technologie.     

Cysteine, γ-glutamyl-cysteine and glutathione contents of spinach leaves as affected by darkness and application of excess sulfur. II. Glutathione accumulation in detached leaves exposed to H2S in the absence of light is stimulated by the supply of glycine to the petiole

When illuminated leaf discs and detached leaves of spinach ( Spinacia oleracea L. cv. Estivato) were exposed to 0.4 and 0.25 μl 1^-1 H₂S, respectively, pool sizes of cysteine and glutathione increased. In the dark, apart from these compounds, the level of γ-glutamyl-cysteine also increased. Incubation of leaf discs with 1.0 m M buthionine sulfoximine (BSO) resulted in the accumulation of cysteine only, both in the light and in darkness. When glycine was supplied to the petioles of detached leaves exposed to H₂S in the dark, the accumulation of glutathione was stimulated, while γ-glutamyl-cysteine accumulation was prevented completely. Glycolate and glyoxylate, precursors of glycine in the glycolate pathway, had nearly the same effect as glycine. Although other amino acids were apparently taken up equally well as glycine when supplied to the petiole, they were much less effective, or not effective at all, in restoring glutathione synthesis in the dark. These results provide evidence, that H₂S-induced glutathione accumulation in spinach leaves in the dark is limited by the availability of glycine, giving rise to the accumulation of the metabolic precursor γ-glutamyl-cysteine.     

Benzyladenine-induced increase in DNA content in the nucleus of bean leaf cells

Primary leaves of bean plants (Phaseolus vulgaris L.) were treated with benzyladenine (BA) from 7 days after sowing. Nuclei were isolated and the DNA content per nucleus was determined. BA increased the amount of DNA per nucleus of untreated controls by about 50% without nuclear division.     

Physiological effects of long term exposure to low concentrations of SO2 and NH3 on poplar leaves

Shoots of poplar (Populus euramericana L. cv. Flevo) were exposed to filtered air, SO₂, NH₃ or a mixture of SO₂ and NH₃ for 7 weeks in fumigation chambers. After this exposure gas exchange measurements were carried out using a leaf chamber. As compared to leaves exposed to filtered air, leaves pretreated with 112 μg m^?3 SO₂ showed a small reduction in maximum CO₂ assimilation rate (P_max) and stomatal conductance (g_s). They also showed a slightly higher quantum yield and dark respiration. In addition, the fluorescence measurements indicated that the Calvin cycle of the leaves pretreated with 112 μg m^?3 SO₂ was more rapidly activated after transition from dark to light. An exposure to 64 μg m^?3 NH₃ had a positive effect on P_max, stomatal conductance and NH₃ uptake of the leaves. This positive effect was counteracted by an SO₂ concentration of 45 μg m^?3. The exposure treatments appeared to have no effect on the relationship between net CO₂-assimilation and g_s. Also, no injury of the leaf cuticle or of epidermal cells was observed. Resistance analysis showed that NH₃ transfer into the leaf can be estimated from data on the boundary layer and stomatal resistance for H₂O transfer and NH₃ concentration at the leaf surface, irrespective of whether the leaves are exposed for a short or long time to NH₃ or to a mixture of NH₃ and SO₂. In contrast SO₂ uptake into the leaves was only partly correlated to the stomatal resistance. The results suggest a large additional uptake of this gas by the leaves. The possibility of a difference in path length between SO₂ and H₂O molecules is proposed.     

Distribution of anthocyanins in aceraceae leaves

The distribution of anthocyanins in spring sprouted and/or autumn coloured leaves of Dipteronia sinensis and Acer (119 taxa) was studied.

Dipteronia contained four cyanidin glycosides: the 3-glucoside, 3-rutinoside, 3-galloylglucoside and 3,5-diglucoside. Acer contained five cyanidin glycosides: 3-glucoside, 3-rutinoside, 3-galloylglucoside, 3-galloylrutinoside and 3,5-diglucoside, two delphinidin glucosides: 3-glucoside and 3-rutinoside and three unidentified anthocyanins. Both Dipteronia and Acer contained the recently reported cyanidin 3-galloylglucoside. The anthocyanin constituents in spring leaves were more complex than those found in autumn coloured leaves: nine in spring and six in autumn. The presence/absence of the major anthocyanins in the spring sprouted leaves of 111 Acer taxa analysed were grouped into 17 distribution patterns. In the autumn the number of anthocyanin distribution patterns was found to be 11. In Acer, cyanidin glycosides were found in 20 sections and delphinidin glycosides in 17 out of the 21 sections analysed. Although the distribution of anthocyanins showed no clear relations among sections, delphinidin glycosides were mainly found in sections Macrantha, Goniocarpa and Saccharina. There were no differences in the pigment constituents in the species native to different countries, such as A. rubrum in North America and A. pycnanthum in Japan, both containing the same pigments: cyanidin 3-glucoside, 3-rutinoside, 3-galloylglucoside, 3-galloylrutinoside and 3,5-diglucoside.     

九龙江口秋茄（Kandelia candel）红树林掉落叶自然分解与落叶腐解微生物的关系

 通过对九龙江口秋茄红树林人工模拟凋落叶自然分解过程中落叶腐解与落叶腐解微生物变化的研究,结果表明：1．随落叶分解进程,落叶腐解微生物数量有了显著地变化;就细菌、放线菌和丝状真菌等三大类群微生物数量来看,整个过程以细菌占绝对优势,其数量在200×104一8800×104个／克干重,占三大类群微生物总数量的96—99%以上。这表明细菌是落叶分解起主要作用的微生物类群。2．微生物各生理类群中,以氨化细菌数量最多,在26×104一180×104个／克干重;而亚硝化细菌,反硝化细菌及纤维分解菌分别仅在0.03×104一0.24×104,0.03×104一0.10×104及1.14×104一7.33×104个／克干重。表明氨化细菌是有机物质无机化的主要生理类群。并且氨化作用、亚硝化作用和反硝化作用是同时进行;并随落叶腐解周期的延长(半腐解周期内)而加强,唯强度不一,它反映了该生境干、湿交替的沼泽化特点。纤维分解菌数量的变化较特殊,在落叶腐解第2周时,有了明显增多,至第4周达全周期的最高值,而以后周期都与初始叶面纤维分解菌的数量相近,甚至减少。从微生物活性的变化测定结果来看,与上述微生物生理类群的变化特点是相一致的。3．在该生境中,落叶腐解速度是很快的,当落叶入土1周后将近1／4有机物被腐解,至第6周达半腐解状态。随落叶腐解有机物质无机化程度的加速,残叶中单位叶重的可溶性总糖含量和全磷量都明显地减少,而全氮含量显著地增加。     

Physiological effects of long-term exposure to low and moderate concentrations of atmospheric NH3 on poplar leaves

Abstract. Poplar shoots ( Populus euramericana L.) obtained from cuttings were exposed for 6 or 8 weeks to NH₃ concentrations of 50 and 100 μgm⁻³ or filtered air in fumigation chambers. After this exposure the rates of NH₃ uptake, transpiration, CO₂ assimilation and respiration of leaves were measured using a leaf chamber. During the long-term exposure also modulated chlorophyll fluorescence measurements were carried out to obtain information about the photosynthetic performance of individual leaves. Both fluorescence and leaf chamber measurements showed a higher photosynthetic activity of leaves exposed to 100 μg NH₃ m⁻³. These leaves showed also a larger leaf conductance and a larger uptake rate of NH₃ than leaves exposed to 50 μg m⁻³ NH₃ or filtered air. The long-term NH₃ exposure did not induce an internal resistance against NH₃ transport in the leaf, nor did it affect the leaf cuticle. So, not only at a short time exposure, but also at a long-term exposure NH₃ uptake into leaves can be calculated from data on the boundary layer and stomatal resistance for H₂O and ambient NH₃-concentration. Furthermore, the NH₃ exposure had no effect on the relation between CO₂-assimilation and stomatal conductance, indicating that NH₃ in concentrations up to 100 μg m⁻³ has no direct effect on stomatal behaviour; for example, by affecting the guard or contiguous cells of the stomata.