Inositol 1,4,5-trisphosphate formation in leaves of winter oilseed rape plants in response to freezing, tissue water potential aed abscisic acid

Time courses of formation of inositol 1,4,5-trisphosphate (IP₃) were followed in the leaves of non-acclimated and cold (2°C)-acclimated winter oilseed rape ( Brassica napus L. var. oleifera ) plants, subjected to different freezing temperatures or to polyethylene glycol 8000 (PEG) and abscisic acid (ABA) treatments. Changes in water potential (Ψ_w) and in ABA level in the frost- and PEG-treated tissues were also determined. Results obtained indicate that temperatures sligthly higher than LT₅₀ induced a transient and substantial increase in IP₃ level, both in non-acclimated and cold-acclimated tissues. At comparable freezing temperature (–5°C) the response of cold-acclimated leaves was lower than that of non-acclimated ones. The PEG-depedent decrease in Ψ_w to –0.9 MPa or ABA (0.1 m M ) treatment gave rise to a transient increase in IP₃ content in non-acclimated tissues only. Collectively, the data indicate that cold acclimation of plants may lead to lower cell responsiveness to the factors studied in terms of induction of IP₃ formation. Changes in the IP₃ content, observed in the present experiments, support our previous suggestion that non-killing freezing temperatures may induce the phosphoinositide pathway, both in non-acclimated and cold-acclimated tissues. Lowering of tissue water potential to some threshold value or a high exogenous ABA supply may mimic the freezing-dependent reaction in the non-acclimated leaves.     

Effect of increased CO2 concentration and temperature on the phyllosphere mycoflora of winter wheat flag leaves during ripening

The impact of elevated carbon dioxide (CO₂, 600/700 μmol mol^-1) and temperature (+ 4°C) on phyllosphere fungi colonising flag leaves of mini crops of winter wheat cv. Mercia between anthesis and harvest was determined in a computer-controlled environment facility in 1993 and 1994. In both years the total fungal populations (cm² leaf) were found to have increased due to exposure to either elevated CO₂ and elevated CO₂+ temperature treatments. This was mainly due to significant increases in populations of Cladosporium spp. (C. cladosporioides and C. herbarum) on the flag leaves during ripening. Other phyllosphere component species such as white and pink yeasts were not markedly affected by treatments. The range of fungal species found in such controlled environment chambers was narrower than that commonly found on flag leaves of field grown crops. Common and important colonisers of leaves and ripening ears such as Aureobasidium pullulans, Epicoccum nigrum and Fusarium spp. were seldom isolated.     

Traits of transgenic Atropa belladonna doubly transformed with different Agrobacterium rhizogenes strains

Hairy root cultures of Atropa belladonna L. were established by infection either with Agrobacterium rhizogenes ATCC 15834 or MAFF 03-01724, and transgenic plants were obtained from both hairy root cultures. Doubly transformed roots were induced by re-infection of the leaf segments of transgenic Atropa belladonna plants (A. rhizogenes 15834) with MAFF 03-01724. Shoots and viviparous leaves were regenerated from the doubly transformed roots. The genetic transformation was determined by the opine assay (agropine, mannopine and/or mikimopine) and polymerase chain reaction. Physiological changes and tropane alkaloid biosynthesis in the hairy roots (singly and doubly transformed) were investigated. The alkaloid content in the doubly transformed root strain was intermediate as compared to the root strains which were singly transformed. On the other hand endogenous IAA levels in doubly transformed roots were significantly decreased compared to both singly transformed roots.Abbreviations BA benzyladenine - IAA indoleacetic acid - NAA naphthaleneacetic acid - PCR polymerase chain reaction - t-ZR trans-zeatin     

A simple classification of the complex parts of vascular plants

Four operational morphological units are defined to characterize 'typical' stems, leaves, roots and hairS. Any complex part can be classified among these OMUs by a graphical representation or by a quadruplet suitable for computer-aided analyses. Thirty-nine examples are given, suggesting a continuous view of plant morphology.     

Foliar flavonoids of eastern North AmericanVitis (Vitaceae) north of Mexico

Twenty-one flavonoid glycosides were isolated from the leaves of 22 North AmericanVitis L. taxa, representing two subgenera and five series. Three chemical groups were evident: one producing flavonols, flavones, and C-glycosylflavones, a second producing flavonols and flavones, and a third producing only flavonols. These three chemical groups did not correspond to any of the subgeneric groupings based on morphology. However, flavonoid distributions within series in each subgenus correlate well with morphological data. Parallel flavonoid evolution within each series is thought to account for this lack of subgeneric and interserial flavonoid distinction. The flavonoid data indicate that seriesCordifoliae of subgenusVitis, particularlyV. vulpina L., is the most closely related group to subgenusMuscadinia (Planch.)Rehder, and represents an evolutionary link between the two subgenera.     

Effects of light and regulators on senescence-related changes in soluble proteins in detached oat (Avena sativa L.) leaves

The rate of senescence and the two-dimensional pattern of soluble proteins from detached oat leaves senescing in either darkness or light were analyzed, and compared to those of leaves in which senescence was delayed by application of the cytokinin benzyladenine or enhanced through the action of abscisic acid.Senescence of detached leaves in light did not differ significantly from senescence in attached leaves on intact plants. In darkness, protein was lost at a higher rate than in light, but several individual proteins showed relative increases. Notably, proteins previously characterized as high-molecular-weight proteins and senescence-associated proteins (Klerk et al., 1992) increased. Changes observed during incubation in light or darkness appeared to be related to this condition rather than the rate or progress of senescence. Cytokinins delayed and abscisic acid accelerated the changes in protein pattern compared to water. Beside changes previously identified in leaves senescing on the plant, detached leaves show alterations that reflect their condition of incubation rather than their developmental progress.Abbreviations 2D-PAG two-dimensional polyacrylamide gel electrophoresis - ABA abscisic acid - BA N⁶-benzyladenine - BSA bovine serum albumin - EDTA ethylenediamine tetraacetic acid - IEF isoelectric focusing - Rubisco ribulosebisphosphate carboxylase/oxygenase - SDS sodium dodecyl sulfate - Tris tris (hydroxymethyl) aminomethane     

Low temperature phototransformations of protochlorophyll(ide) in etiolated leaves

By methods of difference and derivative spectroscopy it was shown that in etiolated leaves at 77 K three photoreactions of P650 protochlorophyllide take place which differ in their rates and positions of spectral maxima of the intermediates formed in the process: P650R668, P650R688, and P650R697. With an increase of temperature up to 233 K, in the dark, R688 and R697 are transformed into the known chlorophyllide forms C695/684 and C684/676, while R668 disappears with formation of a shorter wavelength form of protochlorophyllide with an absorption maximum at 643–644 nm.Along with these reactions, at 77 K phototransformations of the long-wave protochlorophyllide forms with absorption maxima at 658–711 nm into the main short-wave forms of protochlorophyllide are observed. At 233 K in the dark this reaction is partially reversible. This process may be interpreted as a reversible photodisaggregation of the pigment in vivo.The mechanism of P650 reactions and their role in the process of chlorophyll photobiosynthesis are discussed.Abbreviations P650 protochlorophyll(ide) with absorption maximum at 650 nm - C697/684 chlorophyllide with fluorescence maximum at 695 nm and absorption maximum at 684 nm - R697 intermediate with absorption maximum at 697 nm     

茶叶中总硒含量及其影响因素的研究

茶叶中硒素总量测定结果表明：土壤含硒量的高低是直接影响茶叶中硒的总量。茶树根、茎、叶、果中均有硒元素,叶片是茶硒积累的主要器官,尤其是老叶,其含量是嫩叶的几倍．茶树品种间含量的差异显著,最大差异达10倍以上．毛茶加工的成品茶含硒量受加工技术措施影响较大,其不同等级的含硒量与级别没有线性关系．     

寄生蜂种群繁殖分布时间特征的研究

运用１０种寄生蜂的２３张生殖力表资料,分析比较了这些种群繁殖分布的特征．结果表明,寄生蜂种群繁殖具有相似的分布特征,种群繁殖集中分布在生殖头ｄ天内,在生殖头ｄ／２天内繁殖分布更为集中．在生殖头ｄ天内种群繁殖对种群增长的贡献几乎均达到１００％,其中大部分贡献是在生殖头ｄ／２天内实现的．这种繁殖分布特征对于寄生蜂种群内禀增长率的测定和掌握种群数量动态的时间特性十分重要．本文结合Ｉｗａｏ零频率法和Ｇｅｒｒａｒｄ阈限密度法,提出一种改进的种群密度估计方法──“综合阈限密度估计法”,并由此探讨了苹果树上山楂叶螨成螨的密度估计及其抽样技术．采用零样频率来估计成螨的平均密度,并得到用概率保证的理论抽样数模型．比较结果表明,零频率法所需的理论抽样数少于直接计数法．综合阈限密度估计法的拟合效果更为显著．     

山楂叶螨种群空间格局及其应用的研究Ⅱ．成螨种群密度综合估计及其抽样技术

本文结合Ｉｗａｏ零频率法和Ｇｅｒｒａｒｄ阈限密度法,提出一种改进的种群密度估计方法──“综合阈限密度估计法”,并由此探讨了苹果树上山楂叶螨成螨的密度估计及其抽样技术．采用零样频率来估计成螨的平均密度,并得到用概率保证的理论抽样数模型．比较结果表明,零频率法所需的理论抽样数少于直接计数法．综合阈限密度估计法的拟合效果更为显著．