Epi- and intracuticular lipids and cuticular transpiration rates of primary leaves of eight barley (Hordeum vulgare) cultivars

The major constituents of the epi- and intracuticular lipids of primary leaves of 8 cultivars of barley ( Hordeum vulgare L.) have been studied together with cuticular transpiration rates. The total amount of analysed cuticular lipids ranged from 9.6 to 13.4 μg cm⁻² and was dominated by the epicuticular fraction, which made up 73–84% of the total. There were variations in the percentages of the analysed lipid classes, alkanes, esters, aldehydes, β-diketones and alcohols, between epi- and intracuticular lipids among individual cultivars, but no clear tendency in these variations, except for the aldehydes, was found. The epicuticular lipids were richer in aldehydes than the intracuticular lipids. The cuticular transpiration rates were poorly correlated with the levels or composition of epi-, intra- or total cuticular lipids. The cuticular transpiration rates were considerably altered as a response to a water stress treatment, but these changes could not be correlated with any changes in amount or composition of the cuticular lipids. From these results it is concluded that some property other than amount or composition of cuticular lipids is the most important in regulation of water diffusion through the cuticle.     

Organophosphate induced chlorophyll mutations in Hordeum vulgare

Summary Ten Organophosphorus (OP) insecticides are tested for their genetic toxicology in the Hordeum vulgare system. Of these, 8 OPs induced chlorophyll mutations of which 6 are new discoveries.     

Light and electron microscope studies on pollen development in barley (Hordeum vulgare L.) grown under copper-sufficient and deficient conditions

Abstract. Pollen development in copper-deficient barley plants is highly irregular resulting in low and variable pollen fertility. The main cause of this sterility was found to be the abnormal development of the tapetum which becomes expansionary and invasive as the pollen develops. The ultrastructure of both tapetum and microspores is different from that of control material with irregularities of exine deposition, endopolyploidy of tapetal nuclei and an alteration of organelle composition being correlated with low fertility.     

Characteristics of a photorespiratory mutant of barley (Hordeum vulgare L.) deficient in phosphogly collate phosphatase

A barley mutant RPr84/90 has been isolated by selecting for plants which grow poorly in natural air, but normally in air enriched to 0.8% CO₂. After 5 minutes of photosynthesis in air containing¹⁴CO₂ this mutant incorporated 26% of the¹⁴C carbon into phosphoglycollate, a compound not normally labelled in wild type (cv. Maris Mink) leaves.The activity of phosphoglycollate phosphatase (EC 3.1.1.18) was 1.2 nkat mg^–1 protein at 30°C in RPr 84/90 compared to 19.2 nkat mg^–1 protein in the wild-type leaves. Phosphoglycollate phosphatase activity was not detected after protein separation by electrophoresis of leaf extracts from the mutant on polyacrylamide gels; on linear 5% acrylamide gels three bands with enzyme activity were separated from extracts of wild type plants. Gradient gel electrophoresis followed by activity staining showed two bands in Maris Mink tracks of MW 86,000 and 96,000, but no bands in 84/90. This is the first report of isozymes of phosphoglycollate phosphatase in barley which were absent in the mutant extracts. Our results confirm an earlier report of isozymes of this phosphatase in Phaseolus vulgaris [18].The photosynthetic rate of RPr 84/90 in 1% O₂, 350 l CO₂ l^–1 was 9–12 mg CO₂ dm^–2 h^–1 at 20°C, whereas the wild-type rate was 27–29 mg CO₂ dm^–2 h^–1 at 20°C. In 21% O₂, 350 l CO₂ l^–1 the rate was 2–3 mg CO₂ dm^–2 h^–1 in the mutant and 20 mg CO₂ dm^–2 h^–1 in the wild type.Genetic analysis has shown that the mutation segregates as a single recessive nuclear gene.     

Characterization of a gibberellin sensitive dwarf mutant of barley (Hordeum vulgare L.,Mut. Dornburg 576)

The radiation (³²P) induced dwarf mutant of spring barley,Hordeum vulgare L., Mut. Dornburg 576, was genetically studied by crosses with the mother variety and characterized by seedling assays and investigations on development and yield formation. In comparison to the normal mother variety (Hordeum vulgare L., cv. Saale) mutant plants exhibit drastically reduced culm length, intensive tillering, a prolonged life cycle and a smaller biomass and grain yield formation. These characters are controlled by one gene in a pleiotropic way. The mutant responds with normal growth and development to the application of gibberellins.     

Chlorophyll b to chlorophyll a conversion precedes chlorophyll degradation in Hordeum vulgare L.

This study reveals by in vivo deuterium labeling that in higher plants chlorophyll (Chl) b is converted to Chl a before degradation. For this purpose, de-greening of excised green primary leaves of barley (Hordeum vulgare) was induced by permanent darkness in the presence of heavy water (80 atom % (2)H). The resulting Chl a catabolite in the plant extract was subjected to chemical degradation by chromic acid. 3-(2-Hydroxyethyl)-4-methyl-maleimide, the key fragment that originates from the Chl catabolite, was isolated. High resolution (1)H-, (2)H-NMR and mass spectroscopy unequivocally demonstrates that a fraction of this maleimide fragment consists of a mono-deuterated methyl group. These results suggest that Chl b is converted into Chl a before degradation. Quantification proves that the initial ratio of Chl a:Chl b in the green plant is preserved to about 60-70% in the catabolite composition isolated from yellowing leaves. The incorporation of only one deuterium atom indicates the involvement of two distinguishable redox enzymes during the conversion.     

Reinvestigation of the chlorophyll distribution among the chlorophyll-proteins and chlorophyll-protein complexes of Hordeum vulgare L.

Solubilization of barley (Hordeum vulgare L.) thylakoid membranes with sodium dodecylsulphate plus sodium deoxycholate with or without Triton X-100 and subsequent fractionation in the polyacrylamide gel electrophoresis system described in this paper resulted: (1) in the resolution of the chlorophyll-proteins and chlorophyll-protein complexes commonly known as CP1a, CP1, LHCP¹, LHCP², CPa and LHCP³; (2) in the highly increased stability of CP1 and CP1a, as judged by their chlorophyll content, (3) at the expense of the free pigment concentration (4) which could be reduced to a negligible amount. Some 40% of the total chlorophyll contained in the mature higher plant thylakoid membrane is associated with CP1 and CP1 a and as already suggested before [19] no significant amount of free chlorophyll occurs in vivo.Abbreviations chl chlorophyll - CP1 P₇₀₀-chla-protein - CPa P680-chla-protein - DOC sodium deoxychlolate - FC free chlorophyll - LHCP light-harvesting chlorophyll a/b-protein - PAGE(S) polyacrylamide gel electrophoresis (system) - SDS sodium dodecylsulphate - TX-100 Triton X-100     

Characterization of two chlorophyll b-deficient,azide-derived mutants of Hordeum vulgare cv. Maris Mink

Two mutant lines of Hordeum vulgare cv. Maris Mink (designated RChl 46 and 47) deficient in chlorophyll b have been isolated following azide mutagenesis. Two major thylakoid membrane proteins of molecular weight 25 and 26 k daltons are absent from the mutant plants following analysis by SDS gel electrophoresis, presumably due to a lack of the light harvesting chlorophyll a/b complex. The photosynthetic capabilities of the wild type and mutant lines were very similar.     

PCR detection of Hordeum bulbosum introgressions in an H. vulgare background using a retrotransposon-like sequence

Retrotransposon-like sequences are ideal tools for initial screening assays to distinguish between closely related species because of their ubiquitous presence, high copy number, chromosome coverage and rapid sequence evolution. A retrotransposon-like sequence, pSc119.1, cloned from Secale cereale (rye) has been used to obtain PCR primers that are capable of detecting small introgressions of Hordeum bulbosum (bulbous barley grass) chromatin in a Hordeum vulgare (cultivated barley) background. Combining this PCR-based assay with a crude but effective high-throughput DNA extraction has enabled the rapid identification of plants possessing H. bulbosum introgressions from large numbers of progeny from H. vulgare×H. bulbosum crosses. These plants are then further characterized by more-refined cytological, molecular and pathological techniques to locate and map the introgressed chromatin and to evaluate their disease resistance. Received: 18 April 2001 / Accepted: 23 August 2001     

Clonal analysis of the development of the barley (Hordeum vulgare L.) leaf using periclinal chlorophyll chimeras

Barley seedlings that show mosaic expression of chlorophyll were selected from the progenies of mutagenized seeds. The sectored plants were grown under conditions that lead to the formation of lateral tillers, and a fraction of these had different kinds of leaf variegation. These sectorially and periclinally chimeric shoots were used to analyze the cellular organization of the barley shoot apex and the clonal development of the leaf. The shoot apex is organized in two cell lineages, L1 and L2. As well as giving rise to the epidermis, the L1 layer contributes to leaf mesophyll, particularly at the margins, but, on the adaxial side of leaf laminae, also in more central positions. The L1 layer alone is responsible for the formation of the hood, a flower homologue structure present in strains homozygoous for the dominant allele at the K (hooded ) locus. The relative contribution of L2 to leaf formation decreases in younger tillers and during tiller development from the basal to the flag leaf. Chimerism of the plants was generated by non-transmissible somatic events or by nuclear mutations. Received: 28 May 1998 / Accepted: 20 July 1998     

Biotransformation of podophyllotoxin by Hordeum vulgare cell suspension cultures

Hordeum vulgare cell suspension cultures were used to modify podophyllotoxin (1) One major product (1a) and one minor product (1b) were detected in both the culture medium and cells. To optimize the yield of compound 1a, we showed that: (1) the optimal concentration of added podophyllotoxin (1) was 33 mg L^-1; higher concentrations caused cell toxicity; (2) the stage of the cell cycle (lag/log/stationary) at which podophyllotoxin was added only marginally affected the yield of compound 1a; the optimal addition time was after lag phase, in which the yield of compound 1a reached ca. 76%, and (3) biotransformation of podophyllotoxin (1) was relatively slow; podophyllotoxin fed at 4 days after subculture resulted in yields of compound 1a of ca. 56, 64 and 76% after an additional 3, 6 and 10 days of incubation, respectively. Product 1a was purified and identified as isopicropodophyllone (1a) based on MS and NMR data.     

Alterations in light-induced stomatal opening in a starch-deficient mutant of Arabidopsis thaliana L. deficient in chloroplast phosphoglucomutase activity

Stomatal responses to light of Arabidopsis thaliana wild-type plants and mutant plants deficient in starch (phosphoglucomutase deficient) were compared in gas exchange experiments. Stomatal density, size and ultrastructure were identical for the two phenotypes, but no starch was observed in guard cells of the mutant plants whatever the time of day. The overall extent of changes in stomatal conductance during 14 h light–10 h dark cycles was similar for the two phenotypes. However, the slow endogenous stomatal opening occurring in darkness in the wild type was not observed in the mutant plants. Stomata in the mutant plants responded much more slowly to blue light (70 μmol m^?2 s^?1) though the response to red light (250 μmol m^?2 s^?1) was similar to that of wild-type plants. In paradermal sections, stomatal responses to red light (300 μmol m^?2 s^?1) were weak for wild-type plants as well as for mutant plants. Stomatal opening was greater under low blue light (75 μmol m^?2 s^?1) than under red light for the two genotypes. However, in mutant plants, a high chloride concentration (50 mol m^?3) was necessary to achieve the same stomatal aperture as observed for the wild-type plants. These results suggest that starch metabolism, via the synthesis of a counter-ion to potassium (probably malate), is required for full stomatal response to blue light but is not involved in the stomatal response to red light.     

Isolation and characterization of a urobilinogenoidic chlorophyll catabolite from Hordeum vulgare L

A new type of chlorophyll catabolite was isolated from extracts of de-greened primary leaves of barley (Hordeum vulgare cv. Lambic). Its constitution was elucidated by one-dimensional and two-dimensional [(1)H,(13)C]-homo- and heteronuclear NMR spectroscopic techniques and by high resolution mass spectroscopy. The isolated catabolite, a water-soluble, colorless, and nonfluorescent linear tetrapyrrole, resembles urobilinogen in which one of the propionic side chains forms a five membered isocylic ring system, indicating its origin from the chlorophylls.     

Ammonia compensation points in two cultivars of Hordeum vulgare L. during vegetative and generative growth

The NH₃ compensation point (χ_NH3) in Hordeum vulgare cvs Golf and Laevigatum was determined at different growth stages under controlled environmental conditions. The plants were grown to maturity in hydroponics under N limitation. When plants were exposed to NH₃ at realistic ambient levels ranging from 0 to 25 nmol NH₃ mol^?1 air at an air temperature of 20°C, a significant (P < 0.001) linear correlation between the NH₃ flux and the atmospheric NH₃ mole fraction was observed, showing a constant conductivity to NH₃ exchange irrespective of the NH₃ level. For both cultivars a marked decrease in χ_NH3 was observed in the period from tillering to anthesis. In cv. Golf, χ_NH3 decreased from 6.4 ± 1.1 to 3.0 ± 0.4 nmol NH₃ mol^?1 air, while χ_NH3 in cv. Laevigatum dropped from 4.2 ± 0.3 nmol NH₃ mol^?1 air to below the detection limit (< 0.9 nmol NH₃ mol^?1 air). The NH₃ compensation points increased again during senescence, peaking at 5.3 ± 0.8 nmol NH₃ mol^?1 air for cv. Laevigatum. The modern and high-yielding cv. Golf had significantly higher (P < 0.01) NH₃ compensation points than the old and primitive cv. Laevigatum. Golf also had higher shoot NH₄⁺ and total nitrogen concentrations than Laevigatum. During generative growth the ratio between NH₃ and water vapour conductivities increased 10-fold, suggesting a shortening of the diffusive path length for NH₃ compared to H₂O during leaf senescence.     

Histological analysis of somatic embryogenesis in Brazilian cultivars of barley, Hordeum vulgare vulgare, Poaceae

 Histological analysis was performed aimed at elucidating the origin and the developmental process of somatic embryos of two Brazilian cultivars of barley (Hordeum vulgare vulgare), 'MN-599' and 'A-05'. The observed site of somatic embryo origin (SSEO) could originate from a superficial callus cell, possibly indicating a unicellular origin, or from epidermal and subepidermal callus cells, representing a multicellular origin. A fold, the somatic embryo scutellum that subsequently develops into a cotyledonary leaf, indicates the somatic embryo differentiation. The somatic embryos also showed a growth increase of the primary root and, occasionally, a delay in root development. A possible alternative pathway for the origin of somatic embryos is suggested, in which a SSEO forms a clump of somatic embryos. Received: 4 June 1998 / Revision received: 28 August 1998 / Accepted: 7 December 1998     

Production of gynogenic haploids of Hordeum vulgare L.

Haploid plants were regenerated from cultured unfertilized ovaries of Hordeum vulgare L. (barley). Optimal response was obtained by the addition of 0.6 M 4-chloro-2-methylphenoxyacetic acid (MCPA), 2.8 M indole-3-acetic acid (IAA) and 4.4 M 6-benzyladenine (BA) in the N₆ medium. Further increase in the rate of callus formation and the number of green plants produced was possible with the addition of 90 g/l sucrose and 100 g/l coconut water. The stage of development of the ovaries at the time of culture was critical; the largest number of plants being produced by ovaries from flowers at the trinucleate stage of pollen.Abbreviations (BA) 6-benzyladenine - (MCPA) 4-chloro-2-methylphenoxyaceticacid - (2,4-D) 2,4-dichlorophenoxyaceticacid - (GA₃) gibberellic acid - (IAA) indole-3-acetic acid     

Electroporation-mediated transient gene expression in isolated scutella of Hordeum vulgare

Electroporation was used to introduce DNA into excised scutella of immature embryos of Hordeum vulgare L. cvs Golden Promise and Delita. Using the firefly luciferase gene as reporter, parameters were analyzed for high transient gene expression while maintaining tissue viability. Enzymatic wounding was necessary for DNA uptake. The optimized protocol involves use of linearized DNA and addition of 15% (w/v) polyethylene glycol at a field strength of 950 V cm⁻¹ and approximately 56 ms pulse length. A one-day preculture was required for obtaining callus after electroporation. Transient gene expression was further demonstrated using the β-glucuronidase gene. Blue spots were detected at the abaxial scutellar surface, indicating that cells competent for somatic embryogenesis are also amenable to transfection by electroporation.     

真菌发育过程中的蓝光诱导

本文对多种真菌在发育过程中受蓝光诱导的现象进行了综述。蓝光可以诱导多种真菌的形态发生和发育,包括孢子的产生和菌丝的延伸等。此外,蓝光还可引起真菌的生理和生化改变,如细胞膜对离子的通透性的变化、类胡萝卜素的合成等。真菌也存在一个蓝光信号系统,通过蓝光受体接受蓝光信号,导致了真菌的一系列形态发生和生理生化的变化。