摘要:

AbstractThe genusPhaseolusis characterized by a highly stable karyotype of 2n = 22. Despite this constancy, the size of the chromosomes varies, and crossing of species is possible only in a few cases. We determined the 2C nuclear DNA content of a number ofPhaseolusspecies, cultivars and genotypes by flow cytometry, in order to realize the interspecific and intraspecific variation of the 2C value. The data range from 1.03 pg to 2.18 pg without any clear correlation to systematic relationships. The mean DNA values of wild and cultivated forms, as well as those of Andean and Mesoamerican genotypes, do not differ significantly. The variation is interpreted in terms of some nucleotypic adaptations. The data may be useful for molecular biological analyses, as well as for biotechnological and classical breeding programmes.

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00513.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractInArabidopsis thaliana, as in other Brassicaceae species, a progressive drought stress induced changes in root morphogenesis: from a threshold plant water deficit, the new emerging roots remain short, hairless and often take a tuberized shape at their base while drought persists. The organization of these drought‐induced roots was examined in light microscopy inArabidopsis thaliana, Columbia wild‐type ecotype, and compared to the normal, well‐watered lateral roots. The main structural traits were the absence of elongation zone, the arrest of cell cap expansion, the lack of root hairs (despite epidermal differentiation in trichoblasts and atrichoblasts) and the radial enlargement of epidermal and cortical cells. The early differentiation, close to the short root apex, of large and highly lignified metaxylem elements, the absence of starch accumulation in hypertrophied cortical cells appeared to be characteristic of the speciesArabidopsis, as compared to other Brassicaceae. These structural alterations are discussed in terms of drought‐induced changes in gene expression with regard to similar modifications described in root morphogenesis and root hair‐defectiveArabidops

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00514.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractReaction norms of fourteen life history and morphological traits were investigated in four tetra‐ and two hexaploid genotypes of the annual weed species complex,Polygonum aviculare. The plants were cultivated in six treatments consisting of factorial combinations of three pot sizes and two fertility levels. All characters, except life span, were plastic but the relative importance of genotype (G), treatment (T) and interaction (G × T) to total variance was strongly trait‐specific. Consistent genetic differentiation, not correlated with ploidy level, was found in metamer size and life history: genotypes originating from trampled sites had smaller metamers and shorter shoots while those originating from sites with a short growing season, due to weeding activities, had a shorter life span, an earlier flowering date and a higher biomass allocation to reproduction compared to genotypes from less disturbed sites. Significant variation was found in reaction norms for all characters, including a lower amount of plasticity in metamer size in genotypes with numerous metamers and a lower amount of plasticity in total weight in shortlived genotypes. This suggested that variation in phenotypic plasticity reflected developmental constraints imposed by contrasting life span and metamer size in different genotypes. There was no evidence for niche differentiation along the soil resource gradient, suggesting that the species is comprised of “general purpose” genotypes with respect to soil fertility. It is concluded that thePolygonum avicularecomplex has evolved a “dual” adaptive strategy i.e. a combination of genetic polymorphism and high phenotypi

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00515.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractCloning and characterization of a barley gene namedemipis reported that encodes a member of the major intrinsic protein family. A λ‐unizap cDNA library synthesized from poly A+−mRNA of leaf epidermis was screened differentially with epidermis‐versus mesophyll‐derived probes. One of the clones epi 3‐2 was sequenced and further analyzed. The open reading frame of the full length clone codes for a polypeptide of 288 amino acids with a molecular mass of 30,634 Da exhibiting a high degree of homology with members of the major intrinsic protein family. Hydropathy analysis predicts six potential membrane‐spanning helices. mRNA levels were high in the growing zone of barley leaves and declined towards the tip of the fully expanded leaf blade. Expression was high in epidermal strips, lower in roots and very low in the leaf mesophyll. In order of decreasing response, wilting, salt shock and heat shock resulted in stimulated expression. mRNA levels remained low during slow salting up experiments. The expressional pattern suggests a role ofEMIPin turgor regulation, particularly

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00516.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractA decreased utilization of NADPH for CO2fixation as a result of carbohydrate accumulation in chlorotic leaves is generally believed to be associated with an increase in oxidative stress. Molecular oxygen may serve as an alternative electron acceptor of photosynthesis under these conditions. In order to test this hypothesis mature leaves of tobacco plants (Nicotiana tabacum) were detached, fed with glucose (50 mM)viathe petiole, and used to study the effect of carbohydrate accumulation on the pigment content and the components of the superoxide dismutase‐ascorbate‐glutathione cycle. During a period of five days the concentration of total soluble carbohydrates increased substantially in leaves supplied with glucose in comparison with control leaves supplied only with water. This increase was accompanied by a twofold decrease in the chlorophyll content. In detached water‐fed leaves the levels of most of the antioxidative components increased, whereas glucose feeding had no or only little additional effect on the activities of the protective enzymes, but caused a 1.6‐ and 4‐fold increase in the contents of glutathione and ascorbate, respectively. In relation to the total foliar ascorbate pool, the amount of reduced ascorbate increased from about 30 % to 60 % upon feeding with glucose. These results do not support the idea that the accumulation carbohydratesper secause an increased rate of superoxide production which necessitates increased activities of antioxidative enzymes. It rather appears that glucose‐fed leaves have an increased reductive capacity that can be releasedviaglutathione into the ascorbate pool, thereby, regulating the redox state o

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00517.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractCellular and subcellular volumes in mature leaves of potato (Solanum tuberosumcv. Désirée) were determined stereologically from light and electron micrographs. Leaves of ten‐week‐old plants with a total leaf volume of 623 μL per mg chlorophyll (Chl) were found to be composed of 12 % epidermis, 68 % mesophyll, 5 % vascular tissue, 3 % apoplast and 16 % gas space. In the epidermal cells 97 % of the volume was occupied by the vacuole. The mesophyll cells consisted (as expressed per mg Chl) of 323 μL (76 %) vacuole, 35 μL (8 %) chloroplast stroma, 22 μL (5 %) cytosol plus nucleus and peroxisomes, and 4μL, (1 %) mitochondria. A comparison of these values with subcellular volumes previously determined for spinach and barley leaves, shows that the relative sizes of the subcellular volumes are strikingly similar. Subcellular concentrations of carbohydrates, of the phosphorylated intermediates of carbohydrate metabolism, of malate, and of amino acids have been evaluated from measurements of the corresponding subcellular metabolite contents determined using the non‐aqueous fractionation technique. Malate, glucose and fructose were found to accumulate in the vacuole, whereas the concentration of sucrose and amino acids in the cytosol were much higher than in the vacuole. The amino acid concentration in the chloroplast stroma is similar to that in the cytosol. Phosphorylated intermediates of carbohydrate metabolism are confined to the chloroplast stroma and the cytosol, confirming the validity of the fractionation method. Whereas triose phosphates and fructose‐l,6‐bisphosphate are concentrated in the stroma, the concentrations of hexose monophosphates were highest in the cytosol. Since the subcellular metabolite distribution in potato leaves reported here is very similar to that previously described for spinach and barley leaves, we conclude that it may be characteristic for mesophyll

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00518.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe green alga,Chlamydomonas reinhardtii, was grown under high and low CO2regimes inducing significantly different activities of the extracellular carbonic anhydrase (CA). In close relation to the CA activities, the algae exhibited different consumption rates of the climatically relevant atmospheric trace gas, carbonyl sulphide (COS), thus indicating that CA is responsible for uptake of COS from the medium.

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00519.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe origin of the presumed allopolyploidArabidopsis suecicahas been explored through isozyme electrophoresis and mutational analysis of chloroplast (cp) DNA. Nuclear encoded isozymes are inherited biparentally and were used to indicateA. thalianaandCardaminopsis arenosaas parental species. Analysis of the maternally inherited cpDNA provided strong evidence forA. thalianaas maternal parent. The isozyme data suggest multiple origin ofA. suecica, because the alloploid shows polymorphisms at the same loci that are polymorphic in its progenitors. The molecular data are in agreement with the hypothesized recent origin ofA. suecicaat the Late glacial/Holocene boundary in Fennoscandia, in areas opened up by retreating glaciers.

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00520.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractPrimary root growth dynamics and lateral root development of dark‐ and light grown cotton seedlings (Gossypium hirsutumL., cv. Acala SJ‐2) were studied under control and salinity stress conditions. The seedlings were grown by two methods: A) in paper‐lined, vermiculite‐filled beakers with the plants growing between the paper and the glass wall (Gladish and Rost, 1993), and B) in hydroponics after germination and initial growth in germination paper rolls saturated with the treatment solutions (Kent and Läuchli, 1985). After germination, daily primary root elongation rate gradually incrased to a maximum, then gradually declined to close to zero for dark‐grown seedlings, or to sustained rates of about 10 mm per day for light‐grown control plants. Salinity stress delayed primary root growth and reduced peak elongation rates, without changing the general primary root growth pattern. These results suggest that salinity changed the time‐scale, but did not modify the normal developmental sequence. Lateral root growth was more inhibited by salinity than primary root growth. In addition, elongation of lateral roots was more inhibited by salinity than their initiation and emergence. Light exposure of the shoot favored both sustained primary root growth from 7 days after planting, and lateral root emergence and growth. Salinity effects were more severe on seedlings germinated and grown in hydroponics (method B) than on vermiculite‐grown plants (method A). These results emphasize the importance of growing conditions for the NaCl‐induced effects on cotton root development. In addition, the differential effects of salinity on primary and lateral roots became evident, pointing to diverse control mechanisms for the development o

ISSN:0932-8629    

DOI:10.1111/j.1438-8677.1995.tb00521.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY