Otília Gašparíková

Biochemical and Physiological Aspects of Developmental Cycle of Colchicum autumnale L.

This study was conducted to examine the individual developmental stages of Colchicum autumnale. We identified the sclerenchymatic tissue in the middle part of the protuberance. This tissue supports the function of protuberance as a kind of hollow diverticulum. On the boundary of the new corm and the shoot a meristematic layer was recognized. We assume that this abscission zone-like structure can initiate dying back of the above-ground part regularly at the end of annual life-cycle. The major part of starch is reutilized in the mother corm during the autumnal stage, supporting sprouting which takes place in the soil. Decline of starch content is paralleled by increasing of total amylolytic activity. From amylolytic enzymes α-amylase, β-amylase and α-glucosidase have been identified. The presence of pullulanase and starch phosphorylase was not observed. From free sugars glucose, fructose and sucrose were identified in corms. The level of sucrose increased significantly during winter season.

Recent Advances of Plant Root Structure and Function

Preface. I: Structural and Molecular Aspects of Root Growth and Development. Histochemical analysis of root meristem activity in Arabidopsis thaliana using a cyclin:GUS (beta-glucuronidase) marker line M.-T. Hauser, E. Bauer. Ultrastructural effects of the herbicide chlorpropham (CIPC) in root tip cells of wheat E.P. Eleftheriou, E. Bekiari. Measurement of viscoelastic properties of root cell walls affected by low pH in lateral roots of Pisum sativum L. E. Tanimoto, et al. Secondary dilatation growth in the root endodermis A. Lux, M. Luxova. Changes of root structure in connection with the development of lateral root primordia in wheat and pumpkins K.N. Demchenko, N.P. Demchenko. Some aspects of endodermis and cortex structure in Dryas roots K.M. Barmicheva, M.F. Danilova. IAA and ZR content in leek (Allium porrum L.), as influenced by P nutrition and arbuscular mycorrhizae, in relation to plant development A. Torelli, et al. Polyploidy in tomato roots as affected by arbuscular mycorrhizal colonization G. Berta, et al. II: Physiology of Water and Ion Uptake. Water uptake by plant roots: an integration of views E. Steudle. Root-shoot interactions in mineral nutrition W.D. Jeschke, W. Hartung. Calcium channels in the plasma membrane of root cells: Their roles in mineral nutrition and cell signalling P.J. White, M.S. Ridout. Nitrogen and base cation uptake in seedlings of Acer pseudoplatanus and Calamagrostis villosa exposed to an acidified environment V. Gloser, J. Gloser. Nitrate uptake by bean (Phaseolus vulgaris L.) roots under phosphate deficiency A. Gniazdowska, A.M. Rychter.Nitrate reductase in roots: Succinate- and NADH-dependent plasma membrane-bound forms C. Stohr, et al. Impact of Agrobacterium tumefaciens-induced stem tumors on NO--3 uptake in Ricinus communis I. Mistrik, et al. Fast shoot responses to root treatment. Are hormones involved? G. Kudoyarova, et al. III: Root under Stress Conditions. Response of tomato plants to chilling stress in association with nutrient or phosphorus starvation Z. Starck, et al. Effect of water stress upon root meristems of pea seedlings: The role of quantitative and qualitative changes in protein patterns D. Chiatante, et al. The distribution of lead in duckweed (Lemna minor L.) root tip S. Samardakiewicz, A. Wozny. Lead effects on cereal roots in terms of cell growth, root architecture and metal accumulation N.V. Obroucheva, et al. Diverse responses of root cell structure to aluminium stress M. Ciamporova. Relationship between microtubule orientation and patterns of cell expansion in developing cortical cells of Lemna minor roots S. Inada, S. Sato.

Protein reutilisation in corms of Colchicum autumnale

Colchicum autumnale L. is a monocotyledonous geophyte with hysteranthous leaves, i.e. flowering and leaf growth occur in different time periods. Because after the starch, the second prominent storage compound of corm is represented by proteins, we were interested in nitrogen remobilisation during the annual life cycle of C. autumnale. In this context the content of soluble and insoluble proteins were measured in parallel with determination of some exo-and endopeptidase activities. Our results indicate that the continual proteolysis occurs in both mother and new daughter corms during the whole life-cycle of the plant. L-Ala-aminopeptidase and trypsin-like endopeptidase were the most active peptidases in both mother and daughter corms. As the protein level of mother corm did not change significantly during the development of the future above-ground part under the soil surface (the first, autumnal developmental stage), the developmental profile of nitrate reductase activity was estimated followed by evaluation of total nitrogen and amino acid contents. Significant activity of root nitrate reductase was detected in the roots only in the second, vernal stage. Our results showed that the stored proteins constituted a relevant nitrogen source partly required by the growth processes of the late autumnal stage, but mainly by the intensive growth of leaves and reproductive structures during the second, photosynthetically active stage of the life-cycle.

Nitrate reductase, nitrite reductase and glutamate dehydrogenase levels in roots and leaves of maize seedlings

Total activities of nitrate and nitrite reductases were higher in 4 to 20 day old maize plants in the leaves than in the roots. The ratio of activities found in the leaves and in the roots respectively was much higher in the case of nitrate reductase than in the case of nitrite reductase. On the other hand higher glutamate dehydrogenase activity in the roots than in the leaves clearly indicates that the roots play a more important role in the assimilation of ammonium than in the assimilation of nitrate. When comparing the distribution of seminal and nodal adventitious roots of maize seedlings with the assimilation of inorganic nitrogen on the basis of enzyme levels, it could be deduced that during the first 20 days of seedling growth seminal roots were more involved in the assimilation of nitrate whereas nodal adventitious roots were more active in ammonium assimilation.

Activity and polymorphism of enzymes in different root tissues

The manner in which cells of higher organisms acquire structural and functional specificity during differentiation and development is of general biological interest. Most authors assume differential gene expression and the level of regulation would be either at the gene, or in the pathway between the gene and its final product, the functional enzyme. One approach to the problem is to study the ontogeny of enzymes characteristic of a particular system since this provides a sensitive index of the basic changes occuring during differentiation. Therefore, enzyme activities, protein and isoenzyme patterns in different root regions have been compared many times (Benes and Hadacova, 1988; Benes et al., 1981; Hadacova and Benes, 1977; Khavkin, 1977; Obrucheva, 1975; Polter and Muller-Stoll, 1969; Steward et al., 1965; Sutcliffe and Sexton, 1974). The available quantitative evidence in some cases relates to metabolic gradients from the apex to the mature root cells.

Cold-Induced Alterations in Protein Composition of Maize Roots

There is mounting evidence to indicate that most cold tolerant plant species synthesize new sets of proteins that are correlated with the increase in cold hardiness (Howarth and Ougham, 1993). Some of the surveys suggests the possibe role of protein synthesis also in chilling tolerance in plant species native to tropical or subtropical habitats (Xin and Li, 1993). However, the data are scarce. Therefore, the objective of this study was to identify soluble and microsomal membrane proteins that are specifically induced by chilling and examine activity and isozymic composition of such enzymes in maize roots. Primary roots of two genotypes, chilling-sensitive Penjalinan and chilling-tolerant Z7, were used. Seedlings were grown on Hoagland’s nutrient solution, in a growth chamber, at 24°C, 70% relative humidity and 12 h photoperiod, until the third leaf stage. Then plants were subjected to a 5 days stress period at 6°C, followed by a 4 days recovery at 24°C. Control plants were maintained at 24°C for the whole period. Protein extraction, SDS-PAGE and detection were carried out as described previously (Gasparikova et al., 1996).

Changes in respiration and ultrastructure of radicle mitochondria during early germination in isolated wheat embryos

The contributions of the cytochrome and alternative pathways to total respiration were assessed together with mitochondrial structure during the early stages of germination of isolated wheat embryos (Triticum durum, cv. Appulo). Sharp acceleration in oxygen uptake occurred within minutes after the embryos had been exposed to water. The initial increase in total dark respiration was due to an increase in the activity of the cytochrome pathway. The presence of the alternative pathway was observed from 0.5 h to 3 h and later. The capacity of alternative pathway progresively increased during germination, amounting to 70 percent of the control rate of respiration after 24 h. However, its involvement was rather low at 24 h after imbibition. The development of mitochondrial structure during this period indicated that the initial acceleration of O2 uptake resulted from the activation of pre-existing mitochondria and by an increase in the number of cristae per mitochondrion. An increase in the relative number of mitochondria and in the number of cristae per mitochondrial cross section was responsible for the next increase of O2 uptake between 6 and 24 h. There was not a continuous increase in the formation of mitochondrial cristae or in the relative number and volume of mitochondria in the cortical cells of radicle during the first 24 h of germination of the isolated wheat embryos. Similarly, the total rate of respiration as well as the activities of the cytochrome and alternative pathways increased more rapidly in the early stages than after 6 h of imbibition.

Section 4 - Root physiology and plant structure

Explants from single trees of Abies concolor (Gord. et Glend) Lindl. • Abies grandis (mature embryo), Quercus robur L. (embryonic axis, young stem segments), Quercus rubra L. (young stem segments) and Castanea sativa L. (embryonic axis of mature embryo) were cultured on a callusinducing medium with NAb, or IBA (in Castanea) and BAP. Differentiation of tracheids tn both callus and explant tissues was preceeded by formation of cambium-like cells forming wound procambium zones of different shape. These zones produced tracheidal cells either on their convex side (cambium near to callus surface) or concave side (virtually wound cambium zones), where tracheid nests were produced. These were composed of irregulary arranged short or long and wound tracbeids surrounded by cells of the wound cambium. Tracheid nests originated in callus produced on hypocotyl-radicula region ofAbies explants were composed of nodal tracheids irregular in shape surrounded by the layer of the meristematic cells isodiametric in shape, capable of differentiation into tracheid cells. These tracheids as well as others differentiated in Abies explants had thickened secondary side walls with large circular bordered pits and sometimes, in addition, wound helical thickenings. On the other hand, in tracheids differentiated in callus of Quercus sp. and Castanea small circular or oval non-bordered pits or step-like thickening of secondary wail prevailed.

Effect of the Nitrate Level on Growth and Some Aspects of Energy Metabolism in Maize Roots

ABSTRACT The effects of different nitrate applications on growth and various aspects of energy metabolism, including photosynthesis, root respiration and the proportion of the SHAM-sensitive alternative pathway were studied. The accumulation of soluble carbohydrates and nitrates in roots and shoots were also determined in young plants of Zea mays L. Plants were grown in a controlled environment chamber in balanced nutrient solutions containing 0.4, 3.5, 40 or 60 mmol. 1- 1 NO 3 – . The total plant growth rate was only slightly affected by the level of NO 3 – but a reduction in the leaf area and also in root length with increasing KNO 3 concentrations led to a progressive increase in specific leaf (SLW) and root weight (SRW). It appears that, under these conditions, the utilization of assimilates and NO 3 – absorbed in growth processes decreases. Higher levels of non-structural carbohydrates and nitrates in both shoots and roots confirmed this. NO 3 – treatment substantially altered the partitioning of dry matter within the root system. The differences in the degree of growth inhibition among the seminal and nodal roots are discussed. The respiration rate of roots increased with increasing NO 3 – concentration. At 40 mmol.1 –4 NO 3 – , this increase was nearly fully proportional to the increase in SHAM-sensitive alternative pathway. However, these roots accumulate enough soluble carbohydrates to provide an osmotic adjustment of root cells in response to a low water potential in the nutrient solution caused by the high concentration of NO 3 – . Possible explanations for the differences in NO 3 – accumulation are also discussed.

The response of Zea mays roots to chilling

The hardiness of plants in withstanding chilling temperatures has captivated the interest not only of those concerned in theoretical research but of others involved in agronomical practice. While in plant breeding considerable attention has been paid to the temperate zone in order to obtain resistant cultivars, investigation into the biological principles of cold and frost resistance has been on the rise for only the last 10–15 years.