Plantago Media Research Articles

Patch Clamp Studies on Root Cell Vacuoles of a Salt-Tolerant and a Salt-Sensitive Plantago Species

Plantago media L. and Plantago maritima L. differ in their strategy toward salt stress, a major difference being the uptake and distribution of ions. Patch clamp techniques were applied to root cell vacuoles to study the tonoplast channel characteristics. In both species the major channel found was a 60 to 70 picosiemens channel with a low ion selectivity. The conductance of this channel for Na(+) was the same as for K(+), P(K) (+)/P(Na) (+) = 1, whereas the cation/anion selectivity (P(K) (+)/P(c1) (-)) was about 5. Gating characteristics were voltage and calcium dependent. An additional smaller channel of 25 picosiemens was present in P. maritima. In the whole vacuole configuration, the summation of the single channel currents resulted in slowly activated inward currents (t((1/2)) = 1.2 second). Inwardly directed, ATP-dependent currents could be measured against a DeltapH gradient of 1.5 units over the tonoplast. This observation strongly indicated the physiological intactness of the used vacuoles. The open probability of the tonoplast channels dramatically decreased when plants were grown on NaCl, although single channel conductance and selectivity were not altered.

Iridoids from Plantago media

The new iridoid 10-acetylmonomelittoside and the known iridoid glucosides aucubin and monomelittoside were isolated from fresh leaves of two varieties of Plantago media. This is the first isolation of monomelittoside from Plantaginaceae.

Trans-Root Electrical Potential in Roots of <italic>Plantago media</italic> L. as Affected by Hydrostatic Pressure: The Induction of an O<sub>2</sub> Deficient Root Core

Excised roots of Plantago media L. were subjected to small hydrostatic pressure gradients. Pressure applied with a displacement pump easily extracted gas present in cortical lacunae consequent on the gas saturation deficit of the bathing solution. The temporary pressure treatment resulted in an irreversible decrease in the O2 diffusion rate through the root tissue and consequently in O2 deficient root cores. Therefore electrogenic pumps located at the symplast/xylem interface, i.e. in the centre of the root, were inhibited by pressure. The longitudinal distribution of the xylem pumps could be computed: in Plantago media they are located in the basal parts of the root. The effect of pressure on the electrogenic xylem pumps demonstrated here should be taken into account when the process of ion transport from the root to the shoot is studied while the root is pressurized.

Bi-phasic composition of trans-root electrical potential in roots of Plantago species: involvement of spatially separated electrogenic pumps

The effect of oxygen on the trans-root potential (TRP) of excised roots in Plantago media L. and P. maritima L. was investigated. Two distinct reactions were found. In some experiments (type A roots) the reaction of TRP to anoxia was bi-phasic, and this reaction fits well into a model, assuming the presence of two spatially separated proton pump sites in the roots: one at the plasmalemma of epidermal and cortical cells and the other at the symplast/xylem interface. The two pumps work in opposite directions. In other experiments (type B roots) no hyperpolarization as a response to anoxia at the inner symplast membrane was observed. There is evidence that the inner pump is also present in these roots, but only in an inactive or electroneutral state. It is concluded that O2-deficiency prevails more often in the central part of the root than in epidermal and cortical cells, when roots are brought gradually under anoxia. This causes the pump located at the symplast/xylem interface to be inhibited more quickly than the other at decreasing O2-concentrations in the bathing solution.

Occurrence of melittoside in the seeds of Plantago media

The 13C NMR and 360 MHz 1H NMR signals of melittoside and its acetate have been assigned.

The effect of salinity on lipid composition and on activity of Ca2+‐ and Mg2+‐stimulated ATPases in salt‐sensitive and salt‐tolerant Plantago species

AbstractLipid composition of the roots and the shoot of the salt‐sensitive Plantago media L., the salt‐tolerant P. maritima L. and the less salt‐tolerant P. coronopus L. was followed under saline conditions. In the roots of P. media the level of phospho‐, galacto‐ and sulpholipids decreased strongly with increased NaCl concentration, indicating decreased control of permeability of the root cell membranes. In the roots of the two salt‐tolerant species the level of most lipid classes was maintained or even raised up to 75 mM NaCl, and a decrease was noted only at higher NaCl concentrations. In P. maritima, a species from relatively nutrient‐rich habitats, decreased lipid levels in the roots and shoot were observed with increasing salinity in combination with a low nutrient availability. The Ca2+‐ and Mg2+‐stimulated ATPase activities of the microsomal fraction of the roots of P. maritima was decreased at a salinity level in excess of 150 mM, while in P. coronopus they were decreased at all NaCl levels tested. The obtained results are discussed as part of the adaptation of the species to salinity.

The Effect of Salinity on Growth, Cation Content, Na+‐Uptake and Translocation in Salt‐Sensitive and Salt‐Tolerant Plantago Species

AbstractGrowth of salt‐sensitive Plantago media L. and salt‐tolerant P. coronopus L. and P. maritima L. was followed under saline conditions. Growth was reduced according to the ecological features of these species: P. media was sensitive to 25 mM NaCl, while P, coronopus and P. maritima could grow in 150 mM and 300 mM NaCl, respectively. The three Plantago species accumulated Na+ in the shoot and maintained a relatively low Na+ level in the root. K+. Mg2+ and Ca2+ levels of both shoots and roots decreased with increasing salinity. The results suggest that the difference between salt‐resistant and salt‐sensitive species is located in the ion secretory system which is involved in the ion translocation from the root to the shoot rather than in the primary uptake process through the plasmalemma of the cortical cells.

Ca2+ and Mg2+‐Stimulated ATPases from Roots of Plantago lanceolata, Plantago media and Plantago coronopus: Response to Alterations of the Level of Mineral Nutrition and Ecological Significance

AbstractGrowth of Plantago lanceolata L., P. media L. and P. coronopus L. was followed at two levels of mineral nutrition (low‐salt and high‐salt). In addition the response of transfer of plants from low‐salt conditions to high‐salt conditions and vice versa was studied. Growth of these Plantago species was not much affected by the nutritional level. P. coronopus showed the least dependence on the level of mineral nutrition.The Ca2+‐ and Mg2+‐stimulated ATPase activity of microsomal preparations of the roots of Plantago was also studied. A pH optimum at pH 6.5 was observed in all species, together with a relatively high ATPase activation by Mg2+ in P. lanceolata, by Ca2+ in P. media, and by both ions in P. coronopus. The specific activity of the ATPases was highest in preparations from low‐salt roots.The three species all occur in relatively nutrient‐poor habitats, but they are at the same time particularly adapted to circumneutral soils (P. lanceolata), to Ca2+‐rich soils (P. media) and to alternating levels of mineral nutrition (P. coronopus). The properties of the ATPases (Km, Vmax, protein content) and the growth are discussed in relation to these ecological properties of the species.

Lipid Composition of the Roots of Plantago Species: Response to Alteration of the Level of Mineral Nutrition and Ecological Significance

AbstractIn a study of the adaptation of Plantago species to their specific environment the lipid composition of the roots of several species: Plantago major L. ssp. major, Plantago major L. ssp. pleiosperma Pilger, Plantago lanceolata L., Plantago media L., Plantago maritima L., Plantago coronopus L. was studied as well as the effect of the nutritional regime. Upon exposure to low‐salt conditions Plantago major L. ssp. major L. and Plantago maritima L. maintained the level of free sterols in the roots, despite a depressed level of total sterols, and the root lipids were more saturated than under high‐salt conditions. Both factors may reduce nutrient leakage from the roots to the low‐salt condition. Upon exposure to low‐salt conditions, all Plantago species showed a decreased level of galactolipid (exception: Plantago coronopus) and a decreased level of sitosterol (exception: Plantago maritima); the latter being compensated by an elevated level of cholesterol + tocopherol in Plantago major ssp. pleiosperma, Plantago lanceolata and Plantago media. Plantago coronopus was the only species which under low‐salt conditions showed an increased level of free sterols, among which cholesterol was the most important; thus indicating a high degree of regulation of membrane permeability under alternating nutritional conditions. The level of sulfolipid was kept constant in all Plantago species, with the highest level observed in Plantago maritima. The role which various lipids may play in maintenance of membrane integrity under alternating nutritional conditions is discussed.

ANTHECOLOGICAL RELATIONS BETWEEN REPUTEDLY ANEMOPHILOUS FLOWERS AND SYRPHID FLIES. II. PLANTAGO MEDIA L.

SUMMARY After intensive field work in Upper Hessia (W. Germany) the authors have come to the conclusion that although Plantago media L. is most probably visited much more frequently and by a wider range of insects than P. lanceolata L., syrphid flies of the Melanostoma-Platycheirus group play a negligible role in the pollen transfer of P. media. The possible reason for this unexpected result is anything but clear and only a tentative possibility is suggested.

Grauballemandens fundsted

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