Plant Primary Metabolism Research Articles

Foyer, C.H., Quick, W.P.: A Molecular Approach to Primary Metabolism in Higher Plants

Biologia plantarum, an international journal for experimental botany founded in 1959 by Professor Bohumil Němec. Covers all branches of experimental botany ranging from molecular biology and biotechnology to whole-plant and stand functioning.

Study on Tetranychus cinnabarinus-Solanum melongena interaction system II: the relationship between piercing-sucking of T. cinnabarinus and induced changes of PAL and G6PD enzyme activity in S. melongena leaves

Abstract An interactive system made of Solanum melongena L. and Tetranychus cinnabarinus (Boisduval) was used to study the relationship between T. cinnabarinus population dynamics and S. melongena physiological changes in this paper. Continuous measurements of PAL (a key enzyme in propylbenzene metabolism pathway) and G6PD (a representative enzyme in plant primary metabolism) activity shed new light on S. melongena's stress reaction caused by T. cinnabarinus piercing-sucking. Results showed that changes in enzyme activity was correlated with the strength of T. cinnabarinus stress and both were fluctuating during the interaction. It was concluded that the defence of S. melongena when attacked by T. cinnabarinus was an entire stress reaction coordinated by primary and secondary metabolism, and was a self-regulated, fluctuating, normal physiological process.

A molecular approach to primary metabolism in higher plants. Edited by Christine H. Foyer and W. Paul Quick

A molecular approach to primary metabolism in higher plants. Edited by Christine H. Foyer and W. Paul Quick

Response of primary plant metabolism to the N‐source

AbstractEven when plant growth was not visibly affected, ammonium versus nitrate nutrition had distinct effects on some parts of plant metabolism. Barley seedlings growing on 3 mM ammonium rapidly accumulated ammonium up to 20 mM in the roots. In leaves, ammonium accumulation was observed only when the pH of the nutrient medium was very low (pH 4). Yet even under the most extreme conditions there was no indication that plants were suffering from uncoupling of ATP synthesis or from a lack of carbohydrates.Especially dramatic was the response of the organic acid content of pea and barley leaves: it decreased strongly within a few days upon transfer of plants from nitrate to ammonium‐media, and this was apparently not due to an inhibition of PEPcarboxylase, which was rather activated under ammonium nutrition. As malate dispappeared from leaves even when pea plants were transferred to an N‐free medium, malate degradation was not necessarily connected to increased amino acid synthesis, but eventually to a more rapid decarboxylation by malic enzyme. Also, malate degradation was not a response to ammonium, but rather to (the absence of) nitrate.

Primary and Secondary Metabolism of Plants and Plant Cell Cultures III.

Primary and Secondary Metabolism of Plants and Plant Cell Cultures III.

Turnabout is fair play: Secondary roles for primary compounds

Chemically based resistance of plants to herbivorous insects is today essentially synonymous with allelochemically based resistance; the importance of plant secondary compounds in determining patterns of host-plant utilization has been established in a wide variety of insect-plant interactions. In contrast, primary metabolites, those involved in fundamental plant physiological processes, are rarely considered to be major determinants of host-plant resistance despite the fact that, as insect nutrients, they can have profound effects on behavior and physiology. The degree to which variation in plant primary metabolism results from the selective impact of herbivory may be greatly underestimated in that the biosynthetic and structural diversity of primary metabolites and the consequences of that diversity on herbivores are rarely taken into account in most studies of insect preference and performance. Qualitative and quantitative variation in the production of primary metabolites can result from herbivore selection pressure if production of primary metabolites is under genetic control and if plant fitness in the presence of herbivores is associated in a predictable way with genetically based primary metabolite variation. Variation in primary metabolism is likely to be particularly effective as a defense against highly oligophagous herbivores with limited mobility, especially those confined to structures containing allelochemicals that could neutralize the benefits associated with compensatory feeding.

Manipulation of carbohydrate partitioning

The reverse genetics approach is allowing the definition of specific reaction steps in plant carbohydrate metabolism. This is enabling the design of studies to alter sucrose and starch partitioning in the leaf, to inhibit phloem transport, or to increase/inhibit the rate of sucrose import into storage organs and its conversion to starch. These studies provide information about what kind of change should be made to biosynthetic pathways to achieve a desired aim. They also highlight the flexibility of plant primary metabolism and reveal a multi-faceted interaction between carbohydrate metabolism and many other aspects of plant growth and development.

Nutrient availability and accumulation of phenolic compounds in the brown alga Fucus vesiculosus

Plant phenols tend to accumulate under conditions where plants have excess carbon above the level which can be used for growth, and where phenylalanine, the substrate of phenylpropanoid synthesis, accumulates due to suppressed protein synthesis. These internal balances imply an accumulation of phenols as a consequence of nitrogen deficiency suppressing plant primary metabolism. In three sublittoral populations of the brown alga Fucus vesiculosus (L.) collected from the northern Baltic Sea between May and September 1982, the accumulation of phenolic compounds correlated inversely with nitrogen content of thallus; higher phenolic contents were on average found under nitrogen deficiency. Phenolic content did not correlate with carbon content of thallus as such, while a significant negative correlation was found with the nitrogen: carbon ratio. Phenolic compounds, although having possibly defensive functions in plants, may thus partially vary as a function of resource availability rather than as a result of an active allocation into plant defences.

Chloroplast metabolism: the pathways of primary carbon metabolism in C3 plants

Chloroplast metabolism: the pathways of primary carbon metabolism in C3 plants

Chloroplast metabolism: the pathways of primary carbon metabolism in C3 plants

Chloroplast metabolism: the pathways of primary carbon metabolism in C3 plants

Oscillations in the Activities of Enzymes of Nitrate Reduction and Ammonia Assimilation in Glycine max and Zea mays

AbstractThe activities of glutamate dehydrogenase (GDH), glutamine synthetase (GS), and nitrate reductase (NR) and the levels of soluble protein and NO‐3 were assayed in soybean (Glycine max [L.] Merr.) leaves over a 48‐h period with the initial 24 h under a light‐dark cycle (LD 16:8) followed by 24 h of continuous light (LL). Plants had been entrained for 30 days under the LD regime. Maize (Zea mays) leaves (10 days old) under a LD 15:9 cycle were assayed only for NR and nitrite reductase (NiR). Data were subjected to frequency analysis by the least squares method to determine probabilities for cosine function periods (τ's) between 10 and 30 h. NR activities for both soybean and Zea leaves had 24 h τ's with P values < 0.05 indicating circadian periodicity. GDH in soybeans had a 24‐h rhythm under LD conditions which lengthened under LL conditions. The 24‐h rhythm of GDH displayed maximal activity toward the end of the dark period of the LD cycle whereas the highest activity of NR was early in the light period. Total soluble protein displayed a rhythm with a best fitting τ of greater than 24 h under both LD and LL. GDH, GS, NR, NO3, and soluble protein in soybeans and NiR in Zea, all displayed that were ultradian (10–18 h), indicating that a τ of about one half a circadian periodicity may be a common characteristic of the enzymes of primary nitrogen metabolism in higher plants. These data also demonstrate that although both NR and GDH are circadian in their activity, the 24‐h rhythm may be greatly influenced by ultradian oscillations in activity.

Einfluß verschiedener flavonole auf das lamellarsystem der chloroplasten in vitro

The influence of various flavonoles on light triggered reactions of isolated chloroplasts was examined in order to receive some more detailed information about the problem just in discussion, wether those substances of the secondary metabolism are involved in reactions of primary metabolism of plants. Among the substances examined kaempferol was the most active one. 1. ATP synthesis is inhibited by kaempferol at a concentration of about 8 · 10 −5 M. Inhibition is due to an influence on the chloroplast membrane itself. 2. Calcium dependent, trypsin activated ATPase is stimulated at the mentioned concentration range, whereas magnesium dependent light triggered ATPase is inhibited as cyclic photophosphorylation too. 3. Electron transfer, measured with various Hill-reagents, is neither inhibited severely nor stimulated. 4. Kaempferol inhibits the methylamine uncoupled electron transfer up to 40 0/o. These results suggest that kaempferol does not act as an energy transfer inhibitor according to Good. Though kaempferol does not stimulate electron transport, it is assumed that kaempferol acts more like an uncoupling substance influencing a reaction site near electron transport chain, preventing the energy transfer from electron transport chain to ATPase. 5. Bovine serum albumine prevents the kaempferol inhibition up to 50%, if it is adjected to the medium before kaempferol. Polyvinylpyrrolidon, which is an usefull reactivator of tannin inhibited reactions, does not reactivate kaempferol inhibited membrane bound enzyme reactions. 6. Flavonole glucosides inhibit pseudocyclic photophosphorylation at the same concentration range up to 40 %. From these results it is concluded, that a part of the measurable kaempferol inhibition is due to a more specific reaction, whereas a second part seems to be due to an unspecific reaction between a protein and kaempferol. Nevertheless it is clear that flavonoles do have an influence on the primary metabolism of chloroplasts. But it seems to be impossible to postulate a corresponding effect of flavonoles in vivo, since kaempferol was not found in spinach chloroplasts.