Phosphorus-deficient Conditions Research Articles

Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. II. Phytoplankton species composition

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 18:55-65 (1999) - doi:10.3354/ame018055 Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. II. Phytoplankton species composition Per Carlsson*, Edna Granéli University of Kalmar, Department of Marine Sciences, POB 905, S-391 29 Kalmar, Sweden *E-mail: per.carlsson@ng.hik.se ABSTRACT: Development of phytoplankton biomass and species composition in northern Adriatic Sea natural plankton communities was investigated in 2 spring/summer (May and June) enclosure experiments. The enclosures (100 l plastic cylinders) were subjected to different concentrations/ratios of nitrate, phosphate and silicate in order to obtain a situation where one of these nutrients would limit phytoplankton biomass in different treatments. The initial phytoplankton community in both experiments was dominated by small (both by cell numbers and biomass) autotrophic flagellates. In the May experiment the small autotrophic flagellates made up more than 50% of the initial biomass; this was 95% in June. The duration of the experiments were 7 and 10 d, respectively. A surplus of nitrogen, phosphorus and silicon favored the development of some fast-growing diatoms. Phosphorus deficiency induced higher phytoplankton biomass than expected from Redfield ratios (Redfield 1958), probably due to fast recycling of phosphorus compared to nitrogen. Despite low silicon concentrations in the silicon-deficient treatments, growth of diatoms was high in the May experiment suggesting a low silicon demand for the dominating small diatom species. The diatom Rhizosolenia fragilissima was particularly favored under phosphorus-deficient conditions whereas under nitrogen deficiency another diatom (Chaetoceros sp.) increased in biomass. Small flagellates were favored by either nitrogen deficiency (May) or by silicon deficiency (June). The increasing dominance of small flagellates in the natural communities during the transition from spring to summer, together with decreasing concentration of inorganic nitrogen, indicates that shortage of inorganic nitrogen can be important for the structure of northern Adriatic phytoplankton communities in this period. KEY WORDS: Adriatic Sea · Phytoplankton species composition · Diatoms · Flagellates Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 18, No. 1. Publication date: July 16, 1999 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1999 Inter-Research.

An Arabidopsis mutant missing one acid phosphatase isoform.

Plant response to phosphorus starvation includes the increased production and secretion of acid phosphatase. We have isolated a mutant of Arabidopsis thaliana (L.) Heynh., phosphatase-underproducer 1 (pup1), that has reduced histochemical staining for acid phosphatase activity in roots of plants grown under phosphorus-starvation conditions. Although pup1 is defective in the production of one inducible acid phosphatase isoform, the most abundant inducible isoform is present. The pup1 mutants are able to respond to phosphorus-deficient conditions by an increase in overall levels of acid phosphatase activity, accumulation of anthocyanins, an increase of the root-to-shoot ratio, and changes in the partitioning of phosphorus between roots and shoots. The gross morphology of the mutants appears normal, except that a small difference in the root to shoot ratio was observed in plants grown under nonstressed conditions. The pup1 gene is incompletely dominant and it is located between 40.2 (+/- 6.2) and 44.9 (+/- 9.9) cM on chromosome 2. This mutant will be useful for determining the role of this acid phosphatase isoform in plant response to phosphorus starvation.

Purification and characterization of phytase induced in tomato roots under phosphorus-deficient conditions

Phytase (myo-inositol hexakisphosphate phosphohydrolase; EC 3.1.3.8) was purified from roots of tomato plants grown under phosphorus-deficient conditions using five purification schemes. The phytase was successfully separated from the major acid phosphatase to an electrophoretic homogeneity. The native molecular weight of this enzyme was estimated to be about 164 kD by Bio-Gel P-200 gel filtration. The molecular weight of the subunit on SDS-PAGE was approximately 82 kD, indicating that the native form of the enzyme was a homodimer. The isoelectric point of tomato phytase was about 5.5. The enzyme exhibited a high affinity for phytic acid (K m = 38 μM), and was strongly inhibited by phosphate, molybdate and fluoride. Among other characteristics of tomato phytase, the pH and temperature optima were 4.3 and 45°C, respectively. Tomato phytase contained a fairly high concentration of aspartic, glutamic acid and glycine residues.

Properties of secretory acid phosphatase from lupin roots under phosphorus-deficient conditions

Phosphorus deficiency induces the synthesis of acid phosphatases in roots of lupin and other plant species. In this study we examined the induction of secretory acid phosphatase (S-APase) at both the molecular and cellular levels. Lupin plants had increased levels of total acid phosphatase activity within two to five days after P was withered and levels approximately doubled by 15 days. Lateral roots and not main tap roots were responsible for this increase in acid phosphatase activity. Immunoblot analysis using antibodies raised against a purified S-APase showed that the synthesis of this protein was induced as early as 2 days in the P deficient treatment and that levels dramatically increased by 15 days. In contrast, no immunoreactive polypeptide was evident from crude extracts prepared from root tissues of—P treated plants. Immunocytochemical analysis revealed that the protein was located on the surface of epidermal cells of main tap roots and in the cell walls and intercellular spaces of lateral roots and lateral roots may actively secrete S-APase as soon as it is synthesized. A cDNA clone encoding the S-APase was isolated from a cDNA library constructed from lupin roots grown without P. The clone was 2,187 bp in length and had a single open reading frame of 637 amino acid residues. The deduced amino acid sequence was identical to the N-terminal region and peptide sequences of S-APase purified from lupin roots. A hydrophobic signal peptide region consisted of 31 amino acids. The primary structure was highly homologous to iron-zinc purple acid phosphatase from Phaseolus vulgaris (76%), secretory purple acid phosphatase from Arabidopsis thaliana (71%), and two Aspergillus phosphate repressible acid phosphatases (59% and 58%).

Secretion of phytase from the roots of several plant species under phosphorus-deficient conditions

Phosphorus (P) deficiency increased the secretion of phytases from roots of various plant species. The secretory phytases were collected with a dialysis membrane tube for 24 hours from roots of sixteen plant species grown with low or adequate supply of P in nutrient solutions. The activity of not only secretory phytase, but also acid phosphatase, increased with the low P treatment in all of the plant species examined. Secretion of phytase by the roots under P-deficient conditions was highest in Brachiaria decumbens CIAT 606, Stylosanthes guianensis CIAT 184 and tomato, moderate in Brachiaria brizantha CIAT6780, Stylosanthes guianensis CIAT 2950, alfalfa, white clover and orchard grass, and lowest in Andropgon gayanus CIAT 621, Stylosanthes capitata CIAT 10280, upland rice, timothy, redtop, alsike clover, red clover and white lupin plants. An immunoreactive protein band that reacted with a polyclonal antibody raised against wheat bran phytase, corresponding to molecular weight 35–40 kD, could be detected in seven of the species tested. These results indicate that the secretory phytase may provide an efficient mechanism for certain plants to utilize inositol hexaphosphate in soil.

The effects of ammonium on growth, accumulation of free amino acids and nutritional status of young phosphorus deficient Stratiotes aloides plants

Turions of Stratiotes aloides L. were grown at different ammonium levels under phosphorus deficient conditions in a staged gradient. After 13 weeks the plantlets appeared to be severely phosphorus deficient with the growth being seriously impaired. Nitrogen in the plants appeared to be predominantly present as soluble amino acids. This indicates that net protein synthesis was seriously disturbed. Asparagine was by far the dominant soluble amino acid in the plantlets. At the highest external ammonium levels, net growth was significantly retarded when compared with the other concentrations with free ammonium accumulating in the plants. Ammonium uptake under phosphorus deficient conditions strongly increases nutrient imbalances in the plants, and thus their vitality.

Purification and properties of acid phosphatase secreted from lupin roots under phosphorus-deficiency conditions

Abstract When lupin plants were grown in phosphorus-deficient nutrient solutions, the activity of acid phosphatase secreted from their roots remarkably increased in comparison with that under adequate phosphorus conditions. Based on activity staining of acid phosphatase on IEF gels, many isozymes were present in roots and leaves, but one of these was mainly secreted into the rhizosphere. This main acid phosphatase secreted from roots was purified from the phosphorus-deficient nutrient solution where lupin was grown, using ion exchange chromatography with DEAE-Sepharose CL-6B, gel filtration with Bio-Gel P-200, and preparative-PAGE. The molecular weight of the purified enzyme was estimated to be 72,000 by SDS-PAGE and approximately 140,000 by gel filtration. Thus, this enzyme was considered to be a homo-dimer. The isoelectric point and the optimum pH of the enzyme were 4.7 and 4.3, respectively.

Secretion of acid phosphatase by the roots of crop plants under phosphorus-deficient conditions and some properties of the enzyme secreted by lupin roots

Secretion of acid phosphatase by the roots of crop plants under phosphorus-deficient conditions and some properties of the enzyme secreted by lupin roots

Induction of Soluble Phosphatases under Ionic and Non-ionic Osmotic Stresses in Wheat

Summary The effects of phosphorus deficiency, salt stress (NaCl) and non-ionic osmotic stresses (caused by mannitol or polyethylene glycol) were compared in plants and calli of wheat varieties differing in salt and drought tolerance. In calli, phosphorus deficiency induced a high increase in soluble acid phosphatase activity; under osmotic stress conditions a similar increase was found only in cells subjected to NaCl, while in cells grown in the presence of mannitol, phosphatase activity did not change. In wheat seedlings, phosphatase activity increased both in roots and shoots under phosphorus deficiency and, especially in the shoot, under salt and non-ionic osmotic stresses as well. Contrary to phosphorus deficient conditions, the induction of phosphatase activity under ionic and non-ionic osmotic stresses was not accompanied by a decrease in phosphorus content. These results suggest that the induction of acid phosphatase under osmotic and salt stresses may have a cause other than a low phosphate level. The Mg2+ activated alkaline phosphatase activity specific for the shoot decreased under all stress conditions.

Secretion of acid phosphatase by the roots of several crop species under phosphorus-deficient conditions

Abstract Nine crop species (rice, wheat, soybean, lupin, azuki bean, sugar beet, tomato, cabbage and radish.) were grown in phosphorus-sufficient and phosphorus-deficient nutrient solutions. Then, the activities of acid phosphatase secreted by the roots for 24 h and of that eluted by 100 mM NaCl were investigated. Both activities of acid phosphatase increased under low phosphorus conditions in all the crop species. The activity of acid phosphatase secreted by the roots under phosphorus-deficient conditions was remarkably high in lupin and tomato, high in cabbage and radish, moderate in soybean and sugar beet, and low in wheat and azuki bean. The increased rates of activity of acid phosphatase (on a root dry weight basis) secreted under phosphorus-deficient conditions when compared with those under phosphorus-sufficient conditions ranged from 1.5 times in azuki bean to 19.9 times in lupin. The activity of acid phosphatase in the NaCl eluates was also higher in all the crop species under phosphorus-deficien...

Lack of compensatory growth under phosphorus deficiency in grazing-adapted grasses from the Serengeti Plains.

Two shortgrass species (Sporobolus ioclados and Eustachys paspaloides) and two midgrass species (E. paspaloides and Pennisetum mezianum) from the Serengeti grasslands of Tanzania were grown under conditions of extreme phosphorus (P) deficiency. Production of each of these species is maintained or enhanced by defoliation under adequate nutrient supply (McNaughton et al. 1983). However, under the P-deficient conditions of our experiment, defoliation caused a reduction in biomass of all plant parts of each species. Green leaf biomass was reduced most strongly by defoliation, and crowns were least affected. Yield of biomass and nutrients to grazers (green leaves+clipped material) was enhanced by weekly defoliation in the shortgrass grazing-adapted species, whereas yield to producers (live biomass and nutrients retained by the plant) and yield to decomposers (litter) were strongly reduced by defoliation in all species. Phosphate absorption capacity (V max) measured on excised roots was enhanced by defoliation in the grazing-adapted Sporobolus, but, due to low affinity (high K m) of roots of defoliated plants for phosphate, absorption rate was not greatly altered at low solution concentrations. Phosphate absorption capacity was reduced or unaffected by defoliation in other species. We conclude that under conditions of P deficiency, plants are unable to acquire the nutrients necessary to replenish large nutrient losses to grazers. In low-nutrient environments, compensatory growth (stimulation of production by grazing) is not a viable strategy. Therefore, in these environments plants respond evolutionarily to herbivores by developing chemical or morphological defenses.

Effect of phosphorus supply on three perennial Stylosanthes species in tropical Australia. I. Vegetative and reproductive growth

Three perennial Stylosanthes species (S. scabra cv. Seca, S.guianenis cv. Schofield and S. viscosu CPI 34904) were grown on a soil of low acid-extractable (0.005 M H2SO4) P status (4 mg/kg) and supplied with either 0 (P0) or 50 kg P/ha (P50) to test their ability to grow under phosphorus-deficient conditions. Plants were grown in the field for two years (1978 and 1979), during which time dry matter yields of standing plant shoots, leaves, stems, inflorescence, podded seed and litter were recorded regularly.Perennial stylo, but especially Seca, grew well and produced high seed yields under conditions of low soil phosphorus. Based on their growth rates during the second wet season, tolerance to low phosphorus conditions decreased as follows: Seca> Schofield >CPI 34904. Two factors favouring Seca were its ability to allocate much of its dry matter to stem and its high yield of fine roots. Positive effects of phosphorus application occurred with leaf, stem, inflorescence, seed and litter yields, but were generally similar for the three species. There were large differences in dry matter distribution between species and little effect of applied phosphorus. Features were the high percentage of stem in Seca, and of inflorescence and seed in CPI 34904.

Phosphorus and Carbon Economies of Ectomycorrhizal Seedlings of Eucalyptus pilularis Smith

The distribution patterns of phosphorus and carbon in Eucalyptus pilularis Smith seedlings raised in phosphorus-deficient conditions for at least 4 months have been examined. These seedlings possessed well developed ectomycorrhizas and there was significant retention of phosphorus by the mycorrhizal roots at low levels of phosphorus supply. A high proportion of residue phosphorus (possibly polyphosphate) was found in mycorrhizal roots and also in foliage at a level of deficiency at which very little storage phosphorus would be expected to remain. There was evidence of a control mechanism, perhaps operating via this 'storage' pool, which guarded against any overstimulation of growth rate in response to periodic increases in soil phosphorus. This control acted by regulating the amount of phosphorus available for photosynthesis, especially in those leaves with the highest potential to export carbon for growth. It is proposed that the E. pilularis seedlings combine strategies which characterize fast-growing and slow-growing species, namely a responsiveness of photosynthesis to available phosphorus in the foliage and foliar storage of phosphorus when supply persists. Such flexibility may contribute to this species being able to compete successfully in a range of habitats of varying nutritional status.

The ATP and Total Adenine Nucleotide Content of Four Unicellular and Colonial Green Algae

The ATP and total adenine nucleotide content (TANC) of two unicellular and two colonial green algae were measured in conditions of nitrogen and phosphorus deficiency and during exponential growth. The ATP content ranged from 0.07 to 0.44% (mean = 0.25%) of the cellular organic carbon during exponential growth and the TANC varied from 0.28 to 0.79% (mean = 0.53%). ATP and TANC decreased during nitrogen and phosphorus deficiency to values between 2 and 31% of the content in exponentially growing cells. Large errors are expected when cellular organic carbon is calculated from ATP data in natural environments dominated by green algae, whereas TANC gives a better estimate of biomass.

Multiple Forms of Orthophosphoric Monoester Posphohydrolase in Phosphate Starved Wolffia arrhiza

Phosphatase forms from axenic batch cultures of Wolffia arrhiza, strain WJ, were investigated under normal (P +) or phosphorus deficient (P −) conditions. Electrophoretic separation of orthophosphoric monoester phosphohydrolase on polyacrylamide-gel showed marked changes in the band pattern after phosphate starvation. Tree low rp multiple forms (α-bands) resistant to heat (10 min. 80°C) are typical for (P −) plants. The α2-enzyme could not be detected in (P +) plants, while the α1- and α3-enzymes were faintly coloured in gels of concentrated (P +) extracts. Most of the phosphatase activity of (P +) plants was found to have high rp-values (γ-bands), these enzyme forms were completely inactivated by heat treatment (10 min, 75°C). While the γ1 and γ2-bands are present in (P +) as well as n (P −) plants, the γ3-enzyme could only be detected in (P −) plants. The highest heat stability of all the phosphatase forms was shown by the enzyme β2, which occurred in (P −), but not in (P +) plants. In concentrated media of (P −) plants, α-enzyme forms as well as the β2-enzyme could be detected, whereas no γ-enzyme forms were found. In (P +) plants no evidence of the release of phosphohydrolases is provided.

A study of phosphorus nutrition and water supply on the early growth and survival of buffel grass grown on a sandy red earth from south-west Queensland

The influence of phosphorus application on the growth and drought survival of buffel grass on a sandy red earth in south west Queensland was studied in a series of pot experiments. An omission nutrient trial showed phosphorus was the principal nutrient limiting seedling growth, the severity of the deficiency increasing with time. A further pot experiment showed that at rates greater than 24 kg P ha-1 luxury consumption occurred. The critical phosphorus concentration for the plant was estimated to be 0.26 per cent. The available (0.01 NH2SO4 extractable) soil phosphorus concentration corresponding to this critical tissue concentration was 25 p.p.m. Beyond the 2-leaf seedling stage, the seedling depended increasingly on external phosphorus for growth. Under conditions of phosphorus deficiency, phosphorus absorption rates were insufficient to maintain tissue phosphorus at the concentrations necessary for healthy growth, and relative growth rates were low. In the presence of phosphorus, absorption and growth rates increased. Maturity of phosphorus deficient plants was characteristically delayed but with little yield loss. The addition of phosphorus increased seedling growth rate, root development and drought survival. The depth of root penetration is considered to be the major factor responsible for survival.

Nitrogen accumulation induced by phosphorus deficiency in citrus plants

Growth responses and nitrogen constituents were tested in young citrus trees grown on gradually decreasing amounts of phosphorus in greenhouse solution cultures. The phosphorus concentration in dry matter of minus-P leaves dropped to a third of that in control leaves and then remained steady throughout the experiment, while the total nitrogen concentration was low at the beginning and, rising gradually, reached an enormous amount. Nitrogen estimations in minus-P leaves showed the specific dynamics of the soluble nitrogen fraction: its content was low at the onset of the deficiency, and rose rapidly due to intensive accumulation of arginine in the tissues. Under conditions of acute phosphorus deficiency, arginine constituted more than 60% of the free amino acids and arginine nitrogen above 40% of the total, while in normal leaves arginine did not exceed 8% of the free amino acids, and about 1–% of the total. Similar patterns of increased nitrogen level due to arginine accumulation were found in leaves of phosphorus-deficient grapefruit and orange trees under field conditions.

Nitrogen and Carbohydrate Metabolism of Japanese Mint as Affected by Phosphorus Deficiency and Seasonal Variations

AbstractThe paper presents effects of phosphorus deficiency and seasonal variations on nitrogen and carbohydrate metabolism of Japanese mint (Mentha arvensis L. var. piperascens, Holmes). Mint plants were grown in sand cultures under full nutrition and under phosphorus deficiency conditions during winter and summer. Various nitrogen and sugar fractions were determined in the component parts at specified periods of growth stages. Phosphorus deficiency disturbed the nitrogen metabolism at the stages for amide and amino acid formation, which resulted in an accumulation of carbohydrates. The content of total soluble and total nitrogen was higher and that of insoluble nitrogen was lower in summer as compared with winter plants. Of the soluble fractions, the ammonia, amide and nitrate nitrogen were higher and the ‘rest’ nitrogen lower in winter plants. Nitrate formed the highest bulk of the pool of soluble nitrogen in winter, whereas in summer ‘rest’ nitrogen was most abundant. The content of total sugar in winter plants far exceeded that of summer plants, which was wholly due to increase in sucrose content. Glucose was the predominant reducing sugar in both seasons. However, the summer plants were richer in glucose than those from the winter.

Effect of Phosphorus Deficiency on Carbohydrate Metabolism of Mentha arvensis

AbstractThe effects of phosphorus deficiency on carbohydrate fractions of Mentha arvensis L. var. piperascens were studied. Mint plants were grown in sand cultures under full nutrition and phosphorus deficiency conditions. Component organs, viz., leaf, stem and root, were sampled at four different stages of the growth cycle and analysed for various sugar fractions.In leaf and root phosphorus deficiency brought about a definite increase in all sugar fractions whereas in stem a reduction was noticed. The stem appeared to be the principal storage organ throughout the growth. Maximum sugar concentration was recorded at the age of 70 days, which represents the full maturity stage, and coincided with maximum essential oil accumulation.

The growth of watercress (Rorippa nasturtium aquaticum (L) Hayek) from seed as affected by the phosphorus nutrition of the parent plant

Seed was collected from watercress plants grown in sand cultures supplied with nutrient solutions containing either 0.2, 1.0, or 4.0 me/l of phosphorus. The seed, called P1, P2, and P3 seed respectively, contained 0.47, 0.84, and 0.95 per cent P, while other differences in its composition and in its size were relatively slight. When grown under conditions of phosphorus deficiency, 7- to 9-week-old plants from P3 seed were larger than those from P2, which in turn were larger than those from P1 seed, but such differences were not measurable when the plants were mature at 16 to 20 weeks. When grown in cultures adequately supplied with phosphorus there were no differences between the weights of plant from any of the three kinds of seed either at 6 to 7 weeks or at 16 to 20 weeks. The different levels of phosphorus supply in the first generation had no measurable effects on 6 1/2-week-old plants in the third generation.