Localization of acid phosphatase activity in the apoplast of pea (Pisum sativum L.) root nodules grown under phosphorus deficiency

ACPase activity was localized in the apoplast of pea root nodules under phosphorus deficiency. Pea plants (Pisum sativum L. cv. Sze ciotygodniowy) where inoculated with Rhizobium leguminosarum bv. viciae 248 and were cultured on nitrogen-free medium with phosphate (−N/+P) or phosphate-deficient (−N/−P) one. In comparison with control nodules, P-deficient nodules showed the increase of ACPase activity in plant cell walls and the infection threads. The increase in bacterial ACPase activity under P-deficiency may reflect higher demand for inorganic phosphorus that is necessary for bacteria multiplication within the infection threads. The increase of ACPase activity in nodule apoplast under P stress may enlarge the availability of phosphate for plant and bacteria.     

Induction of maize acid phosphatase activities under phosphorus starvation

Large variation in phosphorus-(P) acquisition efficiency exists among maize inbred and hybrid genotypes. Acid phosphatases are a type of enzyme that affects P acquisition and P-use efficiency in plants. The objectives of this research were (1) to characterize acid phosphatase activity in maize grown hydroponically under P starvation, and (2) to determine if there is differential induction of acid phosphatases in two maize genotypes previously characterized as P efficient (Mo17) and P inefficient (B73). B73 and Mo17 seedlings were grown hydroponically and both intracellular and secreted acid phosphatase activities were characterized. Fresh seedling weight of both genotypes decreased under P starvation, but percent fresh weight allocated to roots increased 14 days after P starvation in B73. Soluble protein concentration in shoots and roots was affected little, but secreted protein decreased by 40 and 20% in B73 and Mo17 seedlings grown without P for 14 days. Intracellular and secreted acid phosphate activity increased substantially in leaves and roots in B73 and Mo17 in response to P starvation. Secreted APase activity per unit protein increased 310 and 300% in B73 and Mo17, respectively, 7 days after P withdrawal. One of the minor isozymes identified on non-denaturing PAGE, was increased specifically in response to P starvation in both maize genotypes. The patterns and levels of change in APase activities in B73 and Mo17 were not sufficiently different to account for the diverse growth response of these genotypes in low-P conditions. The results suggest that APases may not be a major mechanism for scavenging or acquiring P and changes in APases may reflect a state of P stress in both varieties. Other factors such as root architecture, secretion of low-molecular weight carboxylates and microbial interactions might explain the difference between these two genotypes.     

Fine mapping of quantitative trait loci for acid phosphatase activity in maize leaf under low phosphorus stress

Acid phosphatase (APase) is very important in phosphorus (P) scavenging and remobilization in plants. The aim of this study was the fine mapping of quantitative trait loci (QTL) for APase activity (APA) in maize (Zea mays L.) leaf. The QTL for APA were studied in the F2:3 population derived from the cross 082 × Ye107 under low P stress in two sites. A significant difference in APA was found between 082 (P-efficient genotype) and Ye107 (P-deficient genotype). Each environment was analyzed to identify the QTL. Six QTL for APA were found, comprising two QTL at Beibei (BB) and four QTL at Hechuan (HC), China. A QTL denoted as AP9 showed a stable expression under different environments on chromosome 9, and explained 10.21 and 16.81 % of phenotypic variation at BB and HC, respectively. For the fine mapping of this QTL, seven individuals selected via marker-assisted selection in the BC3F1 population were used to produce the BC3F2 lines by selfing and to allow recombination within the region containing the target QTL. High-resolution genetic and physical maps were further constructed for the fine mapping of AP9 using 12 simple sequence repeat markers and the BC3F2 population consisting of 1,441 individuals. As a result, the location of AP9 was narrowed down to a 546-kb fragment on chromosome 9.     

Acid phosphatase activity in maize leaves as related to their evolution and phosphorus deficiency

The effect of phosphorus deficiency on the activity of acid phosphatase of the first, second and third leaves of maize plants was followed. The supernatant obtained by centrifuging the homogenate of plant tissue at 1500 ×g was further centrifuged at 18 000 ×g, the sediment marked as fraction II and the supernatant as fraction III. Acid phosphatase activity of fraction II of the first to third leaves was for the whole period of culture higher in plants grown in the nutrient solution without phosphate. In fraction III this relation was established in the first leaf, after 3 days of culture in the second leaf and after 5 days in the third leaf. In all leaves higher enzyme activity was unambiguously determined in fraction III when compared with fraction II. Higher acid phosphatase activity was established in those leaves which were younger in their development, particularly in the first days of culture. With the ageing of leaves the enzyme activity decreased.     

The effect of exogenous phosphate deficiency on the activity of acid phosphatase of the root of two maize genotypes

In two maize genotypes, the effect of exogenous phosphate deficiency on acid phosphatase activity of the apical part of primary root was followed in dry and imbided grains. Higher acid phosphatase activity was found in the genotype LG 5. The enzyme activity increased after 18 h grain imbibition in the two genotypes. After 48 h germination no differences were found between the genotypes. After 24 h cultivation of root segments in a solution of 0.25 mM CaSO₄.2H₂O,0.1 mM MgSO₄.7H₂O, and further after 3,6 and 24 h cultivation in solutions with and without phosphate genotypic differences were found in acid phosphatase activity as well as in dry mass production. An increase in enzymatic activity due to exogenous phosphate deficiency was registered in the two genotypes only after 24 h cultivation.     

Localization of acid phosphatase in the differentiating root meristem

The localization of acid phosphatase was studied by Gomori’s newer technique and by azo-coupling methods (α-naphthyl phosphate + fast red ITR or fast garnet GBC; AS or AS D phosphate + fast blue B or fast red violet LB) in the root tips ofVicia faba L. on paraffin sections (fixation with Wolman’s acidified ethanol) and on frozen sections (fixation with Baker’s calcium formol). Analogous results were obtained on the material treated in various ways and using different methods. In the broad bean, the reaction is most intense in the cap. In the meristematic zone, the primary core is more intensely stained than the ground parenchyma of the central cylinder. The phloem and xylem poles are usually strongly positive. Using both types of methods on Wolman fixed paraffin embedded material, essentially the same localization of acid phosphatase was found in the root tips ofRicinus communis L.,Lupinus luteus L.,Sinapis alba L.,Allium cepa L. as in the broad bean. InZea mays L. the rhizodermis and the hypodermic layers of the primary core were found to be most active. On sections of Wolman fixed paraffin embedded broad bean the most intense reaction was observed at pH 4.2–4.8. In the same material, both the azo-coupling and the Gomori reaction is inhibited by 10⁼² M NaF, but 10^?2 M tartaric acid only inhibits the Gomori reaction.     

缺磷条件下的小麦根系酸性磷酸酶活性研究

1　引　　言植物根可向根际分泌许多有机化合物 ,其中有许多物质都能促进植物对矿质养分的吸收 .作为必需大量营养元素的Ｐ ,在土壤中以无机磷酸盐阴离子的形式被吸收 ,而有机磷酸酯必须被水解成无机Ｐ后才能进入植物根 ,在这一过程中有一非常重要的步骤 ,就是由微生物、菌根外真菌和植物根分泌酸性磷酸酶 .土壤中的有机Ｐ一般占全Ｐ的 30 %～ 5 0 % ,有的可达95 % .因此 ,如何发挥植物自身利用土壤有机Ｐ的潜力已成为目前植物营养学研究的热点之一 .Ｇｏｌｄｓｔｅｉｎ等[3 ] 研究Ｐ胁迫条件下悬浮培养细胞时发现 ,抑制植物生长和诱导酸性…     

Stimulation of root acid phosphatase by phosphorus deficiency is regulated by ethylene in Medicago falcata

Plants have developed numerous strategies to cope with phosphorus (P) deficiency resulting from low availability in soils. Evolution of ethylene and up-regulation of root secreted acid phosphatase activity are common for plants in response to P deficiency. To determine the role of ethylene in response of plants to P deficiency, we investigated the effects of ethylene precursor (1-amino cyclopropane-1-carboxylic acid, ACC) and ethylene synthesis antagonists (aminoethoxyvinylglycine AVG, cobalt, Co²⁺) on P concentrations in roots and shoots of Medicago falcata seedlings grown in P-sufficient (500 μM H₂PO₄⁻) and P-deficient (5 μM H₂PO₄⁻) solution. After transferring M. falcata seedlings from P-sufficient to P-deficient solution for 2 days, root P concentration was significantly reduced. The reduction in root P concentration was reversed by AVG and Co²⁺, and a similar reduction in root P concentration of seedlings exposed to P-sufficient solution was observed by ACC. Expression of high-affinity phosphate transporters (MfPT1, MfPT5) was enhanced by P-deficiency and this process was reversed by AVG and Co²⁺. There was a marked increase in activity of root acid phosphatase (APase) and expression of gene encoding APase (MfPAP1) under P-deficient conditions, and the increase in APAse activity and expression of MfPAP1 was inhibited by AVG and Co²⁺. APase activity and expression of MfPAP1 expression in seedlings grown in P-sufficient solution were enhanced by ACC. Root and shoot P concentrations were increased when organic phosphorus was added to the P-deficient solution, and the increase in P concentration was significantly inhibited by AVG and Co²⁺. These results indicate that ethylene plays an important role in modulation of P acquisition by possibly mobilizing organic P via up-regulating root APase activity and high-affinity phosphate transporters.     

Growth analysis of maize field crops under phosphorus deficiency

Biomass accumulation by crops depends both on light interception by leaves and on the efficiency with which the intercepted light is used to produce dry matter. Our aim was to identify which of these processes were affected for maize (Zea Mays L., cv Volga) field crops grown under phosphorus (P) deficiency, and assess their relative importance. In this paper, the effects of P deficiency on leaf appearance, leaf elongation rate, final individual leaf area and leaf senescence were studied. The experimental work was carried out in 1995–1977 on a long-term P fertilisation trial located on a sandy soil in the south-west of France. Three P fertilisation regimes have been applied since 1972: no-P (P0 treatment) and different rates of P fertiliser (P1.5:1.5 times the grain P export and P3:3 times the grain P export). These fertilisation regimes have led to contrasted levels of soil P supply, with the P0 treatment being limiting for growth. Very few differences were observed about leaf growth between the P1.5 and P3 treatments. Conversely, the leaf area index (LAI) was significantly reduced in the P0 treatment, especially during the first phases of the crop cycle (up to −60% between the 7- and 14-visible leaves). This effect gradually decreased over time. The lower LAI in P0 treatment was due to two main processes affecting the leaf growth. The final number of leaves per plant and leaf senescence were only slightly modified by P deficiency. Conversely, leaf appearance was delayed during the period between leaf 4 and leaf 9. The value of the phyllochron increased from 47 °C days in the P1.5 treatment to 65 °C days in the P0 treatment. Leaf elongation rates during the quasi-linear phase of leaf expansion were significantly reduced for lower leaves of P0 plants. The final size of leaves L2–L12 was reduced. On the opposite, leaf elongation duration was not greatly affected by P treatments. Before the emergence of leaf 9, the reduction of individual leaf size was the main factor responsible for the reduced LAI in the P0 treatment. After this stage, the delayed leaf appearance accounted for a great part of the reduced LAI in the P0 treatment. This revised version was published online in June 2006 with corrections to the Cover Date.     

Uses of alkaline phosphatase activity in evaluating phytoplankton community phosphorus deficiency

The phosphorus (P) deficiency status of phytoplankton communities was measured using the physiological indicator, alkaline phosphatase activity (APA) and nutrient-addition growth bioassays in field sampled from four northeastern Minnesota lakes and the far western arm of Lake Superior. Phosphorus additions generally reduced APA, while other treatments increased activity. Samples receiving nitrogen (N) and P increased APA after a long lag period. P-addition bioassays of Lake Superior were consistent with phytoplankton P limitation and variations in APA indicated potential seasonal and spatial changes in P deficiency status. The results suggest that APA reliably reflected the phytoplankton P status, but may not provide sufficient information when N or NP limitation is present.     

Localization of acid phosphatase activity in collagen-secreting and collagen-resorbing fibroblasts

The ultrastructural localization of acid phosphatase (ACPase) activity was examined in cultured human gingival fibroblasts in the formative and resorptive phases. In the collagen-secreting fibroblasts, weak ACPase activity was demonstrated in the lysosomes, inner Golgi cisternae, and condensing vacuoles, and none was found in the Golgi-associated endoplasmic reticulum-lysosome system (GERL), presecretory granules, or secretory granules. On the contrary, collagen phagocytosis induced strong ACPase activity in the GERL, which was in addition to the weaker activity found in the same sites as those in the collagen-secreting cells. At the same time, collagen secretion was suppressed, and dense elongated secretory bodies associated with ACPase activity accumulated within the cells. When collagen fibrils had been interiorized in whole or in part within the phagosomes, primary lysosomes derived from the Golgi-GERL complex then fused with them to form phagolysosomes. Collagen degradation occurred within these bodies. The observations indicate significant differences in ACPase activity used as a marker for lysosomal enzyme activities in the different functional phases of fibroblasts. These results suggest that fibroblasts work only one way at a given time, viz., collagen synthesis or collagen degradation.     

Localization of acid phosphatase activity in collagen-secreting and collagen-resorbing fibroblasts

Summary The ultrastructural localization of acid phosphatase (ACPase) activity was examined in cultured human gingival fibroblasts in the formative and resorptive phases.In the collagen-secreting fibroblasts, weak ACPase activity was demonstrated in the lysosomes, inner Golgi cisternae, and condensing vacuoles, and none was found in the Golgi-associated endoplasmic reticulum-lysosome system (GERL), presecretory granules, or secretory granules. On the contrary, collagen phagocytosis induced strong ACPase activity in the GERL, which was in addition to the weaker activity found in the same sites as those in the collagen-secreting cells. At the same time, collagen secretion was suppressed, and dense elongated secretory bodies associated with ACPase activity accumulated within the cells. When collagen fibrils had been interiorized in whole or in part within the phagosomes, primary lysosome derived from the Golgi-GERL complex then fused with them to form phagolysosomes. Collagen degradation occurred within these bodies. the observations indicate significant differences in ACPase activity used as a marker for lysosomal enzyme activities in the different functional phases of fibroblasts.These results suggest that fibroblasts work only one way at a given time, viz., collagen synthesis or collagen degradation.     

Arbuscular mycorrhizal colonization outcompetes root hairs in maize under low phosphorus availability

Background and AimsAn increase in root hair length and density and the development of arbuscular mycorrhiza symbiosis are two alternative strategies of most plants to increase the root–soil surface area under phosphorus (P) deficiency. Across many plant species, root hair length and mycorrhization density are inversely correlated. Root architecture, rooting density and physiology also differ between species. This study aims to understand the relationship among root hairs, arbuscular mycorrhizal fungi (AMF) colonization, plant growth, P acquisition and mycorrhizal-specific P_i transporter gene expression in maize.MethodsUsing nearly isogenic maize lines, the B73 wild type and the rth3 root hairless mutant, we quantified the effect of root hairs and AMF infection in a calcareous soil under P deficiency through a combined analysis of morphological, physiological and molecular factors.Key ResultsWild-type root hairs extended the rhizosphere for acid phosphatase activity by 0.5 mm compared with the rth3 hairless mutant, as measured by in situ zymography. Total root length of the wild type was longer than that of rth3 under P deficiency. Higher AMF colonization and mycorrhiza-induced phosphate transporter gene expression were identified in the mutant under P deficiency, but plant growth and P acquisition were similar between mutant and the wild type. The mycorrhizal dependency of maize was 33 % higher than the root hair dependency.ConclusionsThe results identified larger mycorrhizal dependency than root hair dependency under P deficiency in maize. Root hairs and AMF inoculation are two alternative ways to increase P_i acquisition under P deficiency, but these two strategies compete with each other.     

Localization of acid phosphatase activity in the liver of pregnant rats

Synopsis In the liver of pregnant rats, fedad libitum, there was an increase in acid phosphatase specific activity which occurred in two peaks, one at the 15th day and the other at the end of gestation. By light and electron microscopic histochemistry, the activity was found to be localized in parenchymal cell peribiliary dense bodies and also in phagosomes present in macrophages and parenchymal cells. There was an increase in liver weight which reached a peak at the 17th day of gestation. Total DNA also rose to the 17th day; there was a high rate of cell division in the hepatic parenchyma at the 17th and 18th days of gestation. During this period single cell deletion by apoptosis was relatively frequent and in late pregnancy there was evidence of cell deletion by lysis.During pregnancy there was a slight increase in sinusoidal macrophages as a proportion of the total cell population but there did not appear to be significant changes in macrophage enzymic activity. It is suggested that the acid phosphatase activity present in macrophages makes a minor contribution to total liver activity, most of which is present in parenchymal cells. Acid phosphatase activity associated with single cell deletion appears to be quantitatively negligible.There was a direct relationship between total hepatic acid phosphatase activity and the numbers of peribiliary dense bodies, which were most numerous at the 15th day and at the end of gestation. It is suggested that these residual bodies contain products of detoxification processes and also cell structural elements resulting from enhanced liver metabolism and intracellular turnover during pregnancy.     

A role for redox factors in shaping root architecture under phosphorus deficiency

The developmental response of the Arabidopsis root system to low phosphorus (P) availability involves the reduction in primary root elongation accompanied by the formation of numerous lateral roots. We studied the roles of selected redox metabolites, namely, radical oxygen species (ROS) and ascorbic acid (ASC) in the regulation of root system architecture by different P availability. Rapidly growing roots of plants grown on P-sufficient medium synthesize ROS in root elongation zone and quiescent centre. We have demonstrated that the arrest of root elongation at low P medium coincides with the disappearance of ROS from the elongation zone. P-starvation resulted in a decrease in ascorbic acid level in roots. This correlated with a decrease in cell division activity. On the other hand, feeding P-deficient plants with ASC, stimulated mitotic activity in the primary root meristem and partly reversed the inhibition of root growth imposed by low P conditions. In this paper, we discuss the idea of the involvement of redox agents in the regulation of root system architecture under low P availability.Key words: ascorbic acid, phosphate deficiency, primary root, radical oxygen species, root growth, root system architecture     

Localization of acid phosphatase activity in Giardia lamblia and Giardia muris trophozoites

Numerous membrane-bounded vacuoles are found adjacent to the plasma membrane of the pathogenic protozoan Giardia lamblia. The function of these vacuoles has been discussed by several authors. Approximately 100-400 nm in diameter with a core of low electron density, they have been suggested to be mitochondria, mucocysts, lysosomes, and endocytotic vacuoles. Enzyme cytochemical localization for acid phosphatase activity using cerium as a capturing agent demonstrates reaction product in these vacuoles as well as in the endoplasmic reticulum and nuclear envelope cisternae. The distribution of reaction product suggests the vacuoles are lysosome-like; however, their function and development remain in question.     

Secreted acid phosphatase is expressed in cluster roots of lupin in response to phosphorus deficiency

The roots of white lupin (Lupinus albus L. cv. Kievskij mutant) secrete acid phosphatase, S-APase, when they grow under conditions of low available phosphorus (P). S-APases hydrolyze organic phosphate compounds in the rhizosphere and supply inorganic phosphate to the plants. Low phosphorus availability also induces vigorous growth of cluster roots. In this study, the function of cluster roots was investigated with reference to S-APase secretion. White lupins were grown in hydroponic culture in a greenhouse under P-deficient and P-sufficient conditions. S-APase in the excised roots after treatment was detected by staining with 4-methylumbelliferone phosphate (MUP). Gene expression of S-APase in cluster and normal roots was also investigated. Activity was greatest in the roots of plants grown under conditions of P -deficiency, particularly in cluster roots. S-APase gene expression was induced by a decrease in internal P concentrations, and was especially high in cluster roots formed under conditions of P -deficiency. It was suggested that decrease of internal P concentration stimulated both of the S-APase expression and cluster root formation.