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PubMed2001

Growth of conifer seedlings on organic and inorganic nitrogen sources.

Effects of organic and inorganic nitrogen sources on growth and mineral nutrient concentrations of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings were compared in a 100-day experiment in a greenhouse. Seedlings were grown in pots containing peat. Nutrient solutions differing in ammonium, nitrate, arginine and glycine composition were supplied to the seedlings at three nitrogen (N) concentrations: 1, 3 and 10 mM. We used dual (13C, 15N) and single (15N) isotopic labeling to determine the uptake of organic and inorganic N at the end of the experiment. Seedling dry weights and mineral nutrient concentrations of the needles showed that both conifer species were able to grow well and maintain nutrient balance on all investigated N forms except for the ammonium-dominated nutrient mixtures at the 10 mM N concentration. In Scots pine, no significant differences in dry weights were found between seedlings grown on the amino acids and seedlings grown on a commercial fertilizer containing 61.5% NO(3-)-N and 38.5% NH(4+)-N. Isotopic labeling of seedlings indicated that uptake rates of arginine-N, glycine-N and NH(4+)-N were similar, and 7-8 times greater than uptake rates for NO(3-)-N in both species. In Scots pine seedlings, 100% of arginine-N, and at least 67% of glycine-N was derived from the uptake of intact amino acids through seedling roots or mycorrhizae. Corresponding figures for Norway spruce were 83% for arginine and 96% for glycine. The gas chromatography-mass spectrometry analyses confirmed the presence of intact labeled molecules of both arginine and glycine in seedlings. We conclude that arginine and glycine are comparable to inorganic N as N sources for growth of conifer seedlings.

Amino Acids↗
PubMed2001

Rates and quantities of carbon flux to ectomycorrhizal mycelium following 14C pulse labeling of Pinus sylvestris seedlings: effects of litter patches and interaction with a wood-decomposer fungus.

We used a novel digital autoradiographic technique that enabled, for the first time, simultaneous visualization and quantification of spatial and temporal changes in carbon allocation patterns in ectomycorrhizal mycelia. Mycorrhizal plants of Pinus sylvestris L. were grown in microcosms containing non-sterile peat. The time course and spatial distribution of carbon allocation by P. sylvestris to mycelia of its mycorrhizal partners, Paxillus involutus (Batsch) Fr. and Suillus bovinus (L.): Kuntze, were quantified following 14C pulse labeling of the plants. Litter patches were used to investigate the effects of nutrient resource quality on carbon allocation. The wood-decomposer fungus Phanerochaete velutina (D.C.: Pers.) Parmasto was introduced to evaluate competitive and territorial interactions between its mycelial cords and the mycelial system of S. bovinus. Growth of ectomycorrhizal mycelium was stimulated in the litter patches. Nearly 60% of the C transferred from host plant to external mycorrhizal mycelium (> 2 mm from root surfaces) was allocated to mycelium in the patches, which comprised only 12% of the soil area available for mycelial colonization. Mycelia in the litter patch most recently colonized by mycorrhizal mycelium received the largest investment of carbon, amounting to 27 to 50% of the total 14C in external mycorrhizal mycelium. The amount of C transfer to external mycelium of S. bovinus following pulse labeling was reduced from a maximum of 167 nmol in systems with no saprotroph to a maximum of 61 nmol in systems interacting with P. velutina. The 14C content of S. bovinus mycelium reached a maximum 24-36 h after labeling in control microcosms, but allocation did not reach a peak until 56 h after labeling, when S. bovinus interacted with mycelium of P. velutina. The mycelium of S. bovinus contained 9% of the total 14C in the plants (including mycorrhizae) at the end of the experiment, but this was reduced to 4% in the presence of P. velutina. The results demonstrate the dynamic manner in which mycorrhizal mycelia deploy C when foraging for nutrients. The inhibitory effect of the wood-decomposer fungus P. velutina on C allocation to external mycorrhizal mycelium has important implications for nutrient cycling in forest ecosystems.

Autoradiography↗
PubMed1990

Needle growth in Sitka spruce (Picea sitchensis): effects of nutrient deficiency and needle position within shoots.

Needle development and shoot growth were studied in 14- and 20-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) planted on an oligotrophic peat and fertilized with N, P and K (control), N and P (-K), N and K (-P) or unfertilized (-NPK). Shoot extension, needle number, and the size and number of needle cells were observed throughout the season. Beginning with bud burst in early May, needle growth continued for nine weeks in the control treatment. Needle growth in the mineral deficiency treatments terminated at the same time as in the controls, although it did not begin until up to three weeks later than in the control trees. Needles developed acropetally along the shoot, with basal needles completing their development first. Cell division in needles of control trees lasted about 3 weeks, with cell expansion continuing for a further 3 weeks. Initial mean cell cycle times were shortest for proximal needles following bud burst, but lengthened as the season progressed. Cell number increased from 6600 in the primordia to 200 000 in mature needles. Final needle dimensions and cell number varied according to the position of the needle on the shoot. The largest needles with the most cells were near the middle of the shoot. Relative to the controls, all mineral deficiency treatments reduced shoot length, bud and needle dimensions, and needle cell number, particularly the -P treatment. Potassium and P deficiency treatments reduced primordial cell number by up to 42%, whereas final mean cell size was 30% greater in the -P treatment, 17% greater in the -NPK treatment, but 14% smaller in the -K treatment. Mean cell size was constant for needles at all positions in any particular treatment at any time, so that final needle size was determined by cell number alone. Needle dry weight/fresh weight ratio continued to increase until early August, with significantly higher ratios in the -K and -P treatments than in the controls.

Journal Article↗
PubMed1989

Seasonal variation of soil-to-plant transfer of K and fallout 134,137Cs in peatland vegetation.

For three plants from a peat bog (Trichophorum caespitosum, Molinia coerulea, Calluna vulgaris) the concentration of 137Cs, the ratio 137Cs:134Cs, and stable K was determined in intervals of about 14 d from June to November 1987. The results show that for two grasses, Trichophorum caespitosum and Molinia coerulea (which have only perennial roots but sprout every year while the old leaves wither), the concentration of 137Cs decreased considerably during the growing season (1800-240, respectively, 4000-320 Bq kg-1 dry weight). A remarkably similar behavior was observed for the seasonal variability of K and radiocesium in the two grass species, which resulted in a nearly constant ratio of 137Cs:K during the year. In contrast, for the evergreen plant Calluna vulgaris (heather) which was contaminated surficially by the Chernobyl fallout, the concentrations of K and 137Cs were rather constant during 1987 (leaves about 10,000; stems about 5000 Bq kg-1 dry weight), even though radiocesium was taken up by the leaves and transported within the plant. For the two grasses, the plant:soil concentration ratios (CR) were obtained separately for total 137Cs, 137Cs from the global fallout, and Chernobyl-derived 137Cs. The CR of 137Cs from the global fallout decreased for Trichophorum caespitosum from 1.9 in the spring to 0.08 in the autumn, and for Chernobyl-derived 137Cs from 1.4 to 0.2. For Molinia coerulea, a similar behavior was observed. Possible reasons for the seasonal variability of the CR values and the different behavior of 137Cs from the global fallout and from the Chernobyl debris are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cesium Radioisotopes↗
PubMed1991

Abandoned Rayrock uranium mill tailings in the Northwest Territories: environmental conditions and radiological impact.

Field and laboratory investigations were undertaken of the environment surrounding abandoned U mill tailings at Rayrock, Northwest Territories, Canada, to examine the extent of 226Ra and U contamination. Samples of ground water, surface water, and unconsolidated geological material from the Rayrock area were collected for chemical and radiochemical analyses. Results indicated that the surface waters contained levels of 226Ra as high as 20 Bq L-1, 210Pb as high as 1.1 Bq L-1, and ground water U as high as 2800 micrograms L-1. Lower levels of 226Ra, 210Pb, and U, 3.6 Bq L-1, 0.5 Bq L-1, and 4 micrograms L-1, respectively, were found in a small lake adjacent to the tailings area. Analysis of tailings and soil in the immediate vicinity indicates that the radionuclides and U are mobilized and can move within the tailings. Some of the mobilized radionuclides will be bound by the surrounding peat. The remainder may move to Lake Alpha in ground water. Surface water flow also transports some contaminants both in the water of Alpha Creek and by washing tailings into Lake Alpha. The potential annual external and internal dose equivalents to a hypothetical resident were calculated based on exposure from the abandoned U mill tailings, drinking water, and fish caught in the lakes in the vicinity of the tailings. While Alpha Creek and Lake Alpha water showed evidence of contamination, the rest of the water system and the fish were at natural background levels of radioactivity.

Animals↗
PubMed1991

Chernobyl fallout in southern and central Finland.

To study the levels and distributions of radionuclides released in the Chernobyl accident, we sampled surface peat from 62 sites in Southern and Central Finland and measured 131I, 134Cs, 137Cs, 132Te, 140Ba, 103Ru, 90Sr, 141Ce, and 95Zr. The distribution of fallout activities was highly uneven, depending on movement of the contaminated air mass and rainfall distribution during the critical days. The highest values observed were 420 kBq m-2 of 131I and 70 kBq m-2 of 137Cs. The nuclide ratios showed wide and partly unexpected variations. The high-boiling-point, or nonvolatile, elements Ce and Zr were spread mostly on a 200-km-wide zone extending across Finland from southwest to northeast. The more volatile elements, I, Ce, and Te, showed quite a different, more widespread, fallout distribution, while an intermediate behavior was observed for Ba, Ru, and possibly Sr. These results can be explained by assuming that pulverized nuclear fuel material released in the reactor explosion on 26 April reached Finland via Poland and the Baltic Sea and traversed the country along the above-mentioned narrow zone, while volatile material, evaporated in the reactor fire from 26 April to 5 May, arrived in several waves and was consequently more widely and evenly spread. From their elemental melting and boiling points, Ru and Mo would appear to belong to the nonvolatile group and Sr to the volatile. Yet, their actual behaviors were opposite; Ru in particular was found in the nonvolatile as well as the volatile fallout, possibly because Ru activities were present in the fuel partly in the metallic state and partly as volatile oxides.

Accidents↗
PubMed1995

The variability in fallout content of soils and plants and the design of optimum field sampling strategies.

Sampling was carried out at an upland peat site in Ireland to assess the variability in 137Cs deposition to soils and activity concentration in individual vegetation species. A 3,600 m2 quadrat was laid out, and a soil core was extracted within each of sixteen 20 x 20 cm soil monoliths. The coefficient of variation values for 137Cs deposition and activity in individual soil horizons were in all cases greater than 30%, and the relative variability between corresponding horizons tended to increase with depth. Samples of Calluna vulgaris and Juncus squarrosus were taken at each soil sampling location and coefficients of variation for 137Cs activity in these species were 12 and 20%, respectively. The data was used to examine the relationship between the number of samples analyzed in a survey, the variability within those samples, and the way those two factors affect our ability to detect between-site differences in 137Cs contamination levels. A methodology is developed for detection of between-site differences in 137Cs contamination under different experimental criteria. The data show that, of the sample types examined, between-site differences could be detected most efficiently with C. vulgaris. Because of the variability associated with the 137Cs content of each sample type, between-site differences could be detected with fewer plant samples than soil samples. Plant-soil concentration ratios, transfer factors, and plant-plant ratios were calculated from the data, and the variability associated with each parameter was assessed. The variation among values for plant-plant ratios was less than among concentration ratios, and the greatest spread of values was associated with plant-soil transfer factors.

Analysis of Variance↗
PubMed2004

Effect of different methods of thermotherapy on skin microcirculation.

OBJECTIVE: The purpose of the study was to compare the effects of different methods of thermotherapy on skin microcirculation, skin temperature, and core temperature in patients with rheumatoid arthritis and in healthy persons. DESIGN: In 20 patients with rheumatoid arthritis and 20 healthy controls, the skin microcirculation was measured by means of laser-Doppler flowmetry before, at the end of, and 30 mins after completion of local thermotherapy (infrared light, paraffin, peat) in the lumbar area. In addition, skin and core temperature were recorded at the same point in time. The influence of previous intake of acetylsalicylic acid on skin microcirculation during thermotherapy was investigated. The controlled trial was conducted in an air-conditioned laboratory. RESULTS: All methods caused a significant increase in skin microcirculation (flow and vasomotion), skin temperature, and core temperature. The skin temperature showed the highest increase when infrared light was applied. The microcirculation became more intense when paraffin fango was used. There were no differences between the reactions of rheumatoid arthritis patients and healthy persons. The additional intake of 500 mg acetylsalicylic acid before treatment did not affect skin temperature or skin microcirculation. A tendency toward a sinusoidal rhythmization of vasomotion was detected. CONCLUSIONS: The effects of the three methods of thermotherapy differ quantitatively due to their physical attributes. The effects on circulation differ depending on the method chosen, and this is significant when selecting the least stressful method for a particular patient. Rheumatoid arthritis patients and healthy controls have the same increase of skin microcirculation in the lumbar area. Findings in the distal limbs might differ. All used therapies cause a rhythmization of the vasomotion and, as a consequence, a qualitative improvement of the microcirculation.

Adult↗
PubMed2006

Paedocypris, a new genus of Southeast Asian cyprinid fish with a remarkable sexual dimorphism, comprises the world's smallest vertebrate.

Paedocypris is a new genus of paedomorphic cyprinid fish from highly acidic blackwater peat swamps in Southeast Asia. It includes two new species, one of which (Paedocypris progenetica) appears to be the smallest fish and vertebrate known, with the smallest mature female measuring a mere 7.9 mm. Paedocypris has many 'larval' features typically associated with paedomorphic fish (e.g. narrow frontals that leave the brain unprotected dorsally by bone and a precaudal larval-fin-fold), but, uniquely among fishes, males also possess highly modified pelvic fins with hypertrophied muscles and a keratinized pad in front of the pelvic girdle, which, we hypothesize, function together as a clasping or holding device, thereby suggesting an unusual reproductive mode. Unfortunately, habitat destruction jeopardizes the survival of these fishes and thus opportunities for further research.

Animals↗
PubMed1980

Late Pleistocene deposits at Wing, Rutland.

The context, lithostratigraphy and biostratigraphy of a series of Pleistocene deposits from Wing, Rutland, in the East Midlands of England are described. The sequence of till, lake clays, compressed wood and moss peats and peaty silts is shown to occupy a small, closed basin cut deeply into the Jurassic bedrock. The basin appears to have been excavated by ice responsible for the deposition of Chalky Jurassic Till in the area, and this till lines the floor and sides of the basin. Pollen and plant macrofossil analyses have provided a long and continuous record of vegetational and environmental history at the site and the deposits have been dated by pollen analysis to the Last (Ipswichian) Interglacial and early Devensian Glacial stages (pollen zones Ip IIb to e De). With certain reservations, the sequence is compared and correlated with other interglacial deposits in Britain.

England↗
PubMed1998

Verrucosispora gifhornensis gen. nov., sp. nov., a new member of the actinobacterial family Micromonosporaceae.

A Gram-positive, aerobic, spore-forming actinomycete strain, HR1-2T, was isolated from a peat bog near Gifhorn, Lower Saxony, Germany. Comparative analysis of the 16S rDNA sequence indicated that HR1-2T was phylogenetically related to members of the family Micromonosporaceae, branching adjacent to Spirilliplanes yamanashiensis, Couchioplanes caeruleus, Catenuloplanes japonicus and members of the genus Micromonospora. The affiliation to the family was supported by the presence of family-specific 16S rDNA signature nucleotides, DNA G + C content of 70 mol%, peptidoglycan of type A1 gamma' (directly crossed-linked, presence of glycine, alanine, glutamic acid and mesodiaminopimelic acid in the peptide side-chain), menaquinone MK-9(H4) as the major respiratory lipoquinone, polar lipid composition PII (phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylserine and phosphatidylinositolmannosides) and a glycolyl type of muramic acid. It differed from genera of the family by the lack of arabinose in whole-cell sugars and a unique nucleotide signature stretch between positions 1132 and 1143 (Escherichia coli numbering), 5' CAAUUCGGUUG 3'. Morphologically strain HR1-2T resembles Micromonospora species but can be distinguished from them by the lack of arabinose in whole-cell sugars, the presence of 10-methyl C17:0 fatty acids and a distinct 16S rDNA sequence. Based on the unique combination of morphological, chemotaxonomic and phylogenetic properties a new genus, Verrucosispora gen. nov., is proposed. The type species of this genus is Verrucosispora gifhornensis sp. nov., and the type strain of V. gifhornensis is strain HR1-2T (= DSM 44337T).

Anti-Bacterial Agents↗
PubMed2000

Clostridium akagii sp. nov. and Clostridium acidisoli sp. nov.: acid-tolerant, N2-fixing clostridia isolated from acidic forest soil and litter.

Two anaerobic acid-tolerant bacteria, CK58T and CK74T, were isolated from acidic beech litter and acidic peat-bog soil, respectively. Both bacteria were spore-forming, motile rods with peritrichous flagella. The capacity to sporulate decreased with prolonged cultivation. Cells of CK58T formed chains or aggregates and were linked by a connecting filament that consisted of a core and a surrounding sheath. Cellobiose, glucose, xylose, arabinose, maltose, mannose and salicin supported growth of CK58T. These substrates, as well as mannitol, lactose, sucrose, glycerol, melezitose, raffinose and rhamnose, supported growth of CK74T. Sorbitol, trehalose, H2/CO2, CO/CO2, vanillate, Casamino acids, peptone, and various purines and pyrimidines did not support the growth of either organism. Growth of CK58T and CK74T on glucose yielded butyrate, lactate, acetate, formate, H2 and CO2 as end products. Growth of CK58T and CK74T was observed at pH 3.7-7.1 and 3.6-6.9, respectively. CK58T and CK74T grew in nitrogen-free medium at pH 3.7 under an N2 atmosphere and reduced acetylene at rates approximating 1 nmol min-1 (mg protein)-1. CK58T and CK74T did not contain carbon monoxide dehydrogenase or cytochromes, produce methane, or dissimilate nitrate or sulfate. Thus, CK58T and CK74T were characterized as nonacetogenic, N2-fixing, fermentative chemo-organotrophs. The G + C contents of CK58T and CK74T were 31.4 and 30.7 mol%, respectively. CK58T and CK74T were phylogenetically most closely related to Clostridium pasteurianum. The 16S rRNA gene sequence similarity values of CK58T and CK74T to C. pasteurianum and each other did not exceed 96.5%, and it is proposed that strains CK58T and CK74T be named Clostridium akagii CK58T (DSM 12554T) and Clostridium acidisoli CK74T (DSM 12555T), respectively. These results suggest that previously uncharacterized clostridial species reside and might fix N2 in the annoxic microzones of acidic forest soil and litter.

Anaerobiosis↗
PubMed2002

Methylocapsa acidiphila gen. nov., sp. nov., a novel methane-oxidizing and dinitrogen-fixing acidophilic bacterium from Sphagnum bog.

A novel genus and species, Methylocapsa acidiphila gen. nov., sp. nov., are proposed for a methane-oxidizing bacterium isolated from an acidic Sphagnum peat bog. This bacterium, designated strain B2T, represents aerobic, gram-negative, colourless, non-motile, curved coccoids that form conglomerates covered by an extracellular polysaccharide matrix. The cells use methane and methanol as sole sources of carbon and energy and utilize the serine pathway for carbon assimilation. Strain B2T is a moderately acidophilic organism with growth between pH 4.2 and 7.2 and at temperatures from 10 to 30 degrees C. The cells possess a well-developed system of intracytoplasmic membranes (ICM) packed in parallel on only one side of the cell membrane. This type of ICM structure represents a novel arrangement, which was termed type III. The resting cells are Azotobacter-type cysts. Strain B2T is capable of atmospheric nitrogen fixation; it possesses particulate methane monooxygenase and does not express soluble methane monooxygenase. The major phospholipid fatty acid is 18:1omega7c and the major phospholipids are phosphatidylglycerols. The G+C content of the DNA is 63.1 mol%. This bacterium belongs to the alpha-subclass of the Proteobacteria and is most closely related to the acidophilic methanotroph Methylocella palustris KT (97.3% 16S rDNA sequence similarity). However, the DNA-DNA hybridization value between strain B2T and Methylocella palustris K(T) is only 7%. Thus, strain B2T is proposed to comprise a novel genus and species, Methylocapsa acidiphila gen. nov., sp. nov. Strain B2T (= DSM 13967T = NCIMB 13765T) is the type strain.

Bryopsida↗
PubMed2006

Actinocatenispora thailandica gen. nov., sp. nov., a new member of the family Micromonosporaceae.

Two actinomycete strains, TT2-10(T) and TT2-3, which produced long spore chains (more than 10 spores per chain), were isolated from peat swamp forest soil in Pattaloong Province, Thailand. Their taxonomic positions were determined using a polyphasic approach. The chemotaxonomic characteristics of these strains coincided with those of the family Micromonosporaceae, i.e. cell-wall chemotype II, muramic acid of the N-glycolyl type, whole-cell sugar pattern D and type II phospholipids. Analysis of the 16S rRNA gene sequences also indicated that these strains constitute a distinct lineage within the family Micromonosporaceae, sharing 91.3-93.8 % sequence similarity with members of this family. On the basis of their phenotypic and genotypic characteristics and their phylogenetic position, these strains represent a novel genus and species, for which the name Actinocatenispora thailandica gen. nov., sp. nov. is proposed. The type strain of Actinocatenispora thailandica is strain TT2-10(T) (=JCM 12343(T)=PCU 235(T)=DSM 44816(T)).

Carbohydrates↗
PubMed2006

Isolation of aerobic, gliding, xylanolytic and laminarinolytic bacteria from acidic Sphagnum peatlands and emended description of Chitinophaga arvensicola Kampfer et al. 2006.

Four aerobic, heterotrophic, yellow-pigmented and flexirubin-producing bacterial strains with gliding motility were isolated from acidic Sphagnum-dominated wetlands of Northern Russia. These bacteria are capable of degrading xylan, laminarin and some other polysaccharides, but not cellulose, pectin or chitin. The four strains possess almost identical 16S rRNA gene sequences and are most closely related (98.9-99.5 % sequence similarity) to the recently reclassified species of the phylum Bacteroidetes, Chitinophaga arvensicola Kämpfer et al. 2006, formerly known as [Cytophaga] arvensicola Oyaizu et al. 1983. However, the novel isolates from Sphagnum peat differed from C. arvensicola DSM 3695(T) in their ability to degrade xylan and starch, by greater tolerance of acidic pH and by their inability to reduce nitrate. An emended description of this species is proposed.

Bacteria, Aerobic↗
PubMed2001

Derivation and mapping of critical loads for nitrogen and trends in their exceedance in Germany.

The term "critical load" means a quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur, according to present knowledge. In the case of nitrogen, both oxidised and reduced compounds contribute to the total deposition of acidity, which exceeds critical loads in many forest ecosystems. These also cause negative effects through eutrophication. Critical loads of nitrogen were derived for forest soils (deciduous and coniferous forest), natural grassland, acid fens, heathland, and mesotrophic peat bogs. In Germany, a decrease in sulphur emissions over the past 15 years resulted in a reduced exceedance of critical loads for acid deposition. In the same period it was noted that reduction in the emissions of nitrogen oxides and ammonia remained insignificant. Therefore, emissions of nitrogen compounds have become relatively more important and will continue to threaten ecosystem function and stability. The risk of environmental damage remains at an unacceptable level. The German maps show the degree to which the critical loads are exceeded, and they present current developments and an expected future trend. Results indicate that recovery from pollutant stress occurs only gradually.

Ecosystem↗
PubMed2004

Phosphatase under-producer mutants have altered phosphorus relations.

Phosphorus (P) acquisition and partitioning are essential for plant homeostasis. P is available for plant uptake when in its inorganic form (H2PO4-, or Pi), but Pi is often limiting in soils. Plants secrete acid phosphatases (APases) into the apoplastic space, which may be important for obtaining Pi from organic P sources; however, the relative importance of these enzymes for plant P nutrition has yet to be determined. We demonstrate that the root-associated APase pool is increased in Arabidopsis when Pi is limiting and document five APase isoforms secreted from Arabidopsis roots. Previously, we presented the identification of the phosphatase under-producer (pup) mutants, which have decreased in vivo root APase staining when grown under low P conditions. Here, we present the characterization of one of these, pup3, and further studies with pup1. pup3 has 49%, 38%, and 37% less specific APase activity in exudates, roots, and shoots, respectively. Root-associated APase activity is decreased by 16% in pup1 and 25% in pup3, regardless of P treatment. Two APase activity isoforms are reduced in pup3 exudates, and root and shoot isoforms are also affected. One of the two exudate isoforms is recognized by a polyclonal antibody raised to an Arabidopsis purple APase recombinant protein (AtPAP12); however, AtPAP12 transcript levels are unaffected in the mutant. The pup3 mutation was mapped to 68.4 +/- 6.0 centimorgans on chromosome 5. Although P concentrations were not altered in pup1 and pup3 tissues when grown in nutrient solution in which Pi was the sole source of P, the mutants had 10% (pup1) and 17% (pup3) lower shoot P concentrations when grown in a peat-vermiculite mix in which the majority of the total P was present as organic P. Therefore, the pup defects, which include secreted APases, are functionally important for plant P nutrition.

Acid Phosphatase↗
PubMed1981

Stomatal Response and Leaf Injury of Pisum sativum L. with SO(2) and O(3) Exposures : II. INFLUENCE OF MOISTURE STRESS AND TIME OF EXPOSURE.

Stomatal response during exposure to SO(2) and O(3) and subsequent leaf injury were examined in plants of Pisum sativum L. ;Alsweet' grown in a peat-vermiculite medium in controlled environment chambers. Plants developing under moisture stress, induced by drying the medium to 50% of field capacity, exhibited greater stomatal closure during exposures and less than one-fourth the necrosis compared to plants developing in a medium maintained at field capacity. Plants under moisture stress had only a slightly more negative plant water potential ( approximately -4.0 bars) than at field capacity ( approximately -3.4 bars). Plants exposed to pollutants for 2 hours near the beginning or end of a 16-hour light period had greater stomatal closure during exposures and less leaf necrosis than plants exposed during the middle of the light period.

Journal Article↗