Translocation Of 32P Research Articles

Contribution of legumes on phosphoric absorption by Panicum maximum cv Riversdale in intercropping system

Phosphorus availability in soil as a mobile mineral influences forage growth. The purpose of doing this research is to enhance the soil phosphorus availability and grass production of Panicum maximum cv Riversdale by intercropping system with legums. The experiment was conducted based on with randomized design with five treatments of mixcropping of: (i) Gliricidia sepium + P. maximum; (ii) Calliandra calothyrsus + P. maximum; (iii) Leucaena leucocephala cv Taramba + P. maximum; (iv) Calopogonium mucunoides + P. maximum; (v) P. maximum as negative control. Plants were grown in pots with split-root technique using partition with a whole to allow some legume roots grew in the grass side. After growing for three months, on the legume areas 32P isotop solution was injected for 50 ml (11.23 μci/ml). After 21 days incubation samples were collected from both soil areas and both plants. The translocation of 32P was determined using geiger counter from legumes into the grass and the concentration of 32P was also determined in all plants. Forage productions was determined both in the legumes and grass. Result showed that soil phosphorus concentration in the grass area was significantly improved by intercropping with G. sepium and C. callothyrsus, while the one with L. leucocephala was similar, and the one with C. mucunoides was significantly lower than that of negative control (without legume). Detection of 32P showed that there was P translocation in the system. P. maximum grass production depending on kind of legumes (P<0.05) those with G. sepium was significantly higher, L. leucocephala and C. callothyrsus were not significantly higher, while the one with C. mucunoides was 26.2% lower from the control although not significantly. However, C. mucunoides produced the highest forage from the legume plant. It is concluded that grass-legume intercropping had a positive impact on phosphorus soil concentration in the grass area and grass production. Kind of legumes influenced the effectivity.

Anatomy and Functional Status of Haustoria in Field Grown Sandalwood Tree (<i>Santalum album</i> L.)

A study on the physiology of root parasitism in sandal ( Santalum album L.) was conducted by comparing a six-year-old sandal grown alone and along with a host ( Casuarina equisetifolia ). Although maximum haustorial connections were observed when grown along with the host, sandal formed haustorial connections with plants including grass up to a distance of 3 m. Anatomical studies on haustoria indicated a vascular connectivity between the host and sandal. While the haustoria functioned as a physiological unit supporting nutritional requirements of sandal, direct lumen-lumen xylem connections between sandal and host were absent. Functional status of the haustorial connection was studied by radio-labelling the host ( Casuarina ) and nearby grass with phosphorus ( 32 P). Presence of translocated 32 P in sandal was noticed after six hours of labelling the host. 32 P activity was noticed from eight days up to 16 days after which then it started decreasing. Study with multiple hosts revealed that the extent of translocation from hosts to sandal varied from 28.9% (coconut + Casuarina + rubber as host) to 78.5% ( Casuarina + rubber as hosts). Reverse translocation of 32P from sandal to host was also observed. The study concludes that it is not necessary to plant the host along with the sandal as it is practiced presently.

Translocation of 32P from leaves to seeds of sunflower and associated biochemical changes in young and mature leaves during seed-filling

Transport of <sup>32</sup>P from mature leaves was studied at stage I (ray florets opening), stage II (50% florets opening) and stage III (central disc florets opening) of the capitulum in order to ascertain the capacity of developing seeds to draw metabolites. Experiments showed that when feeding was done at stage I separately in the 6th, 7th and 8th leaf from the apex, accumulation of <sup>32</sup>P was maximum in the peripheral seeds of the corresponding zone of the fed leaf. Also at stage II was <sup>32</sup>P accumulation high in the peripheral zone along with high accumulation in the inner zone. But at stage III and IV (seven days after central disc florets opening) when accumulation declined considerably in the peripheral zone, very little accumulation of <sup>32</sup>P was noted in the central zone of the capitulum. During maximum sink demand i.e. at stage II, the soluble cabohydrate level increased both in apically borne young and mature leaves but declined thereafter only ,in mature leaves. In both young and mature leaves the chlorophyll level, however, did not show any decline even at stage IV, It was further observed that dry matter retention capacity declined only in young leaves from stage II onwards. In young leaves, catalase activity was low from stage II whereas in mature leaves it was low at stage II followed by a transient sharp increase at stage III.

Real-time imaging of ion uptake from root to above-ground part of the plant using conventional beta-ray emitters

We present real-time imaging of 32P-phosphate within a living plant as well as that in culture solution toward roots. The above-ground part of the plant was irradiated with light from LED and roots were kept in dark. The plant was Lotus japonicus, cv. Miyakojima MG20 and real-time 32P-phosphate uptake manners in young, flowering and adult phase were visualized. In the case of young plant, there was a preferential translocation of 32P in younger leaves. When the sample was treated with phosphate deficient condition, 32P uptake amount was much higher. In an adult phase, 32P uptake was high at pods.

Real-time Imaging of 32P Translocation in Soybean Plants

リン酸は，植物のリン酸栄養環境応答時の認識機構に関わる重要な因子である。そこで，植物体内のリン酸吸収移行の特徴について知るためにリン酸欠乏下のダイズを用い32Pトレーサ実験を行った。トレーサ実験では，従来のImaging Plateと，リン酸の速い動きを定量的にイメージングできるリアルタイムRIイメージングシステムを用いた。その結果，リン酸は通常条件で栽培した場合には常に新葉への移行が古い葉への移行よりも約3倍高くなるのに対して，リン酸欠乏環境下では古い葉へも積極的に移行することが示された。

Real-time imaging of radioisotope labeled compounds in a living plant

We developed a quantitative, real-time imaging system of labeled compounds in a living plant. The system was composed of CsI scintillator to convert β-rays to visible light and an image intensifier unit (composed of GaAsP semiconductor and MCP; micro channel plate) to detect extremely weak light. When the sensitivity and resolution of the image of our system was compared with that of an imaging plate (IP), the sensitivity of our system (with 20 minutes) was higher than that of an IP, with similar quality to that of an IP. Using this system, the translocation of 32P in a soybean plant tissue was shown in successive images.

Patterns and dynamics of 32P-phosphate and labelled 2-aminoisobutyric acid ( 14C-AIB) translocation in intact basidiomycete mycelia

Following uptake of 32P-orthophosphate and 14C-aminoisobutyric acid ( 14C-AIB) the patterns of distribution of the isotopes through intact basidiomycete mycelia were non-destructively mapped at regular intervals using a β-scanner. Analysis of the results suggests that translocation of 32P and 14C-AIB through mycelia of Pleurotus ostreatus and Schizophyllum commune occurred along a restricted number of clearly defined, but macroscopically invisible, routes through the mycelium. In contrast to this, 32P added to mycelia of Coprinus cinereus remained immobilised at the addition point. Simultaneous acropetal and basipetal translocation of 32P and 14C-AIB was observed in different regions of colonies of P. ostreatus and S. commune. Translocation of label around the periphery of colonies strongly suggested the existence of anastomoses around the colony margin. Both 32P and 14C-AIB were initially immobilised at the addition point, from which each was subsequently translocated to other parts of the mycelium. The observed translocation of nutrients could not be explained by simple diffusion alone. The velocity of translocation and the complexity of the translocation pattern of 32P were greatest in mycelia of P. ostreatus, a hardwood decomposer, followed by S. commune, a wood and litter decomposer and parasite. Translocation through mycelia of C. cinereus, a coprophilus saprophyte, was very slow. This study provides the first detailed description of nutrient translocation through intact, entire fungal mycelia over time.

Patterns and dynamics of 32P-phosphate and labelled 2-aminoisobutyric acid (14C-AIB) translocation in intact basidiomycete mycelia

Following uptake of 32P-orthophosphate and 14C-aminoisobutyric acid (14C-AIB) the patterns of distribution of the isotopes through intact basidiomycete mycelia were non-destructively mapped at regular intervals using a β-scanner. Analysis of the results suggests that translocation of 32P and 14C-AIB through mycelia of Pleurotus ostreatus and Schizophyllum commune occurred along a restricted number of clearly defined, but macroscopically invisible, routes through the mycelium. In contrast to this, 32P added to mycelia of Coprinus cinereus remained immobilised at the addition point. Simultaneous acropetal and basipetal translocation of 32P and 14C-AIB was observed in different regions of colonies of P. ostreatus and S. commune. Translocation of label around the periphery of colonies strongly suggested the existence of anastomoses around the colony margin. Both 32P and 14C-AIB were initially immobilised at the addition point, from which each was subsequently translocated to other parts of the mycelium. The observed translocation of nutrients could not be explained by simple diffusion alone. The velocity of translocation and the complexity of the translocation pattern of 32P were greatest in mycelia of P. ostreatus, a hardwood decomposer, followed by S. commune, a wood and litter decomposer and parasite. Translocation through mycelia of C. cinereus, a coprophilus saprophyte, was very slow. This study provides the first detailed description of nutrient translocation through intact, entire fungal mycelia over time.

Wood decay and phosphorus translocation by the cord‐forming basidiomycete Phanerochaete velutina: the significance of local nutrient supply

Mycelial cord systems of Phanerochaete velutina (DC.: Pers.) Parmasto grown from 4 cm3 inocula on a nutrient‐depleted non‐sterile soil in compartmentalized laboratory microcosms were baited after 13 d of growth with either fresh, non‐sterile 4 cm3 wood blocks or control Perspex® blocks of the same contact area. After 112 d, mature mycelial systems, which were in senescent phase, were subjected to disturbance by supplying a new fresh wood bait diametrically opposite the existing bait and, after 126 d, to nutrient regime amendment by application of NPK solution. At harvest (186 d) there was a significant (P0·001) linear relationship between extra‐resource mycelial biomass and total wood decay over the preceding 74 d. Nutrient amendment alone did not significantly (P>0·05) affect extra‐resource mycelial biomass production or wood decay rates in either disturbed or undisturbed cord systems. However, both mycelial biomass production and resource decay were significantly (P0·05) enhanced when nutrient amendment and disturbance treatments were applied concurrently. Bi‐directional phosphorus translocation to inocula and wood baits (determined non‐destructively) was assessed by labelling the NPK solution applied distal or proximal to the initially supplied bait with 32P. In both disturbed and undisturbed cord systems the rate of 32P uptake from a local supply was two orders of magnitude higher than from a distal supply. In disturbed cord systems uptake of 32P by inocula, which were midway between the two radiotracer supply points, was significantly (P0·05) higher when the supply point contained a newly supplied wood bait. Net translocation of 32P to newly supplied wood baits increased with time at the expense of translocation to inocula and existing wood baits. The switch in direction of net phosphorus translocation, the importance of localized nutrient scavenging and the partitioning of wood decay are discussed in relation to the ecological significance of mycelial cords.

Translocation of 32P between wood resources recently colonised by mycelial cord systems of Phanerochaete velutina

The basidiomycete fungus Phanerochaete velutina was inoculated centrally into trays of compressed, non-sterile woodland soil on precolonised 1 cm3 beech wood blocks. Mycelial systems developed from this and colonised two ‘baits’ (wood blocks or inert plastic controls), one on either side of the inoculum block. 32P-orthophosphate was supplied to a bait and its appearance in the other bait was monitored non-destructively with time, and destructively by liquid scintillation counting 60 or 70 days after addition of the radioisotope. Phosphorus was taken up by the first bait, translocated back to the inoculum block and onwards to the second bait. When the second bait was added 10 days after the first, translocation to the former was much more rapid indicating a large demand for phosphorus during early stages of colonisation. The size of the bait to which the 32P was added appeared to determine the amount taken up by the whole system, and the size of the second bait determined how much 32P was translocated to it. Decayed and/or small baits had less demand for phosphorous. The ecological relevance of these findings is discussed.

Translocation of 32P between wood resources recently colonised by mycelial cord systems of Phanerochaete velutina

Translocation of 32P between wood resources recently colonised by mycelial cord systems of Phanerochaete velutina

Uptake and translocation of prey‐derived 15N and 32P in Utricularia vulgaris L.

summaryThe rootless submerged carnivorous hydrophyte Utricularia vulgaris L. is a potentially useful subject for the quantitative study of foliar nutrient uptake and use, because known quantities of nutrients can be supplied precisely to individual leaves. We report here results obtained by hand‐feeding prey labelled with 15N and 32P to leaves of known age in plants growing in near‐natural conditions.Prey‐derived 15N was rapidly taken up and translocated: in plants fed via 3‐d‐old leaves, about 30% of the prey 1SN appeared in the immature parts of the plant within 2 d. Almost all parts of the plant that were immature at the time of feeding received and retained prey 15N throughout the 20 d experiment. Some backward translocation of 1SN was observed, but only up to the second day after feeding. 32P was also taken up and translocated rapidly, but was not retained by young tissues after they had become mature. Backward translocation of 32P was observed into side‐shoot meristems and flowers arising on parts of the plant older than the fed leaves. This is in contrast to 15N uptake, where side‐shoot buds and flowers received labelled nitrogen only if they arose on parts of the plant younger than the fed leaves.

External hyphae of vesicular—arbuscular mycorrhizal fungi associated with Trifolium subterraneum L.

summaryPhosphorus transport by hyphae of the three VA mycorrhizal fungi, Acaulospora laevis Gerdemann & Trappe, Glomus sp. and Scutellospora calospora (Nicol. & Gerd.) Walker & Sanders, associated with Trifolium subterraneum L. was investigated by means of radiotracer techniques. Plants with roots heavily colonized by each mycorrhizal fungus were transplanted to two‐compartment systems, where a hyphal compartment was separated from the main compartment by a fine mesh preventing root penetration. The hyphal compartment contained layers of 32P‐labelled soil, which were placed at 0, 1, 2.5, 4.5 or 7 cm from the root compartment.A time‐course study over 37 d showed that Glomus sp. transported most 32P to shoots over soil‐root distances shorter than 1 cm. In contrast, A. laevis transported most 32P to shoots over soil–root distances longer than 1 cm. This ability of A. laevis to transport phosphorus over longer distances than Glomus sp. parallels previous observations that hyphae of A. laevis spread faster and further in soil than hyphae of the Glomus sp. Scutellospora calospora transported much less 32P to plants, but accumulated more 32P in its hyphae, than the two other fungi. The higher specific radioactivity in the hyphae of S. calospora than of A. laevis and Glomus sp. indicated a retarded translocation of 32P in its hyphae or retarded transfer of 32P across its interface with the host. However, the poor phosphorus transport by S. calospora might also have resulted from its reaction to root trimming at transplanting; percentage root colonization by S. calospora decreased markedly after transplanting to the labelling system.

Phosphorus translocation in salt‐stressed cotton

The effect of salinity on plants has usually been studied at high inorganic P concentration ([Pi]) in the nutrient solution, and salinity × Pi interactions have been examined at much higher [Pi] than found in soil solutions. Short‐term 32Pi experiments were carried out to study the effect of salinity (150 mM NaCl) on phosphorus translocation in cotton plants (Gossypium hirsutum L. cv. Acala SJ‐2) grown in nutrient solutions containing 10 μM [Pi]. The effect of additional Ca to a concentration of 10 μM was also tested. Salinity inhibited 32P translocation from root to shoot. This inhibition was more evident at higher [Pi] in the root medium. Increasing [Pi] 33‐fold in the solution resulted in a 4.3‐fold increase in [32P] in the root under saline conditions, but only in a 1,8‐fold increase in the shoot. In older shoot tissues total [P] was elevated in the salinized plants. In the young tissues, however, total P concentration was higher in control plants. Inhibition of 32P translocation by salinity was greater from root to young leaves than to mature shoot tissues. Salinity also decreased 32P recirculation from the cotyledons to the young leaf. Inhibition by salinity of both 32P translocation and recirculation to young leaves was fully reversed by increasing Ca supply from 1 to 10

The fate of soil‐derived phosphorus in mycelial cord systems of Phanerochaete velutina and Phallus impudicus

SUMMARYThis study demonstrated the direct uptake of [32P]phosphorus from soil by ‘foraging’ cord systems of Phanerochaete velutina (DC: Pers.) Parmasto and Phallus impudicus (L.) Pers., grown from 4 cm3beech (Fagus sylvatica L.) wood inocula. Total uptake was independent of, but ‘allocation’ within cord systems dependent on, species, the state of decay of wood inocula, and phosphorus availability in different parts of cord systems. Cords were shown to be functional pathways for translocation of 32P between distant resource units and more than 90 % of accumulated phosphorus was translocated to the inocula or to new resource units. Allocation of opportunistically‐scavenged phosphorus was in preferential order of the potential of new resource units as carbon sources and in proportion to the mass of like resource units. Non‐destructive 32P determination, using a scintillation probe, showed that significant differences (P 0.05) in allocation to combinations of new resource units could be detected within 12 d and corresponded with the results of destructive total 32P determination after nine weeks. The results are discussed in terms of the role of saprotrophic cord‐forming basidiomycetes in nutrient cycling and the efficiency of nutrient allocation within their cord systems.

Root histology, and nutrient uptake and translocation in tissue culture plantlets and seedlings ofThuja occidentalis L.

Histological studies of the vascular connection in the root-shoot junction of tissue culture-derived plantlets and seedlings ofThuja occidentalis L. (Eastern white cedar) showed that in both plant types the xylem was well developed, smooth and not disrupted. Uptake and translocation of32P and86Rb were also similar for plantlets and seedlings. However, approximately 50% more86Rb could be desorbed from the root Donnan free space of plantlets than from seedlings. Uptake and translocation to the shoot was higher for86Rb than for32P, but no differences were found between the plant types. Tracer translocation rates to the shoot seem to be positively correlated with shoot fresh weight.

Physiology

Hign yielding F1 hybrid rice translocated 32P to their tillers more effectively than did their parents. Tiller number and 32P concentration in tillers were significantly correlated (r=0.61*). The regression of tiller numDer ana 32P distributed in tillers was Y=0.06x + 1.18. The 35S translocated and distributed in tillers and panicles of F1 hybrid rice was not positively correlated with grain yield. Translocation of 32P, 35 S and 14C‐glucoses to panicles of a male sterile line was lower than in the F1 hybrid and showed a progressive decline between the booting and milky stages. Tnis represents a metabolic disorder associated witn male sterility.

Effect of aluminum on 32P uptake and translocation by red spruce seedlings

32P uptake and translocation was simultaneously studied in 11-week-old red spruce (Picearubens Sarg.) seedlings that had been pretreated for 24 h in hydroponic culture with or without 10 mg Al L−1. Aluminum in solution enhanced the accumulation of 32P in roots by more than two orders of magnitude over uptake in control seedlings, while the translocation of 32P to apical buds and mature primary needles was reduced to 20.0 and 9.1% of control levels, respectively. Kinetic analysis of 32P uptake indicated that P absorption is mediated by an uptake system exhibiting Michaelis–Menten behavior from solutions ranging from 0.01 to 5.00 mM KH2PO4; uptake at 10.0 mM KH2PO4 was inconsistent with this model. Changes in the patterns of 32P uptake and translocation in seedlings treated with Al suggest that Al in solution altered accumulation processes.

PHOSPHATE UPTAKE BY GOODYERA REPENS IN RELATION TO MYCORRHIZAL INFECTION

SummaryThe rate of P uptake per unit length of root of adult plants of the orchid Goodyera repens Br., infected with the mycorrhizal endophyte Rhizoctonia goodyerae‐repentis Constantin and Dufour, was up to 100 times greater than that of non‐mycorrhizal plants. When the active extramatrical mycelium was reduced by treatment with thiabendazole fungicide, the relative growth rate of mycorrhizal plants was reduced in low P conditions but not in P rich conditions. Rates of P uptake into fungicide‐treated plants were Jess than those of mycorrhizal plants at both P levels. Translocation of 32P from a point source to the plant via the extramatrical mycelium was demonstrated and could be inhibited by the application of thiabendazole. In a model system incorporating a perlite/Vermiculite substrate, translocation of 32P via the endophyte took place over distances up to 9 cm. The mycorrhiza of adult G. repens appears similar to other mycorrhizas in its ability to enhance growth and P uptake.

Pathway and regulation of phosphate translocation to the pods of soybean explants

We investigated the degree to which developing fruit compete directly with leaves for mineral nutrients, e.g. phosphate coming up from the roots. When soybean (Glycine max (L.) Merrill cv. Anoka) explants cut at mid‐late podfill were given a 15‐min pulse of 32Pi via the cut stem and then transferred to distilled water, 75% of the 32P accumulated in the leaves and 21% in stem and petiole during the first hour. The amount of 32P entering the seeds was low (1%) initially, but thereafter increased to 30% in 48 h. An accumulation of 32P in the seed coats preceded its entry into the embryos. Disruption (with hot steam) of the phloem between the leaf and the pods after pulse labelling indicated that more than 80% of the 32Pi pulse moved to the leaf before redistribution to the pods. Increasing “sink” size by adjusting the pod load from 1 to 2–3 did not increase the 32P accumulated by the pods proportionally. Conversely, excision of the seeds after pulse labelling did not prevent translocation of 32P out of the leaves. These results suggest that the rate of transport of phosphate to the pods at mid‐late podfill is controlled primarily by factors in the leaves. The results are consistent with the observation that the relative size of the sink (pod load) does not regulate leaf senescence.