Leaf Phosphate Research Articles

Effects of Extreme Drought and Heat Events on Leaf Metabolome of Black Alder (Alnus glutinosa L.) Growing at Neighboring Sites with Different Water Availability

Riparian tree species are thought to be sensitive to the more frequent and intensive drought and heat events that are projected to occur in the future. However, compared to waterlogging, information about the responses of these tree species to water limitation and heat is still scare. Black alder (Alnus glutinosa L.) is a riparian tree species with significant ecological and economic importance in Europe. In the present study, we investigated the physiological responses of black alder (Alnus glutinosa L.) to different water availabilities growing at neighboring sites. Compared to trees with unlimited water source, trees with a limited water source had 20% lower leaf hydration, 39% less H2O2 contents, and 34% lower dehydroascorbate reductase activities. Concurrent with dramatically accumulated glutathione and phenolic compounds, leaf glutathione contents were two times higher in trees with limited water than in trees with sufficient water. Limited water availability also resulted in increased abundances of sugars, sugar acids, and polyols. Serine, alanine, as well as soluble protein related to nitrogen metabolism were also accumulated under limited water conditions. In contrast to sulfate, leaf phosphate contents were significantly increased under limited water. No significant effects of water conditions on malondialdehyde and ascorbate contents and fatty acid abundances were observed. The present study improves our understanding of the physiological responses of black alder to different water conditions. Our findings highlight this riparian species is at least to some extent resistant to future drought with a well-regulated system including antioxidative and metabolic processes and its potential as an admixture candidate for afforestation in either water-logged or dry areas, particularly in nitrogen limited habitats.

Downregulation of GeBP-like \u03b1 factor by MiR827 suggests their involvement in senescence and phosphate homeostasis

BackgroundLeaf senescence is a genetically controlled degenerative process intimately linked to phosphate homeostasis during plant development and responses to environmental conditions. Senescence is accelerated by phosphate deficiency, with recycling and mobilization of phosphate from senescing leaves serving as a major phosphate source for sink tissues. Previously, miR827 was shown to play a significant role in regulating phosphate homeostasis, and induction of its expression was also observed during Arabidopsis leaf senescence. However, whether shared mechanisms underlie potentially common regulatory roles of miR827 in both processes is not understood. Here, we dissect the regulatory machinery downstream of miR827.ResultsOverexpression or inhibited expression of miR827 led to an acceleration or delay in the progress of senescence, respectively. The transcriptional regulator GLABRA1 enhancer-binding protein (GeBP)-like (GPLα) gene was identified as a possible target of miR827. GPLα expression was elevated in miR827-suppressed lines and reduced in miR827-overexpressing lines. Furthermore, heterologous co-expression of pre-miR827 in tobacco leaves reduced GPLα transcript levels, but this effect was eliminated when pre-miR827 recognition sites in GPLα were mutated. GPLα expression is induced during senescence and its inhibition or overexpression resulted in senescence acceleration and inhibition, accordingly. Furthermore, GPLα expression was induced by phosphate deficiency, and overexpression of GPLα led to reduced expression of phosphate transporter 1 genes, lower leaf phosphate content, and related root morphology. The encoded GPLα protein was localized to the nucleus.ConclusionsWe suggest that MiR827 and the transcription factor GPLα may be functionally involved in senescence and phosphate homeostasis, revealing a potential new role for miR827 and the function of the previously unstudied GPLα. The close interactions between senescence and phosphate homeostasis are further emphasized by the functional involvement of the two regulatory components, miR827 and GPLα, in both processes and the interactions between them.

Biotechnological mechanism for improving plant remobilization of phosphorus during leaf senescence.

SummaryPhosphorus enrichment of aquatic ecosystems through diffuse source pollution is an ongoing issue worldwide. A potential solution lies in the use of fast‐growing, multipurpose feedstocks, such as trees, to limit the flow of phosphorus into riparian areas through luxury consumption. However, the perennial nature of trees and their use of leaves as storage organs for excess phosphorus may reduce the effectiveness of contaminant removal during periods of leaf abscission. In an attempt to improve phosphorus remobilization during autumnal senescence, transgenic hybrid poplar P39 (Populus alba × Populus grandidentata) and Arabidopsis thaliana harbouring a constitutively expressed low‐affinity potato phosphate transporter (35S::StPht1‐1) were generated using Agrobacterium‐mediated transformation. For both species, the highest expressing 35S::StPht1‐1 lines were grown alongside wild‐type plants and subjected to increasing phosphate applications. StPht1‐1 expression in A. thaliana led to a reduction in biomass when grown under high‐phosphate conditions and had no effect on phosphate remobilization during senescence. In contrast, StPht1‐1 constitutive expression in P39 resulted in increased leaf phosphate content in the highest expressing transgenic line and minimal to no effect on P resorption efficiency. Surprisingly, sulphate resorption showed the greatest improvement in all three transgenic poplar lines, displaying a 31%–37% increase in resorption efficiency. These results highlight the complexity of nutrient resorption mechanisms in plants.

Pseudomonas putida improved soil enzyme activity and growth of kasumbha under low input of mineral fertilizers

ABSTRACTEffective management of the nutrients and enzyme activity in the soil is necessary for maximum crop growth and productivity. However, the excessive use of chemical fertilizers (CFs) not only adversely affects the soil nutrient status and soil physicochemical properties but also aids pollution to the ecosystem. The objective of present study was to investigate the effect of single as well as combined applications of phosphate-solubilizing bacteria and agrochemicals on important soil enzyme activities and their impact on the growth of kasumbha (safflower). Pseudomonas putida (P. putida;106 cells/mL) was applied as seed inoculation prior to sowing, and CFs were applied as full, half, and quarter doses during sowing to modulate the growth of kasumbha host plants. P. putida in combination with half dose of CFs (PH) increased the soil urease and phosphatase activities, while P. putida combined with quarter dose of CFs (PQ) augmented the soil invertase activities. Moreover, the PQ treatment exhibited the maximum colony-forming units of P. putida. Leaf chlorophyll, carotenoids, protein contents, and root lengths were increased by PH treatment. Whereas, shoot length and leaf area were improved by PH and PQ treatments, respectively. Leaf protease activity was enhanced by P. putida in combination with full dose of CFs and PQ treatments, while leaf phosphate contents were significantly improved by PQ treatment. It can be concluded that P. putida in combination with half as well as quarter doses of CFs is a promising approach for the improvement of soil enzyme activities and growth of kasumbha and replacing 50% of the use of CFs.

Effects of nitrogen and phosphate fertilization on leaf nutrient content, photosynthesis, and growth of the novel bioenergy crop Fallopia sachalinensis cv. 'Igniscum Candy'.

The aim of the study was to determine the effects of nitrogen and phosphate fertilization on the growth performance of the novel bioenergy crop Fallopia sachalliensis cv. ‘Igniscum Candy’ (Polygonaceae). In a controlled pot experiment various nitrogen (0, 50, 150, 300 kg N ha-1) and phosphate (20, 40, 80 kg P ha-1) fertilizer amounts were applied to measure the effect on the biomass, height, leaf area and nitrogen and phosphate use efficiency. Furthermore, ecophysiological processes (chlorophyll content, chlorophyll fluorescence, gas exchange) were measured with non-destructive methods. The application of nitrogen correlated positively with biomass production, while phosphate fertilization did not show a significant effect on plant growth or ecophysiological parameters. The leaf nitrogen contents were significantly correlated with the nitrogen applications, while the leaf phosphate contents did not show a correlation with the P fertilizations, but increased with the leaf nitrogen contents. A significant linear correlation between the measured SPAD values and chlorophyll contents as well as with the leaf nitrogen contents could be determined. Under the influence of the nitrogen fertilization, net photosynthesis increased from 3.7 to 6.6 μmol m-2 s-1. The results of this experiment demonstrated that nitrogen fertilization has an overall positive correlation with leaf nutrient content, photosynthesis, and overall growth of the bioenergy crop Fallopia sachalinensis var. Igniscum Candy.

Evaluation of Spent Mushroom Substrate as biofertilizer for growth improvement of Capsicum annuum L.

Influence of spent mushroom substrate (SMS) of oyster mushroom and button mushroom on the improvement of health status of Capsicum annuum L. was investigated. Analysis of growth promotion in terms of height, no of branches, yield and no of leaf drop indicated that the use of the spent mushroom substrate of oyster mushroom and spent compost of button mushroom had a positive effect on the overall growth of the tested plants. SMS had a role in mobilizing the soil phosphate which was evident by a decrease in soil phosphate level and increase in root and leaf phosphate following treatment with SMS. Chlorophyll content of plants increased when treated with oyster mushroom fresh substrate and button mushroom leachate compost. Fruits of plants treated with button mushroom leachate compost and oyster mushroom fresh substrate showed an increase in protein content of about 2.5 times over control. Similarly, carotenoid contents of fruits also increased significantly in the treated plants, but increases in leaves were not significant. It is evident from the present study that the use of different form of spent mushroom substrate of oyster mushroom and spent compost of button mushroom led to the overall increase in growth of Capsicum annuum L.

Establishment of a shortened annual cycle system; a tool for the analysis of annual re-translocation of phosphorus in the deciduous woody plant (Populus alba L.)

The supply of phosphorus, the essential element for plant growth and development, is often limited in natural environments. Plants employ multiple physiological strategies to minimize the impact of phosphate deficiency. In deciduous trees, phosphorus is remobilized from senescing leaves in autumn and stored in other tissues for reuse in the following spring. We previously monitored the annual changes in leaf phosphate content of white poplar (Populus alba) growing under natural conditions and found that about 75 % of inorganic and 60 % of organic leaf phosphates observed in May were remobilized by November. In order to analyze this process (such annual events), we have established a model system, in which an annual cycle of phosphate re-translocation in trees can be simulated under laboratory conditions by controlling temperature and photoperiod (='shortened annual cycle'). This system evidently allowed us to monitor the annual changes in leaf color, phosphate remobilization from senescent leaves, and bud break in the next spring within five months. This will greatly facilitate the analysis of cellular and molecular mechanisms of annual phosphate re-translocation in deciduous trees.

Exploring phosphate effects on leaf flammability using a physical chemistry model

Some plants have traits that cause them to be more flammable than others, influencing wildfire spread and fire regimes. Some of these plant traits have been identified through laboratory-scale experiments. We built a numerical model that could quantify the extent of these effects on flammability. Here we present that model and use it to investigate the effect of phosphate content on the flammability of leaves. The model used finite-element methods and was based on heat transfer and thermal decomposition kinetics. Predictions were compared with three laboratory experiments involving ignition of leaf or cellulose samples. We then ran simulations of two situations through which leaf phosphate could influence wildfire spread: horizontal fire spread and crowning. The ignition time and maximum fuel gap that could be bridged by a flame front was predicted. Two key results emerged. (1) The importance of leaf phosphate in laboratory studies of ignition depends on the rate of sample heating, with the strongest effect under slow heating. (2) In the context of wildfires, phosphate was predicted to have modest effects compared with other plant traits influencing moisture content, leaf construction and angle of display.

Influence of Serratia marcescens TRS-1 on growth promotion and induction of resistance in Camellia sinensis against Fomes lamaoensis

Serratia marcescens (TRS-1), either as aqueous suspensions or in bioformulations of sawdust, rice husk and tea waste, promoted growth in tea seedlings as evidenced by increase in height, emergence of new leaves and branches, as well as increase in leaf biomass. Survival of S. marcescens in soil after application was determined by ELISA and Dot-Blot using PAb raised against the bacterium. S. marcescens solubilized phosphate in vitro and in vivo. Following application of the bacterium, soil P content decreased, root and leaf phosphate increased, and soil phosphatase activities were enhanced. The bacterium was antagonistic to a number of fungal pathogens in vitro. It also reduced brown root rot of tea caused by Fomes lamaoensis. Significant increase in phenolics, as well as peroxidase, chitinase, β-1,3-glucanase and phenylalanine ammonia-lyase, were observed in tea plants on application of S. marcescens alone or followed by F. lamaoensis.

Synergic effects of VAM and polyphenoloxidases on increased productivity of brinjal and tomato in relation to resistance against fusarial wilt

Influence of an endomycorrhizal species Glomus fasciculatum on the growth of two vegetable plants, namely, Solanum melongena and Lycopersicon esculentum and for reduction of the incidence of fusarial wilt disease under field condition was studied. VAM treated plants showed more vigor in terms of productivity parameters viz., plant height, number of branching twigs and fruit production. VAM and pathogen treated plants also showed positive effect of VAM-symbiont over control indicating reduction of pathogenic stress of the plant and give resistance. Leaf phosphate, chlorophyll content and percentage of mycorrhization were recorded highest when plants were singly inoculated with Glomus fasciculatum . Synergistic effect of VAM and pathogen to increase on productivity vis-a-vis resistance was also studied in respect of polyphenol oxidase. The experimental findings indicated the potential use of G. fasciculatum for improving the growth and imparting resistance of brinjal and tomato.

Quantitative trait loci analysis of phytate and phosphate concentrations in seeds and leaves of Brassica rapa

Phytate, being the major storage form of phosphorus in plants, is considered to be an anti-nutritional substance for human, because of its ability to complex essential micronutrients. In the present study, we describe the genetic analysis of phytate and phosphate concentrations in Brassica rapa using five segregating populations, involving eight parental accessions representing different cultivar groups. A total of 25 quantitative trait loci (QTL) affecting phytate and phosphate concentrations in seeds and leaves were detected, most of them located in linkage groups R01, R03, R06 and R07. Two QTL affecting seed phytate (SPHY), two QTL affecting seed phosphate (SPHO), one QTL affecting leaf phosphate and one major QTL affecting leaf phytate (LPHY) were detected in at least two populations. Co-localization of QTL suggested single or linked loci to be involved in the accumulation of phytate or phosphate in seeds or leaves. Some co-localizing QTL for SPHY and SPHO had parental alleles with effects in the same direction suggesting that they control the total phosphorus concentration. For other QTL, the allelic effect was opposite for phosphate and phytate, suggesting that these QTL are specific for the phytate pathway.

Scavenger activity of Allium psekemense B. Fedtsch.

In the present study the antioxidative properties of the bulbs, leaves and stalks of Allium psekemense B. Fedtsch were investigated. The activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and also the content of total flavonoids, chlorophylls a and b, carotenoids, vitamin C and soluble proteins were determined. The results indicate that extracts from all plant organs exhibited antioxidant activity. The highest antioxidant activity was observed in the leaves. Furthermore, the ESR signal of DMPO-OH radical adducts in the presence of the leaf phosphate buffer (pH 7) extract was reduced by 54.3%.

Effect of mycorrhizal‐enhanced leaf phosphate status on carbon partitioning, translocation and photosynthesis in cucumber

ABSTRACTAn assessment of the effects of arbuscular mycorrhizal (AM) infection on photosynthesis, carbon (C) allocation, translocation and biomass production of cucumber, grown in sand culture, was made using a previously determined phosphorus (P) supply (0·13 mol m−3 P) which had a significant impact on AM infection. Separation of a direct effect of AM infection from an indirect one due to an enhanced leaf P status was achieved using a comparable non‐mycorrhizal treatment (NAM + P) supplemented with extra P (0·19 mol m−3 P). Total leaf P concentration, specific leaf mass, photosynthetic capacity, and incorporation of 14C into non‐structural carbohydrate pools were dependent on leaf age. Both maximum and ambient photosynthetic rates were significantly higher in the youngest fully expanded leaves from AM and NAM + P plants which also had the higher leaf P concentrations. There were no differences in the total concentrations of starch, sucrose, raffinose or stachyose in young or old leaves among AM, non‐mycorrhizal (NAM) and NAM + P treatments. However, younger leaves of NAM plants showed a shift in 14C‐partitioning from stachyose and raffinose synthesis to starch accumulation. Determination of ADP‐glucose pyrophosphorylase (AGPase), sucrose synthase and sucrose phosphate synthase enzyme activities revealed that only AGPase activity was correlated with the increased incorporation rate of 14C into starch in young leaves of NAM plants. Although there were significant AM‐specific effects on C translocation to the root system, AM plants had similar rate of photosynthesis to NAM + P plants. These results suggest that the increase in photosynthetic rate in leaves of AM‐infected cucumber was due to an increased P status, rather than a consequence of a mycorrhizal ‘sink’ for assimilates.

Leaf Phosphate Status, Photosynthesis, and Carbon Partitioning in Sugar Beet (IV. Changes with Time Following Increased Supply of Phosphate to Low-Phosphate Plants).

Changes in photosynthesis, carbon partitioning, and growth following resupply of orthophosphate (Pi) to moderately P-deficient plants (low-P) were determined for sugar beets (Beta vulgaris L. cv F58-554H1) cultured hydroponically in growth chambers. One set of plants was supplied with 1.0 mM Pi in half-strength Hoagland solution (control plants), and a second set (low-P plants) was supplied with 0.05 mM Pi. At the end of 2 weeks, the low-P plants were resupplied with 1.0 mM Pi. Low-P plants rapidly accumulated large amounts of Pi, and the photosynthesis rate increased to control values within 4 to 6 h. The rate of photosynthesis appeared to be controlled by ribulose-1,5-bisphosphate (RuBP); low P reduced photosynthesis and RuBP levels, and P resupply increased photosynthesis and RuBP in a manner parallel with time. Low-P treatment reduced adenylate levels substantially but not nicotinamide nucleotides; adenylate levels recovered to control values over 3 to 6 h. With low P, more photosynthate is allocated to non-P carbon compounds (e.g. starch, sucrose) than to sugar phosphates. When P is resupplied, sugar phosphates increase as starch and sucrose pools decrease; this increase in leaf (chloroplast) sugar phosphates was most likely responsible for the increases in RuBP and photosynthesis and may have increased adenylate levels (through enhanced levels of ribose-5-phosphate).

Layer and broiler poultry manure as nitrogen fertilizer sources for cabbage production

Abstract Floor litter from one‐year‐old laying hens (LHM) and from eight‐week‐old broiler chickens (BCM) were incorporated in the soil of two fields and evaluated as nitrogen (N) sources for cabbage production on a non nutrient‐depleted soil. LHM had 3.4% moisture, 3.84% N and 3.41% phosphorus (P). BCM had 2.3% moisture, 4.46% N and 2.19% P. Field 1 recieved 2.4 t/ha BCM, 3.0 t/ha LHM, whereas Field 2 recieved 4.8 t/ha BCM and 6.1 t/ha LHM. Also, each field received ammonium sulfate [(NH4)2SO4] at a N rate of 100 kg/ha and an unfertilized control treatment. The manure was applied one week before cabbage transplanting on 18 May 1992. Ammonium sulfate was applied in two equal split applications during the growing season. Leaf nitrate‐nitrogen (NO3‐N) was higher at harvest in plants receiving the higher manure rate than in other treatments (P<0.05). Leaf phosphate (PO4‐P) was higher in early season in plants receiving LHM at both Tates than in other treatments. Soil BD, EC, NO3‐N, and P at harvest were not affected by the treatments (P>0.05). Soil pH was reduced by the LHM in comparison to other treatments (P<0.05). Yield was comparable among all treatments (P>0.05) . It may be concluded that low application rates of LHM and BCM are equally effective in supplying the N requirements of cabbage, with BCM recommended when only N is limiting, and LHM when P is limiting.

Phosphate Deficiency in Maize. IV. Changes in Amounts of Sucrose Phosphate Synthase during the Course of Phosphate Deprivation

With low-P treatment of maize, the level of sucrose phosphate synthase (SPS) protein decreased to 15% of the control, while the “Vmax” activity stayed relatively high (100–80% of the control) and the substrate limiting activity increased about 2 fold in the leaves. These results suggest that leaf phosphate status has dual effects on the amount of SPS protein and the activation state of SPS.

Growth Kinetics, Carbohydrate, and Leaf Phosphate Content of Clover (Trifolium subterraneum L.) after Transfer to a High CO2 Atmosphere or to High Light and Ambient Air

Intact air-grown (photosynthetic photon flux density, 400 microeinsteins per square meter per second) clover plants (Trifolium subterraneum L.) were transfered to high CO(2) (4000 microliters CO(2) per liter; photosynthetic photon flux density, 400 microeinsteins per square meter per second) or to high light (340 microliters CO(2) per liter; photosynthetic photon flux density, 800 microeinsteins per square meter per second) to similarly stimulate photosynthetic net CO(2) uptake. The daily increment of net CO(2) uptake declined transiently in high CO(2), but not in high light, below the values in air/standard light. After about 3 days in high CO(2), the daily increment of net CO(2) uptake increased but did not reach the high light values. Nightly CO(2) release increased immediately in high light, whereas there was a 3-day lag phase in high CO(2). During this time, starch accumulated to a high level, and leaf deterioration was observed only in high CO(2). After 12 days, starch was two- to threefold higher in high CO(2) than in high light, whereas sucrose was similar. Leaf carbohydrates were determined during the first and fourth day in high CO(2). Starch increased rapidly throughout the day. Early in the day, sucrose was low and similar in high CO(2) and ambient air (same light). Later, sucrose increased considerably in high CO(2). The findings that (a) much more photosynthetic carbon was partitioned into the leaf starch pool in high CO(2) than in high light, although net CO(2) uptake was similar, and that (b) rapid starch formation occurred in high CO(2) even when leaf sucrose was only slightly elevated suggest that low sink capacity was not the main constraint in high CO(2). It is proposed that carbon partitioning between starch (chloroplast) and sucrose (cytosol) was perturbed by high CO(2) because of the lack of photorespiration. Total phosphate pools were determined in leaves. Concentrations based on fresh weight of orthophosphate, soluble esterified phosphate, and total phosphate markedly declined during 13 days of exposure of the plants to high CO(2) but changed little in high light/ambient air. During this time, the ratio of orthophosphate to soluble esterified phosphate decreased considerably in high CO(2) and increased slightly in high light/ambient air. It appears that phosphate uptake and growth were similarly stimulated by high light, whereas the coordination was weak in high CO(2).

Mutant of Arabidopsis Deficient in Xylem Loading of Phosphate

A mutant of Arabidopsis thaliana deficient in the accumulation of inorganic phosphate has been isolated by screening directly for plants with altered quantities of total leaf phosphate. The mutant plants accumulate approximately 5% as much inorganic phosphate, and 24 to 44% as much total phosphate, as wild-type plants in aerial portions of the plant. Growth of the mutant is reduced, relative to wild type, and it exhibits other symptoms normally associated with phosphate deficiency. The phosphate deficiency is caused by a single nuclear recessive mutation at a locus designated pho1. The rate of phosphate uptake into the roots was similar between mutant and wild-type plants over a wide range of external phosphate concentrations. In contrast, when plants were grown in media containing 200 micromolar phosphate or less, phosphate transfer to the shoots of the mutant was reduced to 3 to 10% of the wild-type levels. The defect in phosphate transfer to the shoots could be overcome by providing higher levels of phosphate. Transfer of sulfate to the shoots was essentially normal in the mutant, indicating that the pho1 lesion was not a general defect in anion transport. Movement of phosphate through the xylem of the shoots was not impaired. The results suggest that the mutant is deficient in activity of a protein required to load phosphate into the xylem.

A mathematical skeleton model of photosynthetic oscillations

A simple model of photosynthetic oscillations is proposed and analysed. The model shows that interaction of ATP generation by photophosphorylation and ATP consumption in the two kinases of the reductive pentose phosphate cycle is capable of producing oscillations with observed frequency and damping. Simulation of the effect of the leaf phosphate status on the persistence of oscillations shows qualitative agreement with observations. The simplicity of the suggested model aids intuitive understanding of the modelling results and promotes elucidation of the mechanism of photosynthetic oscillations.

Phosphate Deficiency in Maize. I. Leaf Phosphate Status, Growth, Photosynthesis and Carbon Partitioning

Phosphate Deficiency in Maize. I. Leaf Phosphate Status, Growth, Photosynthesis and Carbon Partitioning