Assessment of Non-Phytate Phosphorus Requirements of Chinese Jing Tint 6 Layer Chicks from Hatch to Day 42.

We aimed to estimate the non-phytate phosphorus (NPP) requirements of Chinese Jing Tint 6 layer chicks. We randomly allocated 720 birds to five treatments with six cages of 24 birds each, feeding them a corn-soybean diet containing 0.36%, 0.41%, 0.46%, 0.51%, and 0.56% NNP. The results showed that the body weight gain (BWG), tibial length, and apparent total tract digestibility coefficients (ATTDC) of P were affected (p < 0.05) by dietary NPP level. A quadratic broken-line analysis (p < 0.05) of BWG indicated that the optimal NPP for birds aged 1-14 d was 0.411%. Similarly, 0.409% of NPP met tibial growth needs. However, 0.394% of NPP was optimal for P utilization according to the ATTDC criterion. For 15-42 d birds, 0.466% NPP, as estimated by the BWG criterion, was sufficient for optimal growth without decreasing P utilization. Using the factorial method, NPP requirements were calculated as 0.367% and 0.439%, based on the maintenance factors and BWG for 1-14 and 15-42 d birds, respectively, to maintain normal growth. Combining the non-linear model with the factorial method, this study recommends dietary NPP levels of 0.367% and 0.439% for 1-14 and 15-42 d birds, respectively, to optimize P utilization without affecting performance.

Divergent responses of phosphorus solubilizing bacteria with P-laden biochar for enhancing nutrient recovery, growth, and yield of canola (Brassica napus L.).

The growing global population has led to a heightened need for food production, and this rise in agricultural activity is closely tied to the application of phosphorus-based fertilizers, which contributes to the depletion of rock phosphate (RP) reserves. Considering the limited P reserves, different approaches were conducted previously for P removal from waste streams, while the adsorption of ions is a novel strategy with more applicability. In this study, a comprehensive method was employed to recover phosphorus from wastewater by utilizing biochar engineered with minerals such as calcium, magnesium, and iron. Elemental analysis of the wastewater following a batch experiment indicated the efficiency of the engineered biochar as an adsorbent. Subsequently, the phosphorus-enriched biochar, hereinafter (PL-BCsb), obtained from the wastewater, underwent further analysis through FTIR, XRD, and nutritional assessments. The results revealed that the PL-BCsb contained four times higher (1.82%) P contents which further reused as a fertilizer supplementation for Brassica napus L growth. PL-BCsb showed citric acid (34.03%), Olsen solution (10.99%), and water soluble (1.74%) P desorption. Additionally, phosphorous solubilizing bacteria (PSB) were incorporated with PL-BCsb along two P fertilizer levels P45 (45 kg ha-1) and P90 (90 kg ha-1) for evaluation of phosphorus reuse efficiency. Integrated application of PL-BCsb with half of the suggested amount of P45 (45 kg ha-1) and PSB increased growth, production, physiological, biochemical, and nutritional qualities of canola by almost two folds when compared to control. Similarly, it also improved soil microbial biomass carbon up to four times, alkaline and acid phosphatases activities both by one and half times respectively as compared to control P (0). Furthermore, this investigation demonstrated that waste-to-fertilizer technology enhanced the phosphorus fertilizer use efficiency by 55-60% while reducing phosphorus losses into water streams by 90%. These results have significant implications for reducing eutrophication, making it a promising approach for mitigating environmental pollution and addressing climate change.

The Impact of Various Organic Phosphorus Carriers on the Uptake and Use Efficiency in Barley.

Organic phosphorus (OP) is an essential component of the soil P cycle, which contributes to barley nutrition after its mineralization into inorganic phosphorus (Pi). However, the dynamics of OP utilization in the barley rhizosphere remain unclear. In this study, phytin was screened out from six OP carriers, which could reflect the difference in OP utilization between a P-inefficient genotype Baudin and a P-efficient genotype CN4027. The phosphorus utilization efficiency (PUE), root morphological traits, and expression of genes associated with P utilization were assessed under P deficiency or phytin treatments. P deficiency resulted in a greater root surface area and thicker roots. In barley fed with phytin as a P carrier, the APase activities of CN4027 were 2-3-fold lower than those of Baudin, while the phytase activities of CN4027 were 2-3-fold higher than those of Baudin. The PUE in CN4027 was mainly enhanced by activating phytase to improve the root absorption and utilization of Pi resulting from OP mineralization, while the PUE in Baudin was mainly enhanced by activating APase to improve the shoot reuse capacity. A phosphate transporter gene HvPHT1;8 regulated P transport from the roots to the shoots, while a purple acid phosphatase (PAP) family gene HvPAPhy_b contributed to the reuse of P in barley.

Arbuscular Mycorrhizal Fungi Response on Soil Phosphorus Utilization and Enzymes Activities in Aerobic Rice under Phosphorus-Deficient Conditions.

The prominence of arbuscular mycorrhizal fungi (AMF) in sustainable rice production has long been recognized. However, there is little information about AMF response in aerobic rice cultivation under phosphorus (P)-deficient conditions. The aim of this experiment was to compare and determine the preeminent AMF effects on rice mycorrhizal colonization, responsiveness, P utilization, and different growth-promoting traits under P-deficient conditions. Different AMF genera viz. (Funneliformis sp., Rhizophagus sp., Glomus sp., Acaulospora sp., and Claroideoglomus sp.) in four different aerobic rice varieties developed by ICAR-NRRI, India (CR Dhan 201, CR Dhan 204, CR Dhan 205, and CR Dhan 207) were investigated using the check P-susceptible variety (IR 36) and the P-tolerant variety (Kasalath IC459373). Data analyzed through linear modeling approaches and bivariate associations found that AMF colonization was highly correlated with soil enzymes, particularly fluorescein diacetate (FDA) and plant P uptake. The microbial biomass carbon (MBC) and FDA content were significantly changed among rice varieties treated with AMF compared to uninoculated control. Out of four different rice varieties, CR Dhan 207 inoculated with AMF showed higher plant P uptake compared to other varieties. In all the rice varieties, AMF colonization had higher correlation coefficients with soil enzymes (FDA), MBC, and plant P uptake than uninoculated control. The present study indicates that AMF intervention in aerobic rice cultivation under P-deficient conditions significantly increased plant P uptake, soil enzymes activities and plant growth promotion. Thus, the information gathered from this study will help us to develop a viable AMF package for sustainable aerobic rice cultivation.

Comparative physiological and proteomic response to phosphate deficiency between two wheat genotypes differing in phosphorus utilization efficiency.

Genetic variation in phosphorus utilization efficiency (PUE) widely exists among wheat genotypes. However, the underlying mechanisms are still unclear. Two contrasting wheat genotypes, Heng4399 (H4399) and Tanmai98 (TM98), were screened out from 17 bread wheat genotypes based on shoot soluble phosphate (Pi) concentrations. The TM98 had a significantly higher PUE than the H4399, especially under Pi deficiency. The induction of genes in the PHR1-centered Pi signaling pathway was significantly higher in TM98 than in H4399. Collectively, through a label-free quantitative proteomic analysis, 2110 high-confidence proteins were identified in shoots of the two wheat genotypes. Among them, 244 and 133 proteins were differentially accumulated under Pi deficiency in H4399 and TM98, respectively. The abundance of proteins related to nitrogen and phosphorus metabolic processes, small molecule metabolic process, and carboxylic acid metabolic process weas significantly affected by Pi deficiency in the shoots of the two genotypes. The abundance of proteins in energy metabolism, especially photosynthesis, was decreased by Pi deficiency in the shoots of H4399. Inversely, the PUE-efficient genotype TM98 could maintain protein abundance in energy metabolism. Moreover, the proteins involved in pyruvate metabolism, glutathione metabolism, and sulfolipid biosynthesis were significantly accumulated in TM98, which probably contributed to its high PUE. SIGNIFICANCE: Improving the PUE of wheat is urgent and crucial for sustainable agriculture. Genetic variation among wheat genotypes provides materials for exploring the underlying mechanisms for high PUE. This study selected two wheat genotypes with contrasting PUE to reveal the differences in the physiological and proteomic responses to phosphate deficiency. The PUE-efficiency genotype TM98 greatly induced the expression of genes in the PHR1-centered Pi signaling pathway. Subsequently, the TM98 could maintain the abundance of proteins related to energy metabolism and enhance the abundance of proteins involved in pyruvate metabolism, glutathione metabolism, and sulfolipid biosynthesis to increase PUE under Pi deficiency. The differentially expressed genes or proteins between the genotypes with contrasting PUE would provide potential and basis for breeding wheat varieties with improved phosphorus use efficiency.

Biochemical and Molecular Responses Underlying the Contrasting Phosphorus Use Efficiency in Ryegrass Cultivars.

Improving plant ability to acquire and efficiently utilize phosphorus (P) is a promising approach for developing sustainable pasture production. This study aimed to identify ryegrass cultivars with contrasting P use efficiency, and to assess their associated biochemical and molecular responses. Nine ryegrass cultivars were hydroponically grown under optimal (0.1 mM) or P-deficient (0.01 mM) conditions, and P uptake, dry biomass, phosphorus acquisition efficiency (PAE) and phosphorus utilization efficiency (PUE) were evaluated. Accordingly, two cultivars with high PAE but low PUE (Ansa and Stellar), and two cultivars with low PAE and high PUE (24Seven and Extreme) were selected to analyze the activity and gene expression of acid phosphatases (APases), as well as the transcript levels of P transporters. Our results showed that ryegrass cultivars with high PAE were mainly influenced by root-related responses, including the expression of genes codifying for the P transporter LpPHT1;4, purple acid phosphatase LpPAP1 and APase activity. Moreover, the traits that contributed greatly to enhanced PUE were the expression of LpPHT1;1/4 and LpPHO1;2, and the APase activity in shoots. These outcomes could be useful to evaluate and develop cultivars with high P-use efficiency, thus contributing to improve the management of P in grassland systems.

Effects of Dietary Phosphorus Levels on Growth Performance, Phosphorus Utilization and Intestinal Calcium and Phosphorus Transport-Related Genes Expression of Juvenile Chinese Soft-Shelled Turtle (Pelodiscus sinensis).

A 60-day feeding trial was performed to assess the effects of dietary phosphorus levels on growth performance, body composition, phosphorus utilization, plasma physiological parameters and intestinal Ca and P transport-related gene expression of juvenile Chinese soft-shelled turtle (P. sinensis). Four diets containing available P at graded levels of 0.88%, 1.00%, 1.18% and 1.63% (termed as D0.88, D1.00, D1.18 and D1.63, respectively) were formulated and each diet was fed to turtles (5.39 ± 0.02 g) in sextuplicate. The turtles were randomly distributed to 24 tanks with 8 turtles per tank. The results indicated that final body weight, specific growth rate, feed conversion ratio and protein efficiency ratio performed best in turtles fed 1.00% available P diet. The crude lipids of the whole body exhibited a decreasing trend with the dietary available P, whereas the calcium and phosphorus of the whole body and bone phosphorus showed an opposite tendency. The apparent digestibility coefficient of phosphorus declined with the dietary available P. Turtles fed 1.00% available phosphorus had the highest phosphorus retention ratio compared with other treatments. Simultaneously they had significantly lower phosphorus loss than turtles fed D1.18 and D1.63 and had no differences in this respect from turtles fed a low-phosphorus diet. It was noteworthy that the lowest plasma calcium concentrations, and alkaline phosphatase activities in plasma and liver, were discovered in turtles fed the diet containing 1.63% available phosphorus. In addition, the high-phosphorus diet resulted in significantly down-regulated expression of intestinal phosphorus and calcium transport-related key genes. In conclusion, the available phosphorus requirement of juvenile P. sinensis was determined at 1.041% (total phosphorus was 1.80%) based on quadratic regression of weight gain rate, and excessive dietary phosphorus stunted turtle growth possibly via inhibiting intestinal calcium absorption.

Monogalactosyl diacylglycerol synthase 3 affects phosphate utilization and acquisition in rice.

Galactolipids are essential to compensate for the loss of phospholipids by 'membrane lipid remodelling' in plants under phosphorus (P) deficiency conditions. Monogalactosyl diacylglycerol (MGDG) synthases catalyse the synthesis of MGDG which is further converted into digalactosyl diacylglycerol (DGDG), later replacing phospholipids in the extraplastidial membranes. However, the roles of these enzymes are not well explored in rice. In this study, the rice MGDG synthase 3 gene (OsMGD3) was identified and functionally characterized. We showed that the plant phosphate (Pi) status and the transcription factor PHOSPHATE STARVATION RESPONSE 2 (OsPHR2) are involved in the transcriptional regulation of OsMGD3. CRISPR/Cas9 knockout and overexpression lines of OsMGD3 were generated to explore its potential role in rice adaptation to Pi deficiency. Compared with the wild type, OsMGD3 knockout lines displayed a reduced Pi acquisition and utilization while overexpression lines showed an enhancement of the same. Further, OsMGD3 showed a predominant role in roots, altering lateral root growth. Our comprehensive lipidomic analysis revealed a role of OsMGD3 in membrane lipid remodelling, in addition to a role in regulating diacylglycerol and phosphatidic acid contents that affected the expression of Pi transporters. Our study highlights the role of OsMGD3 in affecting both internal P utilization and P acquisition in rice.

Functional differentiation and complementation of alkaline phosphatases and choreography of DOP scavenging in a marine diatom.

Facing phosphate deficiency, phytoplankton use alkaline phosphatase (AP) to scavenge dissolved organophosphate (DOP). AP is a multitype (e.g., PhoA, PhoD) family of hydrolases and is known as a promiscuous enzyme with broad DOP substrate compatibility. Yet, whether the multiple types differentiate on substrates and collaborate to provide physiological flexibility remain elusive. Here we identify PhoA and PhoDs and document the functional differentiation between PhoA and a PhoD (PhoD_45757) in Phaeodactylum tricornutum. CRISPR/Cas9-based mutations and physiological analyses reveal that (1) PhoA is a secreted enzyme and contributes the majority of total AP activity whereas PhoD_45757 is intracellular and contributes a minor fraction of the total AP activity, (2) AP gene expression compensates for each other after one is disrupted, (3) the DOP→PhoA→phosphate_uptake and the DOP_uptake→PhoD→phosphate pathways function interchangeably for some DOP substrates. These findings shed light on the underpinning of AP's multiformity and have important implications in phytoplankton phosphorus-nutrient niche differentiation, physiological plasticity, and competitive strategy.

The Effects of Inorganic Phosphorus Levels on Phosphorus Utilization, Local Bone-Derived Regulators, and BMP/MAPK Pathway in Primary Cultured Osteoblasts of Broiler Chicks.

Understanding the underlying mechanisms that regulate the bone phosphorus (P) utilization would be helpful for developing feasible strategies to improve utilization efficiency of P in poultry. We aimed to investigate the effects of inorganic P levels on P utilization, local bone-derived regulators and bone morphogenetic protein/mitogen-activated protein kinase (BMP/MAPK) pathway in primary cultured osteoblasts of broiler chicks in order to address whether local bone-derived regulators or BMP/MAPK pathway was involved in regulating the bone P utilization of broilers using an in vitro model. The primary cultured tibial osteoblasts of broiler chicks were randomly divided into one of five treatments with six replicates for each treatment. Then, cells were respectively incubated with 0.0, 0.5, 1.0, 1.5, or 2.0 mmol/L of added P as NaH2PO4 for 24 days. The results showed that as added P levels increased, tibial osteoblastic P retention rate, number and area of mineralized nodules, the mRNA expressions of endopeptidases on the X chromosome (PHEX), dentin matrix protein 1 (DMP1), bone morphogenetic protein 2 (BMP2), and the mRNA and protein expressions of matrix extracellular phosphoglycoprotein (MEPE) increased linearly (p < 0.001) or quadratically (p < 0.04), while extracellular signal-regulated kinase 1 (ERK1) mRNA expression and c-Jun N-terminal kinase 1 (JNK1) phosphorylated level decreased linearly (p < 0.02) or quadratically (p < 0.01). Correlation analyses showed that tibial osteoblastic P retention rate was positively correlated (r = 0.452-0.564, p < 0.03) with MEPE and BMP2 mRNA expressions. Furthermore, both number and area of mineralized nodules were positively correlated (r = 0.414-0.612, p < 0.03) with PHEX, DMP1, MEPE, and BMP2 mRNA expressions but negatively correlated (r = -0.566 to -0.414, p < 0.04) with the ERK1 mRNA expression and JNK1 phosphorylated level. These results suggested that P utilization in primary cultured tibial osteoblasts of broiler chicks might be partly regulated by PHEX, DMP1, MEPE, BMP2, ERK1, and JNK1.

Combining analyses of metabolite profiles and phosphorus fractions to explore high phosphorus utilization efficiency in maize.

Phosphorus (P) limitation is a significant factor restricting crop production in agricultural systems, and enhancing the internal P utilization efficiency (PUE) of crops plays an important role in ensuring sustainable P use in agriculture. To better understand how P is remobilized to affect crop growth, we first screened P-efficient (B73 and GEMS50) and P-inefficient (Liao5114) maize genotypes at the same shoot P content, and then analyzed P pools and performed non-targeted metabolomic analyses to explore changes in cellular P fractions and metabolites in maize genotypes with contrasting PUE. We show that lipid P and nucleic acid P concentrations were significantly lower in lower leaves of P-efficient genotypes, and these P pools were remobilized to a major extent in P-efficient genotypes. Broad metabolic alterations were evident in leaves of P-efficient maize genotypes, particularly affecting products of phospholipid turnover and phosphorylated compounds, and the shikimate biosynthesis pathway. Taken together, our results suggest that P-efficient genotypes have a high capacity to remobilize lipid P and nucleic acid P and promote the shikimate pathway towards efficient P utilization in maize.

Mechanisms for improving phosphorus utilization efficiency in plants.

BACKGROUND: Limitation of plant productivity by phosphorus (P) supply is widespread and will probably increase in the future. Relatively large amounts of P fertilizer are applied to sustain crop growth and development and to achieve high yields. However, with increasing P application, plant P efficiency generally declines, which results in greater losses of P to the environment with detrimental consequences for ecosystems. SCOPE: A strategy for reducing P input and environmental losses while maintaining or increasing plant performance is the development of crops that take up P effectively from the soil (P acquisition efficiency) or promote productivity per unit of P taken up (P utilization efficiency). In this review, we describe current research on P metabolism and transport and its relevance for improving P utilization efficiency. CONCLUSIONS: Enhanced P utilization efficiency can be achieved by optimal partitioning of cellular P and distributing P effectively between tissues, allowing maximum growth and biomass of harvestable plant parts. Knowledge of the mechanisms involved could help design and breed crops with greater P utilization efficiency.

Phytate as a Phosphorus Nutrient with Impacts on Iron Stress-Related Gene Expression for Phytoplankton: Insights from the Diatom Phaeodactylum tricornutum.

Phytoplankton have evolved a capability to acquire phosphorus (P) from dissolved organic phosphorus (DOP) since the preferred form, dissolved inorganic phosphate (DIP, or Pi), is often limited in parts of the ocean. Phytic acid (PA) is abundantly synthesized in plants and rich in excreta of animals, potentially enriching the DOP pool in coastal oceans. However, whether and how PA can be used by phytoplankton are poorly understood. Here, we investigated PA utilization and underlying metabolic pathways in the diatom model Phaeodactylum tricornutum. The physiological results showed that P. tricornutum could utilize PA as a sole source of P nutrient to support growth. Meanwhile, the replacement of PA for DIP also caused changes in multiple cellular processes, such as inositol phosphate metabolism, photosynthesis, and signal transduction. These results suggest that PA is bioavailable to P. tricornutum and can directly participate in the metabolic pathways of PA-grown cells. However, our data showed that the utilization of PA was markedly less efficient than that of DIP, and PA-grown cells exhibited P and iron (Fe) nutrient stress signals. Implicated in these findings is the potential of complicated responses of phytoplankton to an ambient DOP species, which calls for more systematic investigation. IMPORTANCE PA is abundant in plants and cannot be digested by nonruminant animals. Hence, it is potentially a significant component of the DOP pool in coastal waters. Despite this potential importance, there is little information about its bioavailability to phytoplankton as a source of P nutrient and the molecular mechanisms involved. In this study, we found that part of PA could be utilized by the diatom P. tricornutum to support growth, and another portion of PA can act as a substrate directly participating in various metabolism pathways and cellular processes. However, our physiological and transcriptomic data show that PA-grown cells still exhibited signs of P stress and potential Fe stress. These results have significant implications in phytoplankton P nutrient ecology and provide a novel insight into multifaceted impacts of DOP utilization on phytoplankton nutrition and metabolism.

Effect of Glomus intraradices on root morphology, biomass production and phosphorous use efficiency of Chinese fir seedlings under low phosphorus stress.

Introduction: Available phosphorus (P) scarcity in the highly weathered soils of the subtropical forests in southern China is a serious concern. To ensure whether inoculation of arbuscular mycorrhizal fungi (AMF) with Chinese fir (Cunninghamia lanceolata) under low P stress conditions could promote its growth and P utilization capacity, an indoor pot simulation experiment was carried out with the different P supply treatments and Chinese fir seedlings as the tested material. Methods: The experiment had two P supply treatments, no P supply (P0, 0 mmol·L-1 KH2PO4) and normal P supply (P1, 1.0 mmol·L-1 KH2PO4). The seedling in each P supply treatment was inoculated with Glomus intraradices (Gi), a widespread species of AMF in the natural environment, and with no AMF inoculation as a control treatment (CK). The Gi infection rate in the root system, root cortex tissue dissolution rate, root morphological indexes and biomass, whole plant P use efficiency, and root P use efficiency of Chinese fir were determined under different treatment conditions. Results and Discussion: The results showed that P0 treatment significantly increased the Gi infection rate (p< 0.05). After inoculating AMF with different P supply treatments, the root cortex tissue dissolution rate was considerably enhanced. In contrast, the Chinese fir's root length and surface area were reduced; however, the root volume did not change significantly. The average root diameter in the P0 treatment and inoculated with AMF was significantly more prominent than in the uninoculated treatment (p< 0.05). The root biomass and root-to-shoot ratio at different P supply treatments were significantly higher in the Gi infection treatment than in the CK group. Under different P supply treatments, root inoculation with Gi promoted root P use efficiency and whole plant P use efficiency. In conclusion, low P stress condition promoted the colonization of AMF in the root system, increased the dissolution of root cortex tissue, root volume, and the average diameter, and promoted root biomass accumulation and P use efficiency.

Genetic Variation for Traits Related to Phosphorus Use Efficiency in Lens Species at the Seedling Stage.

Phosphorus (P) is an essential, non-renewable resource critical for crop productivity across the world. P is immobile in nature and, therefore, the identification of novel genotypes with efficient P uptake and utilization under a low P environment is extremely important. This study was designed to characterize eighty genotypes of different Lens species for shoot and root traits at two contrasting levels of P. A significant reduction in primary root length (PRL), total surface area (TSA), total root tips (TRT), root forks (RF), total dry weight (TDW), root dry weight (RDW) and shoot dry weight (SDW) in response to P deficiency was recorded. A principal component analysis revealed that the TDW, SDW and RDW were significantly correlated to P uptake and utilization efficiency in lentils. Based on total dry weight (TDW) under low P, L4727, EC718309, EC714238, PL-97, EC718348, DPL15, PL06 and EC718332 were found promising. The characterization of different Lens species revealed species-specific variations for the studied traits. Cultivated lentils exhibited higher P uptake and utilization efficiency as compared to the wild forms. The study, based on four different techniques, identified EC714238 as the most P use-efficient genotype. The genotypes identified in this study can be utilized for developing mapping populations and deciphering the genetics for breeding lentil varieties suited for low P environments.

Comparison of different selection traits for identification of phosphorus use efficient lines in mungbean.

Phosphorus (P) is one of the major constraints for crop growth and development, owing to low availability and least mobility in many tropical soil conditions. Categorization of existing germplasm under P deficient conditions is a prerequisite for the selection and development of P efficient genotypes in the mungbean. In the present investigation, 36 diverse genotypes were categorized for phosphorus use efficiency traits using four different techniques for identification of phosphorus use efficient mungbean genotypes. The studied genotypes were categorized for P efficiency based on efficiency, responsiveness, and stress tolerance score of genotypes under normal and low P conditions. The mean values of traits, root dry mass, root to shoot ratio, and P utilization efficiency are significantly higher under low P conditions indicating the high responsiveness of traits to P deficiency. The presence of significant interaction between genotypes and P treatment indicates the evaluated genotypes were significantly affected by P treatment for studied traits. The total P uptake showed significant and positive correlations with root dry mass, shoot dry mass, total dry mass,and P concentration under both P regimes. Out of the four techniques used for the categorization of genotypes for P efficiency, three techniques revealed that the genotype PUSA 1333, followed by Pusa Vishal, PUSA 1031, and Pusa Ratna is efficient. The categorization based on stress tolerance score is the finest way to study variation and for the selection of contrasting genotypes for P efficiency. The identified P efficient genotypes would be valuable resources for genetic enhancement of P use efficiency in mungbean breeding.

Effects of long-term phosphorus application on crop yield, phosphorus absorption, and soil phosphorus accumulation in maize-wheat rotation system.

In this study, we examined the effects of four phosphorus treatments on crop yields, and analyzed crop phosphorus uptake and phosphorus utilization efficiency, as well as changes in soil phosphorus deficit in maize-wheat rotation system, based on a 7-year field experiment in Baoding City, Hebei Province. The results showed that long-term phosphorus application significantly increased the yield and phosphorus uptake of maize and wheat. The yield and phosphorus uptake of maize and wheat showed a parabolic trend that first increased and then decreased with the increases of phosphorus application. The utilization efficiency of phosphorus fertilizer in the corn season was higher than that in the wheat season under various phosphorus application treatments. The cumulative utilization efficiency of phosphorus fertilizer in the wheat season showed a downward trend. The decline rate showed that optimized phosphorus application > 70% optimized phosphorus application >130% optimized phosphorus application. The cumulative utilization efficiency of phosphorus fertili-zer in the corn season showed an upward trend. For the rising rate, the optimized phosphorus application > 70% optimized phosphorus application > 130% optimized phosphorus application. Both the apparent phosphorus surplus and the accumulated phosphorus surplus of the soil without phosphorus application were under phosphorus deficiency. Under the treatment of phosphorus application, soil phosphorus showed a status of phosphorus surplus. The higher the phosphorus application rate, the longer the accumulation period, the higher the soil phosphorus surplus. Under the straw returning condition, phosphorus application rate for wheat of 105-150 kg·hm-2 and the phosphorus application rate for maize of 63-90 kg·hm-2 in Hebei fluvo-aquic soil could ensure the high crop yield, keep the phosphorus utilization efficiency at a high level, and reduce soil phosphorus accumulation and environmental risks.

Holstein dairy cows with high phosphorus utilization efficiency fed a low phosphorous diet secreted less phosphorus with urine but more with milk and feces.

The environmental pollution of phosphorus (P) from livestock farming is becoming increasingly problematic especially with regard to dwindling global P resources. Thus, a more sustainable handling of P resources, including improvements in P use efficiency and a reduction of P loss from farm animals, is necessary. Dairy cows may differ in milk P yield and P use efficiency despite receiving the same feed ration. The objective of this study was to elucidate inter-individual differences in P and closely linked nitrogen (N) excretions and the expression of P transport proteins in dairy cows with low and high P utilization efficiency. Twenty multiparous, late lactating German Holstein dairy cows were retrospectively assigned to either a high (HPeff; n = 10) or low (LPeff; n = 10) P utilization efficiency group. Cows were fed a diet low in P and crude protein (CP) content. During a 4-day balance study, feed intake, urine and fecal excretions, and milk yield were recorded to determine total P and N content in subsamples. Mammary gland, kidney and jejunal mucosa were sampled to analyze mRNA expressions of P transporters by real-time-PCR. A high milk P yield in HPeff cows strongly correlated with milk protein and milk N yield. HPeff cows excreted less urinary P, had a higher renal P reabsorption rate, and a higher renal sodium-P cotransporter 2 expression than LPeff cows. As HPeff cows channeled more P into milk, they mobilized more P from body reserves as indicated by their more negative P-balance. In addition, HPeff cows had higher fecal P excretion relative to ingested P, resulting in a lower apparent P digestibility. In conclusion, when fed a low P diet, HPeff cows channeled more endogenous P into milk and feces, which in the long-term, likely has adverse effects on animal health and the environment.

Insights into the Mitochondrial and Nuclear Genome Diversity of Two High Yielding Strains of Laying Hens.

Mitochondria are essential components of eukaryotes as they are involved in several organismic key processes such as energy production, apoptosis and cell growth. Despite their importance for the metabolism and physiology of all eukaryotic organisms, the impact of mitochondrial haplotype variation has only been studied for very few species. In this study we sequenced the mitochondrial genome of 180 individuals from two different strains of laying hens. The resulting haplotypes were combined with performance data such as body weight, feed intake and phosphorus utilization to assess their influence on the hens in five different life stages. After detecting a surprisingly low level of genetic diversity, we investigated the nuclear genetic background to estimate whether the low mitochondrial diversity is representative for the whole genetic background of the strains. Our results highlight the need for more in-depth investigation of the genetic compositions and mito-nuclear interaction in individuals to elucidate the basis of phenotypic performance differences. In addition, we raise the question of how the lack of mitochondrial variation developed, since the mitochondrial genome represents genetic information usually not considered in breeding approaches.

Novel QTL Conferring Phosphorus Acquisition and Utilization Efficiencies in Barley.

Phosphorus (P) deficiency in agricultural soil is a major constraint for crop production and increasing P acquisition efficiency (PAE) of plants is considered as one of the most cost-effective solutions for yield increase. The objective of this study was to detect quantitative trait loci (QTL) controlling (PAE) and P utilization efficiency (PUE) in barley under applied (+P) and non-applied P (-P) conditions. Based on the analysis of a recombinant inbred lines (RILs) population derived from a cross between a malting barley variety and a wild barley accession, 17 QTL controlling PAE, PUE and yield traits were detected. The phenotypic variation explained by each of these QTL ranges from 11.0 to 24.7%. Significant correlation was detected between most of P-related traits and yield traits. Five QTL clusters were identified on four different chromosomes (1H, 3H, 5H, and 7H). Two of the QTL clusters, located on chromosome 1H (for GPUP/PUP) and 7H (for SPUE/SPC), respectively, are novel. Fourteen genes located in the interval harboring the major QTL were identified as candidates associated with P efficiency. The stable QTL for PAE, PUE and yield-related traits could be important for breeding P-efficient barley varieties.