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Phosphorus (P) is a limiting nutrient in many agroecosystems and, apart from affecting plant growth, can also limit biological N2 fixation (BNF) by leguminous plants. Thus, increasing P supply can have a positive effect on BNF particularly in P-deficient soils. Here, we provide new insights into the response of hairy vetch (Vicia villosa), widely adopted as a legume cover crop, to P limitations, by comparing the effects of inorganic (Pi) and organic (Po) P supply on plant growth and BNF capacity. This was achieved by means of a greenhouse experiment in which rhizobia-inoculated hairy vetch was grown in a P-limited agricultural soil and changes in plant growth, nitrogen (N) and P uptake, BNF capacity, and soil phosphatases activities were evaluated as a function of Pi and Po inputs, in the form of orthophosphate or phytic acid, respectively. When compared to P-deficient conditions where BNF was primarily limited by plant growth rather than directly due to the high P costs of symbiotic N fixation, Pi addition substantially enhanced plant growth (threefold), nodule formation (16-fold), P acquisition (sixfold), and BNF efficiency (sevenfold). In contrast, even with the addition of the highest dose of Po, the increase in plant growth, nodule formation, P acquisition, and BNF capacity (1.7, 3.5, 2.4 and 2.1-fold, respectively) was much less expressed, indicating that hairy vetch could only minimally access Po sources over the growth period in order to alleviate the P limitation effect on N2 fixation in under P-deficient conditions. These findings suggest that hairy vetch will not be able to provide sufficient BNF for improving soil N inputs in low-fertility cropping systems that rely on organic inputs., Universita degli Studi di Torino within the CRUI-CARE Agreement, Cassa di Risparmio di Torino

Triphyophyllum peltatum, a rare tropical African liana, is unique in its facultative carnivory. The trigger for carnivory is yet unknown, mainly because the plant is difficult to propagate and cultivate. This study aimed at identifying the conditions that result in the formation of carnivorous leaves. In vitro shoots were subjected to abiotic stressors in general and deficiencies of the major nutrients nitrogen, potassium and phosphorus in particular, to trigger carnivorous leaves' development. Adventitious root formation was improved to allow verification of the trigger in glasshouse-grown plants. Among all the stressors tested, only under phosphorus deficiency, the formation of carnivorous leaves was observed. These glandular leaves fully resembled those found under natural growing conditions including the secretion of sticky liquid by mature capture organs. To generate plants for glasshouse experiments, a pulse of 55.4 μM α-naphthaleneacetic acid was essential to achieve 90% in vitro rooting. This plant material facilitated the confirmation of phosphorus starvation to be essential and sufficient for carnivory induction, also under ex vitro conditions. Having established the cultivation of T. peltatum and the induction of carnivory, future gene expression profiles from phosphorus starvation-induced leaves will provide important insight to the molecular mechanism of carnivory on demand.

Background and Aims Initiation of cluster roots in white lupin (Lupinus albus) under phosphorus (P) deficiency requires auxin signalling, whereas flavonoids inhibit auxin transport. However, little information is available about the interactions between P deficiency and flavonoids in terms of cluster-root formation in white lupin. Methods Hydroponic and aeroponic systems were used to investigate the role of flavonoids in cluster-root formation, with or without 75 μm P supply. Key Results Phosphorus-deficiency-induced flavonoid accumulation in cluster roots depended on developmental stage, based on in situ determination of fluorescence of flavonoids and flavonoid concentration. LaCHS8, which codes for a chalcone synthase isoform, was highly expressed in cluster roots, and silencing LaCHS8 reduced flavonoid production and rootlet density. Exogenous flavonoids suppressed cluster-root formation. Tissue-specific distribution of flavonoids in roots was altered by P deficiency, suggesting that P deficiency induced flavonoid accumulation, thus fine-tuning the effect of flavonoids on cluster-root formation. Furthermore, naringenin inhibited expression of an auxin-responsive DR5:GUS marker, suggesting an interaction of flavonoids and auxin in regulating cluster-root formation. Conclusions Phosphorus deficiency triggered cluster-root formation through the regulation of flavonoid distribution, which fine-tuned an auxin response in the early stages of cluster-root development. These findings provide valuable insights into the mechanisms of cluster-root formation under P deficiency.

The essential plant nutrient phosphorus (P) is key for numerous structures and processes in crops and its deficiency can severely restrict yield and quality. As soil P availability for plant uptake is often limited, foliar P application can be an alternative means of supplying P to the plants during the growth period. This study was aimed at investigating the effect of foliar P application on photosynthetic parameters, P nutritional status, and growth of P deficient maize over time. Plants of Zea mays L. cv. Keops were grown with deficient and sufficient amounts of P in hydroponics. Foliar P treatments were applied to P deficient plants and several physiological parameters were monitored for 21 days. The variables measured were leaf gas exchange parameters, SPAD values, foliar P absorption, re-translocation rates, and plant biomass production. Foliar P application significantly increased CO2-assimilation and SPAD values and additionally enhanced biomass production in all plant components. Elemental analysis revealed increased tissue P concentrations following foliar P application compared to P deficient plants. While increased growth of P-deficient plants was steadily promoted by foliar P spraying for the entire experimental period, the positive effect on CO2 assimilation and P concentration was transient and vanished some days after the foliar treatment. P deficiency markedly impaired the efficiency of physiological processes of maize plants. As a conclusion, foliar P fertilisation improved physiological and agronomical plant parameters over time, but failed to restore plant functionality of P deficient maize plants during a prolonged experimental period.

Thinopyrum intermedium has been used as a resource for improving resistance to biotic and abiotic stresses and yield potential in common wheat. Wheat line SN304 was derived from a cross between common wheat cultivar Yannong 15 and Th. intermedium. Genomic in situ hybridization (GISH) produced no hybridization signal in SN304 using Th. intermedium genomic DNA as a probe, but fluorescence in situ hybridization (FISH) using oligonucleotides AFA-3, AFA-4, pAs1-1, pAs1-3, pAs1-4, pAs1-6, pSc119.2-1, and (GAA)10 as probes detected hybridization signals on chromosomes 2A, 7A, 2B, 3B, 6B, and 7B in SN304 that differed from Yannong 15. Results of specific markers also indicated that there were Th. intermedium chromatin introgressions on different chromosomes in SN304. In a hydroponic culture experiment, SN304 not only produced more biomass and higher stem and leaf dry weight but also accumulated more phosphorus than Yannong 15 under phosphorus-deficiency stress. Moreover, SN304 produced a lower pH and released more organic acids, especially oxalic acid, than Yannong 15, which suggests that SN304 exudates enabled more absorbance of P than Yannong 15 under comparable conditions. The results indicate that SN304 is a wheat-Th. intermedium introgression line with tolerance to phosphorus-deficiency stress.

Heterotrimeric G protein is involved in plant growth and development, while the role of rice (Oryza sativa) G protein γ subunit qPE9-1 in response to low-phosphorus (LP) conditions remains unclear. The gene expression of qPE9-1 was significantly induced in rice roots under LP conditions. Rice varieties carrying the qPE9-1 allele showed a stronger primary root response to LP than the varieties carrying the qpe9-1 allele (mutant of the qPE9-1 allele). Transgenic rice plants with the qPE9-1 allele had longer primary roots and higher P concentrations than those with the qpe9-1 allele under LP conditions. The plasma membrane (PM) H+ -ATPase was important for the qPE9-1-mediated response to LP. Furthermore, OsGF14b, a 14-3-3 protein that acts as a key component in activating PM H+ -ATPase for root elongation, is also involved in the qPE9-1 mediation. Moreover, the overexpression of OsGF14b in WYJ8 (carrying the qpe9-1 allele) partially increased primary root length under LP conditions. Experiments using R18 peptide (a 14-3-3 protein inhibitor) showed that qPE9-1 is important for primary root elongation and H+ efflux under LP conditions by involving the 14-3-3 protein. In addition, rhizosheath weight, total P content, and the rhizosheath soil Olsen-P concentration of qPE9-1 lines were higher than those of qpe9-1 lines under soil drying and LP conditions. These results suggest that the G protein γ subunit qPE9-1 in rice plants modulates root elongation for phosphorus uptake by involving the 14-3-3 protein OsGF14b and PM H+ -ATPase, which is required for rice P use.

Rising atmospheric CO2 levels associated with climate change increase plant nutrient demands. However, few studies have examined the interactions of atmospheric CO2 and P supply on root exudation which plays a crucial role in mobilising non-labile P in soil. This study aimed to examine the interactive effects of elevated CO2 and P deficiency on root exudation of organic acid anions and sugars over time. White lupin (Lupinus albus L.) was grown at 1, 5 and 50 µM P in solution culture under ambient (380 ppm) and elevated (700 ppm) CO2 levels. Root exudates were collected after 3, 4, 5 and 6 weeks of treatment, and organic acid anions and sugars were quantified using liquid chromatography-mass spectrometry. Elevated CO2 and P deficiency positively interacted to enhance citrate exudation between 3 and 5 weeks of growth, while malate was only sporadically affected by elevated CO2 and fumarate remained unaffected. Elevated CO2 also increased exudation of glucose and fructose with larger increases being observed in P-deficient plants, which was largely constrained after 4 weeks. Elevated CO2 had no effect on exudation rates as plants matured. The positive interaction between CO2 and P deficiency led to increases in organic acid anion and sugar exudation, indicating that rising atmospheric CO2 levels could allow plants to access greater amounts of non-labile P when faced with P deficiency thereby reducing their reliance on non-renewable fertiliser inputs.

Low-molecular-weight organic acid (OA) extrusion by plant roots is critical for plant nutrition, tolerance to cations toxicity, and plant-microbe interactions. Therefore, methodologies for the rapid and precise quantification of OAs are necessary to be incorporated in the analysis of roots and their exudates. The spatial location of root exudates is also important to understand the molecular mechanisms directing OA production and release into the rhizosphere. Here, we report the development of two complementary methodologies for OA determination, which were employed to evaluate the effect of inorganic ortho-phosphate (Pi) deficiency and aluminum toxicity on OA excretion by Arabidopsis roots. OA exudation by roots is considered a core response to different types of abiotic stress and for the interaction of roots with soil microbes, and for decades has been a target trait to produce plant varieties with increased capacities of Pi uptake and Al tolerance. Using targeted ultra-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC-HRMS/MS), we achieved the quantification of six OAs in root exudates at sub-micromolar detection limits with an analysis time of less than 5 min per sample. We also employed targeted (MS/MS) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) to detect the spatial location of citric and malic acid with high specificity in roots and exudates. Using these methods, we studied OA exudation in response to Al toxicity and Pi deficiency in Arabidopsis seedlings overexpressing genes involved in OA excretion. Finally, we show the transferability of the MALDI-MSI method by analyzing OA excretion in Marchantia polymorpha gemmalings subjected to Pi deficiency.

Background: Under the background of drought and nitrogen deposition, global climate change is changing the supply of resources and environmental conditions that are crucial to plant growth, and plants respond to climate change by environmentally induced phenotypic changes. Aims: The objective of this study was to assess the differences in the plasticity responses of the morphological, photosynthetic, fluorescence and antioxidant parameters of Robinia pseudoacacia seedlings under water, nitrogen and phosphorus interaction conditions. Methods: We analyzed the above parameters of R. pseudoacacia seedlings using methods of morphological measurements, gas exchanges, fluorescence emission and antioxidant assays under two water levels (75% and 55% of field capacity), four nitrogen levels (no urea; 0.2 g kg⁻¹, 0.4 g kg⁻¹, 0.8 g kg⁻¹), and two phosphorus levels (no superphosphate, 0.6 g kg⁻¹). Results: The results showed that drought stress significantly reduced the morphological parameters, actual photochemical efficiency of photosystem II (ΦPSII), superoxide dismutase (SOD) activity, peroxidase (POD) activity and catalase (CAT) activity of R. pseudoacacia seedlings, and significantly increased nonphotochemical quenching (NPQ) and the malondialdehyde (MDA) content. Excessive application of nitrogen (N) fertilizer inhibited plant growth, and phosphorus (P) deficiency significantly weakened the positive effect of the high nitrogen treatment on morphological parameters under drought stress. The high nitrogen treatment effectively weakened the inhibitory effect of drought and phosphorus deficiency on chlorophyll formation. Proper N and P fertilizers increased the SOD, POD and CAT activities and decreased the MDA content under drought stress. The mean plasticity index of POD and CAT activities in response to water, nitrogen and phosphorus was the highest, which indicated that R. pseudoacacia seedlings can adapt to changes in water and nutrients mainly by adjusting their POD and CAT activities. Conclusions: These results may explain the better survival of R. pseudoacacia under the condition of limited water and nutrient resources, which is helpful for understanding the response mechanism of R. pseudoacacia to changes in environmental factors in the future. The results also provide scientific data and a theoretical basis for vegetation restoration and sustainable development of the regional ecological environment.

Arbuscular mycorrhizal (AM) fungal extraradical hyphae exude their metabolites into the soil. Root exudate metabolites are affected by plant species and P status. However, the effect of P status on AM hyphal exudate metabolites has been unknown. This study aimed to examine hyphal exudate metabolite composition of two AM fungal species and their response to P deficiency through metabolite profiling. Rhizophagus clarus and R. irregularis were grown in a two-compartment in vitro culture system of Linum usitatissimum roots on solid modified Strullu-Romand medium in combination with two P levels (3 µM (P3) and 30 µM (P30)). Hyphal exudates were collected from the hyphal compartment at 118 days after inoculation (DAI). The metabolite composition of the hyphal exudates was determined by capillary electrophoresis/time-of-flight mass spectrometry, resulting in the identification of a total of 141 metabolites at 118 DAI. In the hyphal exudates of R. clarus, the concentrations of 18 metabolites, including sugars, amino acids, and organic acids, were significantly higher (p

By 2050, elevated atmospheric CO2 (eCO2) could stimulate plant growth, but dwindling phosphorus (P) stocks in the soil could limit growth. However, little is known about how eCO2 could affect soil P availability and dynamics in P-poor soils. Here, we conducted a 6-week pot experiment where three plant species were grown in a low-P soil under ambient (390 ppm) and eCO2 (700 ppm) to investigate plant growth, rhizosphere properties, and changes in soil P fractions. Our results showed that under P deficiency, plant biomass, P uptake, and rhizosphere properties did not respond to eCO2. Changes were noted by plant species. Compared to the control soil (unplanted pots), rhizosphere pH decreased the most under wheat, while microbial biomass P was higher under blue lupin. Among plant species, the blue lupin rhizosphere exhibited higher acid and alkaline phosphatase activity as well as organic anion release. Soil P fractions were impacted by plant species but similar across CO2 treatments. Blue lupin accumulated labile organic P while depleted moderately labile organic P. Accumulation of labile organic P could be ascribed to microbial P immobilisation, whereas the mineralization of moderately labile organic P was associated with higher phosphatase activity. Wheat depleted acid extractable inorganic P the most, probably due to soil acidification and higher root biomass. These results suggest that plants can mobilise different P fractions irrespective of their chemical availability using morphological and/or physiological adaptations. However, these adaptations to acquire P from a low-P soil were not affected by eCO2. This implies that current P fertiliser recommendations to boost or maintain crop production in low-P soils would remain unchanged under future eCO2.

Phosphorus (P) deficiency tolerance is a pivotal trait for plant growth and development. Most of the commercial modern cultivars lack this trait and reported it as a very serious problem limiting crop productivity. This trait is advantageous if present in modern high yielding varieties as it increases the yield under the phosphorus-deficient soil conditions. With the importance of phosphorus deficiency tolerance, the present investigation was carried out with an objective to screen for tolerance to phosphorus deficiency using solution culture and phosphorus uptake 1 (Pup1) locus linked markers in 30 diverse rice genotypes. A wide range of varied responses to P deficiency in rice genotypes for all the traits were observed. Root length and enzyme activity showed increased mean performance under the − P condition when compared to + P condition. Medium to high heritability estimates were obtained for most of the traits. Correlation analysis showed that the traits: root P content, fresh shoot weight, dry shoot weight, and shoot length showed highly significant correlations with each other under − P conditions. Based on the hydroponics and molecular screening, three genotypes viz., ADT (R) 48, Improved Pusa Basmati 1 and UPLRI 5 were classified as tolerant for its response to P deficiency as they possessed significant increase in desirable root and shoot traits, increased acid phosphatase enzyme and these genotypes also possessed the Pup1 allele for all the five markers. The selected genotypes may be useful for the exploration of novel genes conferring phosphorus deficiency tolerance and used as donor parents in the breeding programs. Absence of this allele in the rice genotypes viz., drought tolerant (Anna (R) 4) and submergence tolerant (CR 1009 Sub 1) may warrant the development of multiple abiotic stress tolerance cultivars for upland and submergence cropping systems in future rice breeding program.

This experiment was conducted to investigate the effect of dietary calcium (Ca) or phosphorus (P) deficiency on bone development and related Ca or P metabolic utilization parameters of broilers from 22 to 42 days of age based on our previous study, which indicated that dietary Ca or P deficiency impaired the bone development by regulating related Ca or P metabolic utilization parameters of broilers from 1 to 21 days of age. A total of 504 one-day-old Arbor Acres male broilers were randomly assigned to 1 of 4 treatments with 7 replicates in a completely randomized design, and fed the normal control and Ca- or P-deficient diets from 1 to 21 days of age. At 22 days of age, the broilers were further fed the normal control diet (0.90% Ca+0.35% non-phytate P (NPP)), the P-deficient diet (0.90% Ca+0.18% NPP), the Ca-deficient diet (0.30% Ca+0.35% NPP) or the Ca and P-deficient diet (0.30% Ca+0.18% NPP), respectively. The results showed that dietary Ca or P deficiency decreased (P

Phosphorus is an essential nutrient during plant growth and development. It is involved in the formation of important compounds in plants, such as phospholipids, ATP, and nucleic acids. However, phosphorus is distributed unevenly in most soils, and exists primarily in the form of organophosphorus, which plants cannot use. In this study, the AtPHR1 homolog MdPHR1 was identified in apple. Our results showed that MdPHR1 contained a MYB domain and a coiled-coil domain, which were conserved in AtPHR1. The MdPHR1 transgenic lines had higher acid phosphatase activity and phosphorus content than the wild-type under phosphorus limited conditions. Overexpression of MdPHR1 enhanced tolerance to phosphorus deficiency in apple calli and Arabidopsis seedlings, and MdPHR1 could bind to the P1BS cis-element of MdPAP10 and activated its transcription. Collectively, our experimental evidence suggests that MdPHR1 may be the central regulator of the system controlling transcriptional responses to Pi starvation in apple.

Upland rice production on acid, weathered soils is often constrained by phosphorus (P) deficiency and aluminium toxicity. Farmyard manure application (FYM) can sharply enhance yields and agronomic P fertilizer (TSP) efficiency under such abiotic stresses. We tested the hypothesis that rice genotypes differ in aluminium tolerance and in the extent of using organic P, offering distinct benefits under TSP‐FYM combinations. Multiple field trials were conducted in the uplands of Madagascar, with factorial combinations of six genotypes, amendments of FYM (at a rate of 17–25 kg P ha⁻¹ vs. a zero control) and TSP application (40 kg P ha⁻¹ vs. a zero control), with blanket N&K additions. Rice grain yields reached a maximum of 6 t/ha after three years of TSP + FYM application, with an average of 3.2 t/ha over the years. Grain yields were about 1.2 t/ha for FYM only and about 1.5 t/ha for TSP only while crops failed under zero P input. Genotypic effects on rice yields were much smaller than the large effects of FYM, TSP or its combination. Application of FYM increased soil pH and CaCl₂‐extractable P while decreasing CaCl₂‐extractable aluminium. An additional liming trial indicated that the beneficial effects of FYM over TSP relate to liming effects. The FYM application lowers aluminium toxicity which overrules potential effects of organic P supply. Hence, genotypic ranking of yields and agronomic efficiency was inconsistent, without superior genotypes under FYM vs. TSP. However, Chomrong Dhan and FOFIFA 172 generally displayed superior yields. Chomrong Dhan is found to be more sensitive to aluminium toxicity whereas FOFIFA 172 is less performant under low P input. Aluminium tolerance should be considered when developing rice genotypes for high P efficiency in weathered soils. ispartof: Journal Of Agronomy And Crop Science vol:207 issue:1 pages:148-162 status: published

Phosphorus (P) is one of the essential macronutrients for rice. In this study, we used 120 rice backcross recombinant inbred lines (BRILs) derived from a cross indica cv. Changhui 891 and japonica cv. 02428. To elucidate the genetic control of P deficiency tolerance in rice, we have used high quality SNPs bin markers to identify some important loci underlying phosphorus deficiency. The bin map was generated which includes 3057 bins covering distance of 1266.5 cM with an average of 0.41 cM between markers. Based on this map, 50 loci, including four novel loci, qSL-3, qRL-11, qSDW-1, qRDW-1 with phenotypic variance 23.26%, 12.06%, 9.89% associated with P deficiency-related seedling traits were identified. No significant QTLs was found for root length under P+, shoot fresh weight P− and root length, shoot fresh weight for P+, P− and their ratio respectively. Root fresh weight, and root dry weight were strongly correlated to each other, and QTLs for these variables were located on the same chromosome 1 at the same region. Notably, 3 pleiotropic regions is the pioneer of our study, and these regions would facilitate map-based cloning to expedite the MAS selection for developing low phosphorous tolerant varieties. This study not only improves our knowledge about molecular processes associated with P deficiency, but also provides useful information to understand the genetic architecture of low phosphorous tolerance.

Background Tillering is an important agronomic trait underlying the yields and reproduction of orchardgrass (Dactylis glomerata), an important perennial forage grass. Although some genes affecting tiller initiation have been identified, the tillering regulatory network is still largely unknown, especially in perennial forage grasses. Thus, unraveling the regulatory mechanisms of tillering in orchardgrass could be helpful in developing selective strategies for high-yield perennial grasses. In this study, we generated high-throughput RNA-sequencing data from multiple tissues of tillering stage plants to identify differentially expressed genes (DEGs) between high- and low-tillering orchardgrass genotypes. Gene Ontology and pathway enrichment analyses connecting the DEGs to tillering number diversity were conducted. Results In the present study, approximately 26,282 DEGs were identified between two orchardgrass genotypes, AKZ-NRGR667 (a high-tillering genotype) and D20170203 (a low-tillering genotype), which significantly differed in tiller number. Pathway enrichment analysis indicated that DEGs related to the biosynthesis of three classes of phytohormones, i.e., strigolactones (SLs), abscisic acid (ABA), and gibberellic acid (GA), as well as nitrogen metabolism dominated such differences between the high- and low-tillering genotypes. We also confirmed that under phosphorus deficiency, the expression level of the major SL biosynthesis genes encoding DWARF27 (D27), 9-cis-beta-carotene 9′,10′-cleaving dioxygenase (CCD7), carlactone synthase (CCD8), and more axillary branching1 (MAX1) proteins in the high-tillering orchardgrass genotype increased more slowly relative to the low-tillering genotype. Conclusions Here, we used transcriptomic data to study the tillering mechanism of perennial forage grasses. We demonstrated that differential expression patterns of genes involved in SL, ABA, and GA biosynthesis may differentiate high- and low-tillering orchardgrass genotypes at the tillering stage. Furthermore, the core SL biosynthesis-associated genes in high-tillering orchardgrass were more insensitive than the low-tillering genotype to phosphorus deficiency which can lead to increases in SL biosynthesis, raising the possibility that there may be distinct SL biosynthesis way in tillering regulation in orchardgrass. Our research has revealed some candidate genes involved in the regulation of tillering in perennial grasses that is available for establishment of new breeding resources for high-yield perennial grasses and will serve as a new resource for future studies into molecular mechanism of tillering regulation in orchardgrass.

Plant growth is often limited by low soil phosphorus (P) availability, soil nitrogen (N) availability may affect plants’ responses to P supply. We studied the growth and physiological responses of alfalfa to soil P supply at different N levels. Alfalfa (Medicago sativa L.) plants were grown in an alkaline soil supplied with different levels of P (0, 5, and 20 mg kg−1) as monopotassium phosphate, and N (50 and 100 mg kg−1) as ammonium nitrate. Plant biomass and P concentrations always showed positive responses to P addition but not to N addition, nodulation was inhibited by lower P supply and higher N supply. Roots released more phosphatase and carboxylates, mainly tartrate, into the rhizosheath at lower soil P supply and higher N supply. Roots always acidified the rhizosheath, but rhizosheath pH did not vary considerably among treatments. This study demonstrates the release of tartrate as a major carboxylate as affected by soil P supply and N supply, and highlights the importance of investigating plant adaptive strategies for P acquisition from soil with different N availability for proper application of P and N fertilizers.

Inorganic phosphorus (Pi) deficiency induces anthocyanin accumulation in the leaves of some plant species; however, the molecular mechanisms underlying this phenomenon have not been well characterized. Here, we showed that microRNA399d (miR399d), high-affinity Pi transporter McPHT1;4, and McMYB10 are strongly induced in Malus leaves suffering from Pi deficiency. By culturing explants of transiently transformed plants in MS medium under conditions of Pi sufficiency and Pi deficiency, miR399d and McPHT1;4 were shown to play essential roles in the response to Pi deficiency and to play positive roles in the regulation of anthocyanin biosynthesis. Silencing of McHDA6 expression and treatment with the inhibitor trichostatin A suggested that the low expression of McHDA6 simultaneously reduced the transcription of McMET1 and decreased the methylation level of the McMYB10 promoter; however, the expression of McMYB10 and anthocyanin content were increased. Bimolecular fluorescence complementation and yeast two-hybrid assays revealed that McHDA6 binds directly to McMET1 through its BAH2 and DNMT1-RFD domains. Based on the results of our study, we propose a mechanism for the molecular regulation of anthocyanin biosynthesis, namely, the miR399d and epigenetic modification comodulation model, to explain the phenomenon in which leaves turn red under conditions of Pi deficiency.

Phosphorus (P) deficiency in soil is becoming more common, and low P efficiency restrains soybean growth and production. To explore critical factors determining efficient P use, root growth and physiological characteristics were investigated in the P-efficient soybean (Glycine max (L.) Merr.) L13 and P-inefficient soybean T3 in a sand culture experiment with two P deficient treatments (0.25 and 0.0 mM P) and a control-standard P (0.5 mM P) treatment. Results showed a decrease in soybean yield under P deficiency, but the yield reduction of genotype L13 was much less than that of T3. The grain yield of L13 was 40.5, 64.2 and 141.6% higher than that of T3, under 0.5, 0.25 and 0.0 mM P treatments, respectively. Genotype L13 activated sugar metabolism in roots and released H+ into the root hair zone to acidify the rhizosphere to resist P deficiency. P deficiency induced an increase in aspartic acid concentrations in root, the increase being substantially greater in the P efficient genotype. These findings suggested that the P-efficient genotype L13 has established more responsive mechanisms and better countermeasures against P deficiency. The findings of this study will be useful in further research aimed at optimizing soybean responses to P deficiency.

Low phosphorus (P) availability in acid soils is one of the main limiting factors in sugarcane (Saccharum officinarum L.) production. Reconstruction of the root system architecture (RSA) is a vital mechanism for crop low P adaption, while the RSA of sugarcane has not been studied in detail because of its complex root system. In this study, reconstruction of the RSA and its relationship with P acquisition were investigated in a P-efficient sugarcane genotype ROC22 (R22) and two P-inefficient genotypes Yunzhe 03-103 (YZ) and Japan 2 (JP). An efficient dynamic observation room was developed to monitor the spatiotemporal alternation of sugarcane root length density (RLD) and root distribution in soil with heterogeneous P locations. The sugarcane RSA was reconstructed under P deficiency, and R22 had an earlier response than YZ and JP and presented an obvious feature of root shallowness. Compared with the normal P condition, the shallow RLD was increased by 112% in R22 under P deficiency while decreased by 26% in YZ and not modified in JP. Meanwhile, R22 exhibited a shallower root distribution than YZ and JP under P deficiency, supported by 51 and 24% greater shallow RLD, and 96 and 67% greater shallow root weight, respectively. The ratio of shallow RLD to total RLD in R22 was 91% greater than YZ, and the ratio of shallow root weight to total root weight in R22 was greater than that of YZ and JP by 94 and 30%, respectively. As a result, R22 had a higher shoot P accumulation than YZ and JP, which thereby increased the relative leaf sheath inorganic P concentration (RLPC) by 47 and 56%, relative shoot biomass (RSB) by 36 and 33%, and relative cane weight (RCW) by 31 and 36%, compared with YZ and JP under P deficiency, respectively. We verified the reliability and efficiency of a dynamic observation room and demonstrated that a shallower root distribution contributed to improving topsoil foraging, P acquisition, and low P adaption under P deficiency in sugarcane. Therefore, a shallower root distribution merits consideration as an evaluation trait for breeding P efficient sugarcane genotypes and genetic improvement.

As the awareness on the ecological impact of chemical phosphate fertilizers grows, research turns to sustainable alternatives such as the implementation of phosphate solubilizing bacteria (PSB), which make largely immobile phosphorous reserves in soils available for uptake by plants. In this review, we introduce the mechanisms by which plants facilitate P-uptake and illustrate how PSB improve the bioavailability of this nutrient. Next, the effectiveness of PSB on increasing plant biomass and P-uptake is assessed using a meta-analysis approach. Our review demonstrates that improved P-uptake does not always translate in improved plant height and biomass. We show that the effect of PSB on plants does not provide an added benefit when using bacterial consortia compared to single strains. Moreover, the commonly reported species for P-solubilization, Bacillus spp. and Pseudomonas spp., are outperformed by the scarcely implemented Burkholderia spp. Despite the similar responses to PSB in monocots and eudicots, species responsiveness to PSB varies within both clades. Remarkably, the meta-analysis challenges the common belief that PSB are less effective under field conditions compared to greenhouse conditions. This review provides innovative insights and identifies key questions for future research on PSB to promote their implementation in agriculture.

Cotton is critical for phosphorus demands and very sensitive for its deficiency. However, identifying the effect of low-phosphorus tolerance on cotton growth, yield, and fiber quality by reducing p...

Summary Root hair development is crucial for phosphate absorption, but how phosphorus deficiency affects root hair initiation and elongation remains unclear.We demonstrated the roles of auxin efflux carrier PIN‐FORMED2 (PIN2) and phospholipase D (PLD)‐derived phosphatidic acid (PA), a key signaling molecule, in promoting root hair development in Arabidopsis thaliana under a low phosphate (LP) condition.Root hair elongation under LP conditions was greatly suppressed in pin2 mutant or under treatment with a PLDζ2‐specific inhibitor, revealing that PIN2 and polar auxin transport and PLDζ2‐PA are crucial in LP responses. PIN2 was accumulated and degraded in the vacuole under a normal phosphate (NP) condition, whereas its vacuolar accumulation was suppressed under the LP or NP plus PA conditions. Vacuolar accumulation of PIN2 was increased in pldζ2 mutants under LP conditions. Increased or decreased PIN2 vacuolar accumulation is not observed in sorting nexin1 (snx1) mutant, indicating that vacuolar accumulation of PIN2 is mediated by SNX1 and the relevant trafficking process. PA binds to SNX1 and promotes its accumulation at the plasma membrane, especially under LP conditions, and hence promotes root hair development by suppressing the vacuolar degradation of PIN2.We uncovered a link between PLD‐derived PA and SNX1‐dependent vacuolar degradation of PIN2 in regulating root hair development under phosphorus deficiency.

The soil bioavailability of phosphorus (P) is often low because of its poor solubility, strong sorption and slow diffusion in most soils; however, stress due to excess soil P can occur in greenhouse production systems subjected to high levels of P fertilizer. Silicon (Si) is a beneficial element that can alleviate multiple biotic and abiotic stresses. Although numerous studies have investigated the effects of Si on P nutrition, a comprehensive review has not been published. Accordingly, here we review: (1) the Si uptake, transport and accumulation in various plant species; (2) the roles of phosphate transporters in P acquisition, mobilization, re-utilization and homeostasis; (3) the beneficial role of Si in improving P nutrition under P deficiency; and (4) the regulatory function of Si in decreasing P uptake under excess P. The results of the reviewed studies suggest the important role of Si in mediating P imbalance in plants. We also present a schematic model to explain underlying mechanisms responsible for the beneficial impact of Si on plant adaption to P-imbalance stress. Finally, we highlight the importance of future investigations aimed at revealing the role of Si in regulating P imbalance in plants, both at deeper molecular and broader field levels.

Phosphorus (P) is an essential macronutrient needed for plant growth, development, and production. A deficiency of P causes a severe impact on plant development and productivity. Several P-based fertilizers are being used in agriculture but limited uptake of P by the plant is still a challenge to be solved. Titanium (Ti) application increases the nutrient uptake by affecting the root growth; however, the role of Ti in plant biology, specifically its application under low light and phosphorus stress, has never been reported. Therefore, a pot study was planned with foliar application of Ti (in a different concentration ranging from 0 to 1,000 mg L–1) under different light and P concentrations. The result indicated that under shade and low P conditions the foliar application of Ti in different concentrations significantly improves the plant growth parameters such as root length, root surface area, root dry matter, and shoot dry matters. The increase was observed to be more than 100% in shade and low P stressed soybean root parameter with 500 mg L–1 of Ti treatment. Ti was observed to improve the plant growth both in high P and low P exposed plants, but the improvement was more obvious in Low P exposed plants. Auxin concentration in stressed and healthy plant roots was observed to be slightly increased with Ti application. Ti application was also observed to decrease rhizosphere soil pH and boosted the antioxidant enzymatic activities with an enhancement in photosynthetic efficiency of soybean plants under shade and P stress. With 500 mg L–1 of Ti treatment, the photosynthetic rate was observed to improve by 45% under shade and P stressed soybean plants. Thus, this work for the first time indicates a good potential of Ti application in the low light and P deficient agricultural fields for the purpose to improve plant growth and development parameters.

Background Phosphorus is one of the essential elements for plant growth and development, but available phosphorus (Pi) content in many soil types is low. As a fast-growing tree species for timber production, Chinese fir is in great demand of Pi, and the lack of Pi in soil restricts the increase of productivity of Chinese fir plantation. Root morphology and the synthesis and secretion of organic acids play an important role in the uptake of phosphorus, but the molecular mechanisms of Chinese fir root responses to Pi deficiency are largely unexplored. In this study, seedlings of Yang 061 clone were grown under three Pi supply levels (0, 5 and 10 mg·L-1 P) and morphological attributes, organic acid content and enzyme activity were measured. The transcriptome data of Chinese fir root system were obtained and the expression levels of phosphorus responsive genes and organic acid synthesis related genes on citric acid and glyoxylate cycle pathway were determined. Results We annotated 50,808 Unigenes from the transcriptome of Chinese fir roots. Among differentially expressed genes, seven genes of phosphate transporter family and 17 genes of purple acid phosphatase family were up-regulated by Pi deficiency, two proteins of SPX domain were up-regulated and one was down-regulated. The metabolic pathways of the citric acid and glyoxylate cycle pathway were mapped, and the expression characteristics of the related Unigenes under different phosphorus treatments were analyzed. The genes involved in malic acid and citric acid synthesis were up-regulated, and the activities of the related enzymes were significantly enhanced under long-term Pi stress. The contents of citric acid and malic acid in the roots of Chinese fir increased after 30 days of Pi deficiency. Conclusion Chinese fir roots showed increased expression of genes related with phosphorus starvation, citrate and malate synthesis genes, increased content of organic acids, and enhanced activities of related enzymes under Pi deficiency. The results provide a new insight for revealing the molecular mechanism of adaption to Pi deficiency and the pathway of organic acid synthesis in Chinese fir roots.

Recently, a P-deficient diet caused rickets in commercial chicks within three days. This study aimed to investigate the duration of onset of rickets in chicks. Data were collected from 3–11 day old chicks raised on 88 commercial farms. Male day-old Arbor Acres Plus broilers (n = 450) were studied in three trials, with three to four treatments each. Each treatment used one of the following crumbled feeds: control feed (calcium (Ca): phosphorus (P)-1.41), slightly high Ca:P feed (SHCa:P, Ca:P-2.69), high Ca:P ratio, P deficient feed (HCa:P, Ca:P-3.08), and HCa:P feed plus 1.5% dicalcium phosphate (HCa:P + DP). Each treatment had three replicates with 15 birds each. Rickets was induced by HCa:P, and cured by HCa:P + DP, confirmed by gross anatomy, gait score, serum P concentration and growth performance. Lameness was not found in control groups, whereas, observed in the HCa:P groups as early as day 2.7 on commercial farms and day 3 in experimental farm. Serum P was reduced in HCa:P (p < 0.01). Bodyweight and feed intake started decreasing at day 3 on commercial farms and in all trials (p < 0.01). The duration of onset of hypophosphatemic rickets in broiler chicks fed HCa:P crumbled feed is approximately three days.

Background Phosphorus (P) is an essential macronutrient for plant growth that participates in a series of biological processes. Thus, P deficiency limits crop growth and yield. Although Stylosanthes guianensis (stylo) is an important tropical legume that displays adaptation to low phosphate (Pi) availability, its adaptive mechanisms remain largely unknown. Results In this study, differences in low-P stress tolerance were investigated using two stylo cultivars (‘RY2’ and ‘RY5’) that were grown in hydroponics. Results showed that cultivar RY2 was better adapted to Pi starvation than RY5, as reflected by lower values of relative decrease rates of growth parameters than RY5 at low-P stress, especially for the reduction of shoot and root dry weight. Furthermore, RY2 exhibited higher P acquisition efficiency than RY5 under the same P treatment, although P utilization efficiency was similar between the two cultivars. In addition, better root growth performance and higher leaf and root APase activities were observed with RY2 compared to RY5. Subsequent RNA-seq analysis revealed 8,348 genes that were differentially expressed under P deficient and sufficient conditions in RY2 roots, with many Pi starvation regulated genes associated with P metabolic process, protein modification process, transport and other metabolic processes. A group of differentially expressed genes (DEGs) involved in Pi uptake and Pi homeostasis were identified, such as genes encoding Pi transporter (PT), purple acid phosphatase (PAP), and multidrug and toxin extrusion (MATE). Furthermore, a variety of genes related to transcription factors and regulators involved in Pi signaling, including genes belonging to the PHOSPHATE STARVATION RESPONSE 1-like (PHR1), WRKY and the SYG1/PHO81/XPR1 (SPX) domain, were also regulated by P deficiency in stylo roots. Conclusions This study reveals the possible mechanisms underlying the adaptation of stylo to P deficiency. The low-P tolerance in stylo is probably manifested through regulation of root growth, Pi acquisition and cellular Pi homeostasis as well as Pi signaling pathway. The identified genes involved in low-P tolerance can be potentially used to design the breeding strategy for developing P-efficient stylo cultivars to grow on acid soils in the tropics.

International audience; White lupin produces cluster roots in response to phosphorus deficiency. Along the cluster root, numerous short rootlets successively appear, creating a spatial and temporal gradient of developmental stages that constitutes a powerful biological model to study the dynamics of the structural and functional evolution of these organs. The present study proposes a fine histochemical, transcriptomic and functional analysis of the rootlet development from its emergence to its final length. Between these two stages, the tissue structures of the rootlets were observed, the course of transcript expressions for the genes differentially expressed was monitored and some physiological events linked to Pi nutrition were followed. A switch between (i) a growing phase, in which a normal apical meristem is present and (ii) a specialized phase for nutrition, in which the rootlet is completely differentiated, was highlighted. In the final stage of its determinate growth, the rootlet is an organ with a very active metabolism, especially for the solubilization and absorption of several nutrients. This work discusses how the transition between a growing to a determinate state in response to nutritional stresses is found in other species and underlines the fundamental dilemma of roots between soil exploration and soil exploitation.

Phosphorus (P) is an important macronutrient for all lives, but it is also a finite resource. Therefore, it is important to understand how to increase the P availability and plant uptake. The endophytes can help host plants to improve P uptake and will be apparently affected by plant genotypes. To investigate the mechanism of root endophytes in promoting P uptake of peach rootstocks, we analyzed the variations of the root endophytic fungal and bacterial communities of peach rootstocks with different P efficiencies under high or low level of P addition. Results showed that Proteobacteria was the dominant bacterial phylum in the roots of all rootstocks under the two levels of P addition. At low P level, the abundance of Actinoplanes in phosphorus-inefficiency root system was apparently higher than that at high P level. Actinoplanes produced important secondary metabolites, improving the stress resistance of plants. Under high P condition, the abundance of Ferrovibrio was higher in Qing Zhou Mi Tao than in Du Shi. Fe oxides considerably reduced the availability of applied P, which partially explained why the P utilization in Qing Zhou Mi Tao is inefficient. Further, Ascomycota was the dominant fungal phylum in the roots of all rootstocks under different levels of P addition. The fungi community of roots varied in different rootstocks at each P level, but was similar for the same rootstock at different P levels, which indicated that genotype had a greater effect than P addition on the fungal community of peach rootstocks.

Phosphorus (P) deficiency is a common challenge in crop production because of its poor mobility through the soil. The root system plays a significant role in P absorption from the soil and is the initial indicator of low phosphorus. However, the phenotypic dynamics and longevity of cotton roots under phosphorus stress are still unknown. In this study, RhizoPot, an improvised in situ root observation device, was used to monitor the dynamics of root phenotypes of cotton seedlings under P-deficient (PD) and P-replete (PR) conditions. Low phosphorus stress reduced P absorption and accumulation in the roots, leading to low dry matter accumulation. Cotton seedlings responded to low P stress by increasing the number of lateral roots, specific root length, branch density, and root length density. Besides, the length of root hairs increased, and the lifespan of root hairs was prolonged. Low phosphorus stress also reduced the average diameter of roots, promoted root extension, expanded the root coverage area, and increased the range of phosphorus acquisition. Principal component analysis (PCA) revealed that the net root growth rate, root length density, root dry weight, phosphorus absorption efficiency, average root hair length, and taproot daily growth significantly influence cotton root architecture. Collectively, these results show that low phosphorus stress reduces the net growth rate of cotton seedling roots and restricts plant growth. Plants respond to phosphorus deficiency by extending the lifespan of root hairs and increasing specific root length and lateral root branch density. This change in root system architecture improves the adaptability of plants to low-phosphorus stress. The findings of this study may guide the selection of cotton varieties with efficient phosphorus utilization.

Arbuscular mycorrhizal fungi (AMF) are among plant-symbiotic fungi with higher plant roots. The applicability of AMF poses a strategy to minimize the deleterious effect of abiotic stress to enhance plant tolerance. Phosphorus is an essential macronutrient for plants, can cause toxic effects at low levels. Our target was to determine the mitigation effect of local inoculum of AMF on growth and metabolic activity of Zea mays under phosphorus levels. Phosphorus deficiency disturbed physiological performance however, AMF mitigated negative effects by enhancing the dry weight significantly (P < 0.05), P content and alkaline phosphatase in calcareous soil amended with P concentrations (from 15 to 120 mg P kg-1 soil), compared with non-inoculated plant. The maximum H+-ATPase activity was 28.13 µmol Pi-1ngP-1min in leaves of Zea mays in AM- inoculated soil and amended with 60 mg P kg-1soil. AMF enhanced antioxidant enzyme activities, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) together with their substrates glutathione (GSH) and ascorbic acid (AA), with concurrent reduction of lipid peroxidation and hydrogen peroxide content. Highest mycorrhizal colonization (88%) recorded in maize grown in 60 mg P kg-1 soil. Established data on morphological characters revealed AMF local isolates belong to four native spores related to genus Glomus, Acaulospora, Scutellospora and Entrophospora. Analysis of the genetic material confirmed that spores were related to Glomus mosseae and Acaulospora spinose. These findings demonstrate that root colonization by local AMP inoculum could ameliorate the phosphorus deficiency in calcareous soils collected from Southwestern coast of Egypt

The limited availability of phosphorus (P) in soils causes a major constraint in the productivity of potatoes, which requires increased knowledge of plant adaptation responses in this condition. In this study, six potato cultivars, namely, Agria, Lady Claire, Milva, Lilly, Sieglinde, and Verdi, were assessed for their responses on plant growth, leaf physiology, P use efficiency (PUE), and tuber quality with three P levels (Plow, Pmed, and Phigh). The results reveal a significant variation in the cultivars in response to different P availabilities. P-efficient cultivars, Agria, Milva, and Lilly, possessed substantial plant biomass, tuber yield, and high P uptake efficiency (PUpE) under low P supply conditions. The P-inefficient cultivars, Lady Claire, Sieglinde, and Verdi, could not produce tubers under P deprivation conditions, as well as the ability to efficiently uptake P under low-level conditions, but they were efficient in P uptake under high soil P conditions. Improved PUpE is important for plant tolerance with limited P availability, which results in the efficient use of the applied P. At the leaf level, increased accumulations of nitrate, sulfate, sucrose, and proline are necessary for a plant to acclimate to P deficiency-induced stress and to mobilize leaf inorganic phosphate to increase internal PUE and photosynthesis. The reduction in plant biomass and tuber yield under P-deficient conditions could be caused by reduced CO2 assimilation. Furthermore, P deficiency significantly reduced tuber yield, dry matter, and starch concentration in Agria, Milva, and Lilly. However, contents of tuber protein, sugars, and minerals, as well as antioxidant capacity, were enhanced under these conditions in these cultivars. These results highlight the important traits contributing to potato plant tolerance under P-deficient conditions and indicate an opportunity to improve the P efficiency and tuber quality of potatoes under deficient conditions using more efficient cultivars. Future research to evaluate molecular mechanisms related to P and sucrose translocation, and minimize tuber yield reduction under limited P availability conditions is necessary.

Transgenic plants containing genes of bacterial phytases represent one of the promising ways to solve the problem of phosphorus deficiency in the nutrition of plants and monogastric animals. Histidine acid phytase PaPhyC from Pantoea agglomerans has a high activity and represents a promising basis for the biotechnology of plants. In this study, the analysis of morphological characteristics, phytase activity, and phosphorus content in tissues of the earlier obtained, genetically modified Arabidopsis thaliana (L.) Heynh. plants producing extracellular phytase (PaPhyC) has been carried out. According to the obtained results, modified plants are able to grow on a medium supplemented with phytate as the sole source of phosphorus. Exterior characteristics (rosette diameter and area) of phytase-expressing plants grown on media containing phytate or inorganic phosphorus do not differ, which confirms that the plants use phytate as the phosphorus source. In the case of plant cultivation on a phytate-containing medium, a high phytase activity is observed in the cell walls of modified plants. The content of inorganic phosphorus in tissues of modified plants does not change in the case of their cultivation on the medium containing phytate as the sole source of phosphorus.

Soil phosphorus (P) availability, as well as shoot P status, may alter root morphology. However, how root morphological traits to light intensity under various P environments remains unknown. Maize (Zea mays L.) cultivar CD418 grew under nine P application rates (ranged from 0 to 300 mg P kg−1 soil, supplied as KH2PO4) under natural light intensity (NL) and low light intensity (LL, 40% of natural light intensity) in a naturally-lit rain-shed. Plant growth, P uptake, and responses of root morphological traits (i.e. total root length, root surface area, and proportion of

Breeder herd productivity can be severely reduced by dietary phosphorus (P) deficiency. The performance of small groups of P-deficient (Pdefic) or P-supplemented (Psupp) breeder cows was studied over 5 annual cycles while grazing C4 grass-Stylosanthes pastures at a site in the seasonally dry tropics of northern Australia. Soils contained c. 4 ppm of bicarbonate extractable P. Plasma inorganic P concentrations (PIP) during the wet season indicated that the Pdefic cows were deficient in P in 4 years and marginal in one year. Annual liveweight (LW) changes ranged widely between annual cycles from −71 to +13 kg in Pdefic cows and from +4 to +44 kg/head in Psupp cows. The LW responses to increased dietary P ranged from −9 to +115 kg, were greatest in years when LW losses by the Pdefic cows were greatest, and were associated with low-rainfall years. LW gains of calves suckling Psupp cows (mean 0.86 kg/d) tended to be higher (range 0.01-0.17 kg/d; mean 0.09 kg/d) than those of calves suckling Pdefic cows, but were significantly (P = 0.03) higher in only one year. Reconception appeared to be higher in Psupp than Pdefic cows during the 2 years of lower rainfall. Overall, the results indicated that responses to P supplementation by breeders grazing P-deficient pastures can vary widely between years. Therefore, the response in any one year may not reliably indicate responses in the longer term. Resumen La deficiencia de fósforo (P) en la dieta puede reducir severamente la productividad de las vacas reproductoras. En una zona de clima tropical estacional seco en el norte de Australia, durante cinco ciclos anuales se estudió el rendimiento de este tipo de vacas deficientes en P (Pdefic) o suplementadas con P (Psupl), en pasturas de Stylosanthes y gramíneas C4. El suelo tenía una concentración aproximada de 4 ppm de P soluble (bicarbonato). Las concentraciones de P inorgánico en el plasma (PIP) determinadas en época lluviosa indicaron que las vacas Pdefic presentaron deficiencia de P durante 4 años y suficiencia marginal de P en un año. El cambio anual de peso vivo varió ampliamente entre 4 y 44 kg/animal en las vacas Psupl y entre −71 y +13 kg en las vacas Pdefic. En los años con pocas lluvias la respuesta a la dieta con Psupl varió entre −9 y +115 kg, y fue mayor en las vacas Pdefic. El crecimiento de los terneros amamantados por las vacas Psupl (0.86 kg/dia) tendió a ser mayor (rango 0.01‒0.17, promedio 0.09 kg/dia) que en aquellos de las vacas Pdefic, pero esta diferencia fue significativa (P = 0.03) solo en uno de los cinco años experimentales. La reconcepción fue más alta en las vacas Psupl que en las Pdefic durante los dos años de menor precipitación. La amplia variación entre años en las concentraciones de PIP y los efectos de la deficiencia de P estuvieron ligadas a una alta variación en la lluvia anual y estacional. Los resultados mostraron que la respuesta de las vacas en pasturas deficientes en P a suplemento de P puede variar ampliamente entre años. Por lo tanto, la respuesta en un período determinado no garantiza la misma tendencia en el largo plazo.

Phosphorus (P) is a major constituent of biomolecules in plant cells, and is an essential plant macronutrient. Low phosphate (Pi) availability in soils is a major constraint on plant growth. Although a complex variety of plant responses to Pi starvation has been well documented, few studies have integrated both global transcriptome and metabolome analyses to shed light on molecular mechanisms underlying metabolic responses to P deficiency. This study is the first time to investigate global profiles of metabolites and transcripts in soybean (Glycine max) roots subjected to Pi starvation through targeted liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS/MS) and RNA-sequencing analyses. This integrated analysis allows for assessing coordinated transcriptomic and metabolic responses in terms of both pathway enzyme expression and regulatory levels. Between two Pi availability treatments, a total of 155 metabolites differentially accumulated in soybean roots, of which were phosphorylated metabolites, flavonoids and amino acids. Meanwhile, a total of 1644 differentially expressed genes (DEGs) were identified in soybean roots, including 1199 up-regulated and 445 down-regulated genes. Integration of metabolome and transcriptome analyses revealed Pi starvation responsive connection between specific metabolic processes in soybean roots, especially metabolic processes involving phosphorylated metabolites (e.g., phosphorylated lipids and nucleic acids). Taken together, this study suggests that complex molecular responses scavenging internal Pi from phosphorylated metabolites are typical adaptive strategies soybean roots employ as responses to Pi starvation. Identified DEGs will provide potential target region for future efforts to develop P-efficient soybean cultivars.

This study aimed to evaluate the effects of phosphorus (P) deficiency on the lateral root growth of Fraxinus mandshurica seedlings and to reveal the potential molecular mechanisms involved. F. mandshurica seedlings were treated with various concentrations of P (0, 0.5, 1, and 2 mM KH₂PO₄) for 15 d. The growth of lateral roots was quantified by the number of lateral roots, total root length, total root surface area, and root : shoot ratio. Additionally, the levels of endogenous hormones and acid phosphatase were determined in the lateral roots of F. mandshurica seedlings using enzyme‐linked immunosorbent assay (ELISA). The transcription of 17 FmWRKYs and FmPHR1 was detected in the lateral roots of F. mandshurica seedlings using quantitative real‐time PCR (qRT‐PCR). F. mandshurica seedlings under P deficiency (0 mM) exhibited significantly higher number of lateral roots, total root length, total root surface area, and root : shoot ratio than those under P supply. P deficiency significantly decreased the levels of indole‐3‐acetic acid, brassinolide, and ethylene, and increased the levels of gibberellins 3, cytokinin, abscisic acid, and acid phosphatase in the lateral roots of F. mandshurica seedlings when compared to seedlings with P supply. In addition, the transcription of four FmWRKYs, including FmWRKY6, FmWRKY23, FmWRKY44, and FmWRKY71, as well as FmPHR1 were significantly higher in the lateral roots of F. mandshurica seedlings under P deficiency compared to seedlings treated with 1 mM P. Phosphorus deficiency promoted the lateral root growth of F. mandshurica seedlings and this process may be associated with the up‐regulation of FmWRKY6, FmWRKY23, FmWRKY44, FmWRKY71, and FmPHR1.

Rhizosphere colonization is a requirement for field applications of plant growth-promoting rhizobacteria (PGPR). Complex signal exchanges and mutual recognition occur between microbes and plants. Here, the phosphate-solubilizing strain Pseudomonas sp. P34, which is a type of PGPR with affinity to wheat, was isolated from a wheat rhizosphere via wheat germ agglutinin. A pTR102 plasmid harboring the luciferase luxAB gene was transferred into P34. The labeled strain (P34-L) was then used to track the temporal and spatial characteristics of rhizosphere colonization and examine the effects of colonization on wheat development. The transcript levels of the phosphate transporter gene TaPT4, a phosphorus deficiency indicator, in wheat roots were monitored by quantitative reverse transcription PCR (qRT-PCR). The results indicated that P34-L could survive within the wheat rhizosphere for a long time and colonize new spaces in the wheat rhizosphere following the elongation of wheat roots. Compared with uninoculated wheat plants, plants inoculated with P34-L exhibited significantly increased phosphorus accumulation in the leaves; seedling and root weight; total root length; root projection area; root surface area; and number of root tips, forks, and crossings, thus demonstrating the great value of applying this strain in wheat production by promoting root growth and dry matter accumulation. The downregulation of TaPT4 transcript levels in the wheat roots also suggested that a high-phosphorus environment was established by P34-L. These results lay a foundation for further research on the relationships between PGPR and their host plants. Moreover, a potentially ideal biofertilizer-producing strain for use in sustainable agriculture was developed.

This experiment was carried out in pots in a greenhouse to evaluate the effects of arbuscular mycorrhizal fungi (Funneliformis mosseae, Rhizophagus intraradices and Rhizophagus fasciculatus) on carob plant performance under different levels of phosphate fertilization. Non-mycorrhizal (NMyc) and mycorrhizal (Myc) carob plants were subjected to three levels of phosphate fertilization, L1 (0 mg P kg−1 soil), L2 (25 mg P kg−1 soil) and L3 (100 mg P kg−1 soil). Results showed that under L1 and L2 P-fertilization levels, arbuscular mycorrhizal symbiosis significantly improved growth and biomass production of carob plants. Moreover, mineral nutrient (P, K, Na and Ca) acquisition, photosynthetic activity (Fv/Fm), stomatal conductance, total chlorophyll content, and soluble sugar accumulation were also strongly improved in Myc plants in comparison with NMyc ones. Under L1 P-fertilization level, Myc plants showed strongly increased acid phosphatase activity in roots and in the rhizospheric soil than NMyc plants. Furthermore, Myc plants maintained high membrane integrity (over 80%) and low hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents, associated with increased activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (G-POD), and catalase (CAT) compared to NMyc plants. However, high phosphorus input (L3) negatively affected root colonization and mycorrhizal plant performance. Thus, carob plants associated with Funneliformis mosseae performed best under phosphorus deficiency and were the least sensitive to the variations of phosphorus input levels.

SUMMARY Inorganic phosphorus (Pi) is an essential element in numerous metabolic reactions and signaling pathways, but the molecular details of these pathways remain largely unknown. In this study, metabolite profiles of maize (Zea mays L.) leaves and roots were compared between six low‐Pi‐sensitive lines and six low‐Pi‐tolerant lines under Pi‐sufficient and Pi‐deficient conditions to identify pathways and genes associated with the low‐Pi stress response. Results showed that under Pi deprivation the concentrations of nucleic acids, organic acids and sugars were increased, but that the concentrations of phosphorylated metabolites, certain amino acids, lipid metabolites and nitrogenous compounds were decreased. The levels of secondary metabolites involved in plant immune reactions, including benzoxazinoids and flavonoids, were significantly different in plants grown under Pi‐deficient conditions. Among them, the 11 most stable metabolites showed significant differences under low‐ and normal‐Pi conditions based on the coefficient of variation (CV). Isoleucine and alanine were the most stable metabolites for the identification of Pi‐sensitive and Pi‐resistant maize inbred lines. With the significant correlation between morphological traits and metabolites, five low‐Pi‐responding consensus genes associated with morphological traits and simultaneously involved in metabolic pathways were mined by combining metabolites profiles and genome‐wide association study (GWAS). The consensus genes induced by Pi deficiency in maize seedlings were also validated by reverse‐transcription quantitative polymerase chain reaction (RT‐qPCR). Moreover, these genes were further validated in a recombinant inbred line (RIL) population, in which the glucose‐6‐phosphate‐1‐epimerase encoding gene mediated yield and correlated traits to phosphorus availability. Together, our results provide a framework for understanding the metabolic processes underlying Pi‐deficient responses and give multiple insights into improving the efficiency of Pi use in maize., Significance statement Metabolite profiling and GWAS were applied to reveal maize low‐Pi response mechanisms.

Upland rice production is often constrained by phosphorus deficiency (P) and drought events. Methods are needed to maximize P use efficiency, while promoting deep root development to mitigate drought. This study evaluates micro-dose P placement as a technique to enhance drought resilience of upland rice, thereby hypothesizing that P placement enhances deep root development, stimulated by the local P supply in the planting hole, compared to broadcast P. Two pot experiments were conducted using P deficient upland soil in Tanzania (Expt.1) and Madagascar (Expt.2), with factorial combinations of P doses (control and two P levels), application method (placement versus broadcast), rice varieties (DJ123 & NERICA4) and water regimes (field capacity and drying periods). Micro-dose P placement strongly boosted the establishment of upland rice and enhanced P recovery rates (4- to 5-fold) and fertilizer use efficiency (9- to 14-fold) compared to broadcast P. Micro-dose P placements significantly enhanced the fraction of roots found at largest depth (> 30 cm, Expt. 1; >15 cm, Expt. 2) by 22- to 33 %. Surprisingly, shoot P concentrations were markedly lower under P placement than under broadcast at equivalent P doses or equivalent biomass, indicating a Piper-Steenbjerg effect. This study is first in showing the enhanced deep rooting after basal P placement, and suggests replication at field scale where subsurface moisture may yield stronger benefits than in pots. The depleted shoot P concentrations induced by vigorous plant establishment under P placement may, however, counteract benefits at later growth stages and need further attention.

Phosphorus (P) is an essential macronutrient for plant growth, development and production. However, little is known about the effects of P deficiency on nutrient absorption, photosynthetic apparatus performance and antioxidant metabolism in citrus. Seedlings of ‘sour pummelo’ (Citrus grandis) were irrigated with a nutrient solution containing 0.2 mM (Control) or 0 mM (P deficiency) KH2PO4 until saturated every other day for 16 weeks. P deficiency significantly decreased the dry weight (DW) of leaves and stems, and increased the root/shoot ratio in C. grandis but did not affect the DW of roots. The decreased DW of leaves and stems might be induced by the decreased chlorophyll (Chl) contents and CO2 assimilation in P deficient seedlings. P deficiency heterogeneously affected the nutrient contents of leaves, stems and roots. The analysis of Chl a fluorescence transients showed that P deficiency impaired electron transport from the donor side of photosystem II (PSII) to the end acceptor side of PSI, which showed a greater impact on the performance of the donor side of PSII than that of the acceptor side of PSII and photosystem I (PSI). P deficiency increased the contents of ascorbate (ASC), H2O2 and malondialdehyde (MDA) as well as the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in leaves. In contrast, P deficiency increased the ASC content, reduced the glutathione (GSH) content and the activities of SOD, CAT, APX and monodehydroascorbate reductase (MDHAR), but did not increase H2O2 production, anthocyanins and MDA content in roots. Taking these results together, we conclude that P deficiency affects nutrient absorption and lowers photosynthetic performance, leading to ROS production, which might be a crucial cause of the inhibited growth of C. grandis.

Low-phosphorus stress (LPS) and pathogen attack are two important stresses frequently experienced by plants in their natural habitats, but how plant respond to them coordinately remains under-investigated. Here, we demonstrate that CaWRKY58, a known negative regulator of the pepper (Capsicum annuum) response to attack by Ralstonia solanacearum, is upregulated by LPS. Virus-induced gene silencing (VIGS) and overexpression of CaWRKY58 in Nicotiana benthamiana plants in combination with chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSA) demonstrated that CaWRKY58 positively regulates the response of pepper to LPS by directly targeting and regulating genes related to phosphorus-deficiency tolerance, including PHOSPHATE STARVATION RESPONSE1 (PHR1). Yeast two-hybrid assays revealed that CaWRKY58 interacts with a 14-3-3 protein (Ca14-3-3); this interaction was confirmed by pull-down, bimolecular fluorescence complementation (BiFC), and microscale thermophoresis (MST) assays. The interaction between Ca14-3-3 and CaWRKY58 enhanced the activation of PHR1 expression by CaWRKY58, but did not affect the expression of the immunity-related genes CaNPR1 and CaDEF1, which are negatively regulated by CaWRKY58 in pepper upon Ralstonia solanacearum inoculation. Collectively, our data indicate that CaWRKY58 negatively regulates immunity against Ralstonia solanacearum, but positively regulates tolerance to LPS and that Ca14-3-3 transcriptionally activates CaWRKY58 in response to LPS.

Phosphorus is an essential macronutrient for plant growth and development. Root system architecture (RSA) affects a plant's ability to obtain phosphate, the major form of phosphorus that plants uptake. In this review, I first consider the relationship between RSA and plant phosphorus-acquisition efficiency, describe how external phosphorus conditions both induce and impose changes in the RSA of major crops and of the model plant Arabidopsis, and discuss whether shoot phosphorus status affects RSA and whether there is a universal root developmental response across all plant species. I then summarize the current understanding of the molecular mechanisms governing root developmental responses to phosphorus deficiency. I also explore the possible reasons for the inconsistent results reported by different research groups and comment on the relevance of some studies performed under laboratory conditions to what occurs in natural environments.

Mungbean (Vigna radiata L. Wilczek) is an annual grain legume crop affected by low availability of phosphorus. Phosphorus deficiency mainly affects the growth and development of plants along with changes in root morphology and increase in root-to-shoot ratio. Deciphering the genetic basis of phosphorus use efficiency (PUE) traits can benefit our understanding of mungbean tolerance to low-phosphorus condition. To address this issue, 144 diverse mungbean genotypes were evaluated for 12 PUE traits under hydroponics with optimum- and low-phosphorus levels. The broad sense heritability of traits ranged from 0.63 to 0.92 and 0.58 to 0.92 under optimum- and low-phosphorus conditions, respectively. This study, reports for the first time such a large number of genome wide Single nucleotide polymorphisms (SNPs) (76,160) in mungbean. Further, genome wide association study was conducted using 55,634 SNPs obtained by genotyping-by-sequencing method. The results indicated that total 136 SNPs shared by both GLM and MLM models were associated with tested PUE traits under different phosphorus regimes. We have identified SNPs with highest p value (–log10(p)) for some traits like, TLA and RDW with p value (–log10(p)) of more than 6.0 at LP/OP and OP condition. We have identified nine SNPs (three for TLA and six for RDW trait) which was found to be present in chromosomes 8, 4, and 7. One SNP present in Vradi07g06230 gene contains zinc finger CCCH domain. In total, 71 protein coding genes were identified, of which 13 genes were found to be putative candidate genes controlling PUE by regulating nutrient uptake and root architectural development pathways in mungbean. Moreover, we identified three potential candidate genes VRADI11G08340, VRADI01G05520, and VRADI04G10750 with missense SNPs in coding sequence region, which results in significant variation in protein structure at tertiary level. The identified SNPs and candidate genes provide the essential information for genetic studies and marker-assisted breeding program for improving low-phosphorus tolerance in mungbean.

Low phosphate (Pi) availability limits crop growth and yield in acid soils. Although root-associated acid phosphatases (APases) play an important role in extracellular organic phosphorus (P) utilization, they remain poorly studied in soybean (Glycine max), an important legume crop. In this study, dynamic changes in intracellular (leaf and root) and root-associated APase activities were investigated under both Pi-sufficient and Pi-deficient conditions. Moreover, genome-wide identification of members of the purple acid phosphatase (PAP) family and their expression patterns in response to Pi starvation were analyzed in soybean. The functions of both GmPAP7a and GmPAP7b, whose expression is up regulated by Pi starvation, were subsequently characterized. Phosphate starvation resulted in significant increases in intracellular APase activities in the leaves after 4 days, and in root intracellular and associated APase activities after 1 day, but constant increases were observed only for root intracellular and associated APase activities during day 5–16 of P deficiency in soybean. Moreover, a total of 38 GmPAP members were identified in the soybean genome. The transcripts of 19 GmPAP members in the leaves and 17 in the roots were upregulated at 16 days of P deficiency despite the lack of a response for any GmPAP members to Pi starvation at 2 days. Pi starvation upregulated GmPAP7a and GmPAP7b, and they were subsequently selected for further analysis. Both GmPAP7a and GmPAP7b exhibited relatively high activities against adenosine triphosphate (ATP) in vitro. Furthermore, overexpressing GmPAP7a and GmPAP7b in soybean hairy roots significantly increased root-associated APase activities and thus facilitated extracellular ATP utilization. Taken together, these results suggest that GmPAP7a and GmPAP7b might contribute to root-associated APase activities, thus having a function in extracellular ATP utilization in soybean.