Pi Content Research Articles

Foliar P nutrition of European beech (Fagus sylvatica L.) depends on the season but remains unaffected by co-cultivation with silver fir (Abies alba Mill.)

Beech (Fagus sylvatica) and silver fir (Abies alba) are often cultivated in mixed stands and, hence, compete for water and nutrients. Besides nitrogen (N), also phosphorus (P) is an important nutrient for growth and development. Beech trees in Central Europe grow on both P-poor and P-rich soils, thereby showing similar growth and low variation in foliar P. The central aim of the present study was to test the hypothesis that variations in foliar P contents of beech are driven by seasonal changes rather than by the competition with silver fir. It was further hypothesized that P contents in silver fir needles depend on needle age and forest site. To test these hypotheses, P contents and P fractions, i.e. organic-bound P (Porg) and inorganic phosphate P (Pi), were measured in the foliage of beech trees from pure beech and mixed beech/silver fir plots as well as in needles of silver fir of the mixed plots. The forest sites investigated are located in Central Europe in the Black Forest, Germany, and in Croatia near the south-eastern distribution limit of beech and are all poor in plant-available soil P. The analyses showed that the main driver of P contents and P fractions in beech leaves at all forest sites is the season and that competition with silver fir had no effect. Hence, the present results demonstrate the high plasticity of beech trees to adapt to both poor plant-available soil P and competition with silver fir. Total P contents of silver fir needles were higher at the Croatian site compared to the Black Forest sites and originated from higher foliar Pi contents. One third of the P present in current-year needles in late summer was remobilized and exported until the needles reached the age of 1 year. The difference in P contents between current-year and 1-year-old needles can be seen as the amount of P resorbed from 1-year-old needles in summer during the generation of new needles to support the P demand of current-year needles for growth and development.

Modulation of Shoot Phosphate Level and Growth by PHOSPHATE1 Upstream Open Reading Frame.

Inorganic orthophosphate (Pi) is an essential nutrient for plant growth, and its availability strongly impacts crop yield. PHOSPHATE1 (PHO1) transfers Pi from root to shoot via Pi export into root xylem vessels. In this work, we demonstrate that an upstream open reading frame (uORF) present in the 5' untranslated region of the Arabidopsis (Arabidopsis thaliana) PHO1 inhibits its translation and influences Pi homeostasis. The presence of the uORF strongly inhibited the translation of a PHO1 5'UTR-luciferase construct in protoplasts. A point mutation removing the PHO1 uORF (ΔuORF) in transgenic Arabidopsis resulted in increased association of its mRNA with polysomes and led to higher PHO1 protein levels, independent of Pi availability. Interestingly, deletion of the uORF led to higher shoot Pi content and was associated with improved shoot growth under low external Pi supply and no deleterious effects under Pi-sufficient conditions. We further show that natural accessions lacking the PHO1 uORF exhibit higher PHO1 protein levels and shoot Pi content. Increased shoot Pi content was linked to the absence of the PHO1 uORF in a population of F2 segregants. We identified the PHO1 uORF in genomes of crops such as rice (Oryza sativa), maize (Zea mays), barley (Hordeum vulgare), and wheat (Triticum aesativum), and we verified the inhibitory effect of the rice PHO1 uORF on translation in protoplasts. Our work suggests that regulation of PHO1 expression via its uORF might be a genetic resource useful-both in natural populations and in the context of genome editing-toward improving plant growth under Pi-deficient conditions.

Phosphate excess increases susceptibility to pathogen infection in rice.

Phosphorus (P) is an essential nutrient for plant growth and productivity. Due to soil fixation, however, phosphorus availability in soil is rarely sufficient to sustain high crop yields. The overuse of fertilizers to circumvent the limited bioavailability of phosphate (Pi) has led to a scenario of excessive soil P in agricultural soils. Whereas adaptive responses to Pi deficiency have been deeply studied, less is known about how plants adapt to Pi excess and how Pi excess might affect disease resistance. We show that high Pi fertilization, and subsequent Pi accumulation, enhances susceptibility to infection by the fungal pathogen Magnaporthe oryzae in rice. This fungus is the causal agent of the blast disease, one of the most damaging diseases of cultivated rice worldwide. Equally, MIR399f overexpression causes an increase in Pi content in rice leaves, which results in enhanced susceptibility to M. oryzae. During pathogen infection, a weaker activation of defence‐related genes occurs in rice plants over‐accumulating Pi in leaves, which is in agreement with the phenotype of blast susceptibility observed in these plants. These data support that Pi, when in excess, compromises defence mechanisms in rice while demonstrating that miR399 functions as a negative regulator of rice immunity. The two signalling pathways, Pi signalling and defence signalling, must operate in a coordinated manner in controlling disease resistance. This information provides a basis to understand the molecular mechanisms involved in immunity in rice plants under high Pi fertilization, an aspect that should be considered in management of the rice blast disease.

Enhanced Vitamin C Production Mediated by an ABA-Induced PTP-like Nucleotidase Improves Plant Drought Tolerance in Arabidopsis and Maize

Abscisic acid (ABA) is a key phytohormone that mediates environmental stress responses. Vitamin C, or L-ascorbic acid (AsA), is the most abundant antioxidant protecting against stress damage in plants. How the ABA and AsA signaling pathways interact in stress responses remains elusive. In this study, we characterized the role of a previously unidentified gene, PTPN (PTP-like Nucleotidase) in plant drought tolerance. In Arabidopsis, (AtPTPN was expressed in multiple tissues and upregulated by ABA and drought treatments. Loss-of-function mutants of AtPTPN were hyposensitive to ABA but hypersensitive to drought stresses, whereas plants with enhanced expression of AtPTPN showed opposite phenotypes to . Overexpression of maize PTPN (ZmPTPN) promoted, while knockdown of ZmPTPN inhibited plant drought tolerance, indicating conserved and positive roles of PTPN in plant drought tolerance. We found that both AtPTPN and ZmPTPN release Pi by hydrolyzing GDP/GMP/dGMP/IMP/dIMP, and that AtPTPN positively regulated AsA production via endogenous Pi content control. Consistently, overexpression of VTC2, the rate-limiting synthetic enzyme in AsA biosynthesis, promoted AsA production and plant drought tolerance, and these effects were largely dependent on AtPTPN activity. Furthermore, we demonstrated that the heat shock transcription factor HSFA6a directly binds the AtPTPN promoter and activates AtPTPN expression. Genetic analyses showed that AtPTPN is required for HSFA6a to regulate ABA and drought responses. Taken together, our data indicate that PTPN-mediated crosstalk between the ABA signaling and AsA biosynthesis pathways positively controls plant drought tolerance.

Dry sliding tribological properties of PI/UHMWPE blends for high speed application

PI/UHMWPE blends are going to be used as the bush material of sliding bearings under high speed dry condition in one project. Prior to the fabrication of these bearings, the tribological properties PI/UHMWPE blends with various component ratio under the specific service condition was investigated by using a pin-on-disk tribometer. The results revealed that the compression modulus of PI/UHMWPE blends increases with the increase in PI content. Furthermore, the coefficient of friction and wear rate decrease firstly and then increase slightly with the increase in PI content, both of which reach the minimum value when PI content is 70%. The analyses of transfer membrane indicate that both of UHMWPE and PI can transfer to the metal counterface, while the increase of PI content is more conducive to the increase of transfer membrane.

Aminobisphosphonate-treated ewes as a model of osteonecrosis of the jaw and of dental implant failure.

Bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) and dental implant failure are two negative side effects of chronic aminoBP treatment. Eleven ovariectomized (OVX) ewes and four ewes subjected to sham surgery (SHAM) were treated as follows: OVX (n=5): OVX plus saline solution; zoledronic acid-treated group (ZOL) (n=6): OVX plus ZOL; SHAM (n=4): SHAM plus saline solution. Extraction of the first upper molar was performed at 1 year, dental implant placement at 2 years, and sacrifice at 28 months. Implants remained in place in SHAM and OVX ewes but were lost in all ZOL ewes. ZOL sheep (2/6) showed inflammation and necrotic bone at mandibular region. No differences in serum calcium (Ca), inorganic phosphate (Pi) or 25-hydroxyvitamin D were observed, whereas bone alkaline phosphatase levels decreased in the three studied groups (P<0.05). The significantly lowest levels of carboxy-terminal telopeptide of type I collagen were observed in ZOL (P<0.05), and showed no differences between SHAM and OVX. OVX showed the lowest and ZOL the highest Ca and Pi contents in femur and maxilla (P<0.05). Bone volume (BV/TV%) and iliac crest were similar at baseline and at month 4. At the end of the study, BV/TV%, proximal femur and hemi-mandible bone mineral content and bone mineral density, and trabeculae number were similar in SHAM and ZOL, and lower in OVX (P<0.05). All ZOL-treated ewes on a schedule similar to that used in cancer patients showed extensive suppression of bone remodeling and implant failure. Some of the ZOL ewes developed BRONJ.

International Study of Teacher Professional Identity

Introduction. The article is devoted to the international research project “Professional Identity of a Modern Teacher” (2013–2018). Formed professional identity is the key to self-realization and professional and personal development. As well as a developed and formed professional identity ensures successful professional activity, which is very important for the development of society. The purpose of the article is to reveal the content of the professional identity of the modern teacher. Materials and Methods. The main stages and empirical base of research are presented. Based on the analysis of the results of the survey according to the method “Professional Identity of a Higher School Teacher” and taking into account the specifics of the work of a school teacher, in 2017. The structural model of the teacher’s PI content was clarified, the content of the structural components of the model was adjusted, and the teacher’s Professional Identity methodology was created (authors A. Shpona, M. Widner, E. Ermolaeva, T. Bogdanova, S. Silchenkova) Statistical methods were used to analyze the data obtained: a comparison of the groups of respondents by the components under study using the Mann – Whitney U-test, correlation analysis, descriptive statistics, tabular and graphical methods. Results. The main results are given: a teacher’s professional identity model, its structural components, average values of professional identity by blocks for Latvian, Russian and Belarusian samples. Discussion and Conclusions. An international study showed that many Russian and Latvian teachers work with the awareness of the high mission of their professional activities, are aimed at developing students’ competence, cultural and value orientations, and set themselves the task of raising the level of education in society as a whole.

Registration of USDA‐N6003LP Soybean Germplasm with Low Seed Phytate

Soybean [Glycine max (L.) Merr.] meal is the main source of protein in poultry and swine rations worldwide. Phytate, the main storage form of phosphorous in soybean meal, is largely indigestible by monogastric animals and, thus, a major concern both for nutrition and for environmental pollution. USDA‐N6003LP (Reg. no. GP‐435, PI 689999) is a low‐phytate (LP) determinate, lodging‐resistant early maturity group (MG) VI soybean germplasm developed and released jointly by the USDA‐ARS and the North Carolina Agricultural Research Service. USDA‐N6003LP is derived from a backcross (BC1) between recurrent parent ‘NC‐Roy’ and LP donor line USDA CX1834. NC‐Roy is a high‐yielding MG VI cultivar adapted to the southern United States. USDA‐N6003LP has 60% lower phytate and 4.8 times higher inorganic phosphorus (Pi) contents in its seed than the seed of NC‐Roy. It matures approximately 5 d earlier and has larger seed size and better lodging resistance (P &lt; 0.05) compared with NC‐Roy. Across 17 environments in the USDA Uniform Soybean Tests, Southern States and over four local yield trials in North Carolina, USDA‐N6003LP yielded 91 and 97% of NC‐Roy, respectively. Field emergences of this line in four tests in NC were 79 to 80% compared with 89 to 90% for NC‐Roy. USDA‐N6003LP is the first early MG VI LP germplasm release with good agronomic performance and relatively normal field emergence. It will be useful as parental stock for soybean breeders interested in developing LP soybean cultivars.

Development of multifunctional Overhauser-enhanced magnetic resonance imaging for concurrent in vivo mapping of tumor interstitial oxygenation, acidosis and inorganic phosphate concentration

Tumor oxygenation (pO2), acidosis (pH) and interstitial inorganic phosphate concentration (Pi) are important parameters of the malignant behavior of cancer. A noninvasive procedure that enables visualization of these parameters may provide unique information about mechanisms of tumor pathophysiology and provide clues to new treatment targets. In this research, we present a multiparametric imaging method allowing for concurrent mapping of pH, spin probe concentration, pO2, and Pi using a single contrast agent and Overhauser-enhanced magnetic resonance imaging technique. The developed approach was applied to concurrent multifunctional imaging in phantom samples and in vivo in a mouse model of breast cancer. Tumor tissues showed higher heterogeneity of the distributions of the parameters compared with normal mammary gland and demonstrated the areas of significant acidosis, hypoxia, and elevated Pi content.

Synthesis of polyimide-modified carbon nanotubes as catalyst for organic pollutant degradation via production of singlet oxygen with peroxymonosulfate without light irradiation

Polyimide-modified carbon nanotubes (PI/CNTs) were synthesized via a solvent-free thermal method and used as a metal-free catalyst to activate peroxymonosulfate for organic contaminant degradation without light irradiation. The characterization results suggested that PI was loaded onto the surface of CNTs. The catalytic ability of the PI/CNTs was strongly correlated with the content of PI in the catalysts. The PI/CNTs (22% of PI) showed the highest catalytic efficiency for organic pollutant degradation at room temperature. The degradation efficiency of acid orange 7 (AO7) dye was significantly enhanced to 98.9% within 15 min, compared to the efficiency of 2.2% exhibited by pure PI. The radical quenching tests and electron paramagnetic resonance spectrometry proved that singlet oxygen, instead of hydroxyl radicals or sulfate radicals, played a dominant role during the catalytic oxidation of AO7. The influences of operation parameters including temperature and catalyst amount were investigated. The PI/CNTs metal-free catalyst exhibited high catalytic activity under a broad range of pH values. The recycling study of four repeated reactions demonstrated good stability of the PI/CNTs. This work provided a promising metal-free catalyst for degradation of organic pollutants in aqueous solutions, contributing to the development of green materials for sustainable remediation.

Phosphate supply influenced the growth, yield and expression of PHT1 family phosphate transporters in seven millets.

Phosphate starvation altered the root morphology and phosphate uptake with the induction of PHT1 family transporter genes in root and shoot tissues of seven millets. Millets are nutrient-rich cereals majorly cultivated in Asia and Africa. Foxtail millet (FoxM), pearl millet (PeaM), finger millet (FinM), kodo millet (KodM), little millet (LitM), proso millet (ProM), and barnyard millet (BarM) were examined for the influence of external phosphorous (P) supply on phenotypic traits, P uptake, yield, and PHosphate Transporter1 (PHT1) family gene expression. Millet seedlings grown under low Pi condition (LPC) produced significantly lower mean values for all traits except for lateral root length (LRL) and lateral root number (LRN) which were increased under LPC. Under LPC, seed weight (SW) also reduced by > 75% and had significantly lower levels of total P (TP) and Pi contents in leaf and root tissues. Expression dynamics of 12 PHT1 family (PHT1;1-1;12) transporters genes were analyzed in 7 millets. PHT1;2 has been found to be a constitutive transporter gene in all millets. Under LPC, root tissues showed the overexpression of PHT1;2, 1;3, 1;4 and 1;9 in FoxM, PHT1;1, 1;2, 1;3, 1;4, 1;8 and 1;10 in PeaM, PHT1;2 and 1;3 in FinM and ProM and PHT1;3, 1;6 and 1;11 in BarM. In leaf, LPC induced the expression of PHT1;3, 1;4 and 1;6 in FoxM, PHT1;2, 1;3, 1;4 and 1;8 in PeaM, PHT1;2, 1;3 and 1;4 in FinM and KodM, PHT1;2 in LitM and PHT1;4 in ProM and BarnM. This comprehensive study on the influence of P in phenotype, physiology, and molecular responses may help to improve the P uptake and its use efficiency of millets in future.

Lipid remodeling under acidic conditions and its interplay with low Pi stress in Arabidopsis

Key messageHere we show that accumulation of galactose-containing lipids in plastid membranes in shoots and the other membranes in roots maintains Arabidopsis growth under acidic stress and acidic phosphate deficiency.Soil acidification and phosphate deficiency are closely related to each other in natural environments. In addition to the toxicity of high proton concentrations, acid soil can lead to imbalances of ion availability and nutritional deficiencies, including inorganic phosphate (Pi). Among plants, activation of non-phosphorus-containing galactolipid, digalactosyldiacylglycerol (DGDG), synthesis concomitant with phospholipid degradation, namely membrane lipid remodeling, is crucial for coping with Pi starvation. However, regulation mechanisms of membrane lipid composition during acidic stress have not been clarified. Here, we investigated lipid metabolism in Arabidopsis thaliana grown under acidic stress with or without Pi. Under Pi-sufficient acidic conditions, DGDG was increased in shoot membranes, and some Pi starvation–responsive genes that are involved in lipid remodeling were upregulated without reducing Pi content in leaves. In contrast, under acidic Pi deficiency, membrane lipid remodeling in roots was partially repressed at a lower external pH. Nevertheless, phenotypic comparison between wild type and the double mutant of MGD2/3, which are responsible for DGDG accumulation during Pi starvation, indicated that the complete absence of lipid remodeling in roots resulted in a loss of tolerance to Pi deficiency rather specifically under acidic conditions. This result suggested important physiological roles of galactolipid-enriched membranes under acidic Pi deficiency.

The high-affinity transporter BnPHT1;4 is involved in phosphorus acquisition and mobilization for facilitating seed germination and early seedling growth of Brassica napus

BackgroundSeed germination and seedling establishment are two of the most critical phases in plant development. However, the molecular mechanisms underlying the effect of phosphorus on seed germination and post-germinated growth of oilseed rape are unclear so far. Here, we report the role of BnPHT1;4 in seed germination and early seedling development of Brassica napus.ResultsOur results show that BnPHT1;4 is preferentially expressed in cotyledons of early developing seedlings. Overexpression of BnPHT1;4 in oilseed rape promoted seed germination and seedling growth. Expression levels of the genes related to ABA and GA biosynthesis and signaling were significantly altered in BnPHT1;4 transgenic seedlings. Consequently, active GA level was up-regulated, whereas ABA content was down-regulated in BnPHT1;4 transgenic seedlings. Furthermore, exogenous GA could promote seed germination of wild type, while exogenous ABA could partially recover the advanced-germination phenotype of BnPHT1;4 transgenic seeds. Total phosphorus content in cotyledons of the transgenic seedlings was decreased more rapidly than that in wild type when Pi was supplied or deficient, and Pi contents in shoots and roots of the BnPHT1;4 transgenic plants were higher than those in wild type under high and low Pi conditions.ConclusionsOur data suggest that the high-affinity transporter BnPHT1;4 is involved in phosphorus acquisition and mobilization for facilitating seed germination and seedling growth of Brassica napus by modulating ABA and GA biosynthesis.

A CRISPR/Cas9 deletion into the phosphate transporter SlPHO1;1 reveals its role in phosphate nutrition of tomato seedlings.

In vascular (Arabidopsis thaliana) and non-vascular (Physcomitrella patens) plants, PHOSPHATE 1 (PHO1) homologs play important roles in the acquisition and transfer of phosphate. The tomato genome contains six genes (SlPHO1;1-SlPHO1;6) homologous to AtPHO1. The six proteins have typical characteristics of the plant PHO1 family, such as the three Syg1/Pho81/XPRI (SPX) subdomains in the N-terminal portion and one ERD1/XPR1/SYG1 (EXS) domain in the C-terminal portion. Phylogenetic analysis revealed that the SlPHO1 family is subdivided into three clusters. A pairwise comparison indicated that SlPHO1;1 showed the highest level of sequence identity/similarity (67.39/76.21%) to AtPHO1. SlPHO1;1 deletion mutants induced by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 displayed typical phenotypes of Pi starvation, such as decreased shoot fresh weight and increased root fresh weight, therefore having a greater root-to-shoot ratio. Mutants also accumulated more anthocyanin and had more soluble Pi content in the root and less in the shoot. These results indicate that SlPHO1;1 plays an important role in Pi transport in the tomato at seedling stage.

Phosphorus fractions in soil cultivated with vineyards after 62 years of poultry litter addition

Abstract: The objective of this work was to evaluate changes in phosphorus fractions in a Humic Cambisol cultivated with vineyards, after 62 years of additional fertilization with poultry litter. Soil samples were collected from two vineyards (V1 and V2) and a forested area adjacent to them. A total of 1,365 and 910 kg ha-1 P were applied to V1 and V2, respectively, throughout the past 62 years. Samples were collected at 0-10, 10-20, 20-30, and 30-40-cm soil depths for the analysis of soil physicochemical properties. The addition of poultry litter to the soil of the vineyards increased the contents of inorganic P (Pi) in all fractions, except in the residual fraction (residual-P), mainly at the 0-10-cm soil depth, in comparison with the forested area. The addition of poultry litter as fertilizer does not affect the organic P (Po) stock in the Humic Cambisol, it only increases the Pi contents of the soil.

Influence of Different Cowpea (&amp;lt;i&amp;gt;Vigna unguiculata&amp;lt;/i&amp;gt; (L.) Walp.) Genotypes from Burkina Faso on Proteases Inhibition

Cowpea is an important protein crop widespread in Africa. The purpose of this research was to determine the content of trypsin and chymotrypsin inhibitors in different genotypes of cowpea seeds. Trypsin percentage inhibition showed about 13.5-fold variation (5.12% ± 1.47 to 70.52% ± 6.58) between the cowpea genotypes respectively for KVx 421-2J and Kondesyoungo local. The chymotrypsin inhibitory activity varies among cowpea genotypes from 21.19 to 76.94%. The highest percent inhibitory activity was exhibited by KVx 396-4-5-2D on chymotrypsin. This study also showed significant correlations between type of cowpea genotype and trypsin inhibition potential and also between colour and chymotrypsin inhibition potential of cowpea seeds. Kondesyoungo local, a landraceae genotype exhibited the high potential to inhibit the trypsin enzyme. Coloured seeds of cowpea genotypes possess higher percentage inhibition of chymotrypsin than the colourless ones (p < 0.05). The calculated mean of trypsin and chymotrypsin inhibition activities showed that Labagela local genotype possess the highest inhibition activity of both protease enzymes. The PCA components analysis and the dendrogram performed basis on the protease inhibitory activities divided the thirty-one genotypes of cowpea used in this study into three classes. The results presented in this work can contribute greatly to the planning of a cowpea breeding program aimed at reducing the content of proteases inhibitors in order to improve the nutritional value of seeds or to increase PI content for tolerance to stored grain pests.

Identification of vacuolar phosphate efflux transporters in land plants.

Inorganic phosphate (Pi) is an essential component of all life forms. Land plants acquire Pi from the soil through roots and associated symbioses, and it is then transported throughout the plant. When sufficient, excess Pi is stored in vacuoles for remobilization following Pi deficiency. Although Pi release from the vacuoles to the cytoplasm serves as a critical mechanism for plants to adapt to low-Pi stress, the transporters responsible for vacuolar Pi efflux have not been identified. Here, we identified a pair of Oryza sativa vacuolar Pi efflux transporters (OsVPE1 and OsVPE2) that were more abundant in plants grown under Pi-deficient conditions. These OsVPE proteins can transport Pi into yeast cells and Xenopus laevis oocytes. Vacuolar Pi content was higher in the loss-of-function Osvpe1 Osvpe2 double mutant than in wild type, particularly under low-Pi stress. Overexpression of either OsVPE1 or OsVPE2 in transgenic plants reduced vacuolar Pi content, consistent with a role in vacuolar Pi efflux. We demonstrate that these VPE proteins evolved from an ancient plasma membrane glycerol-3-phosphate transporter protein. Together, these data indicate that this transporter was recruited to the vacuolar membrane to catalyse Pi efflux during the course of land plant evolution.

Vacuolar Phosphate Transporters Contribute to Systemic Phosphate Homeostasis Vital for Reproductive Development in Arabidopsis.

Vacuolar storage of phosphate (Pi) is essential for Pi homeostasis in plants. Recent studies have identified a family of vacuolar Pi transporters, VPTs (PHT5s), responsible for vacuolar sequestration of Pi. We report here that both VPT1 and VPT3 contribute to cytosol-to-vacuole Pi partitioning. Although VPT1 plays a predominant role, VPT3 is particularly important when VPT1 is absent. Our data suggested that the vpt1 vpt3 double mutant was more defective in Pi homeostasis than the vpt1 single mutant, as indicated by Pi accumulation capacity, vacuolar Pi influx, subcellular Pi allocation, and plant adaptability to changing Pi status. The remaining member of the VPT family, VPT2 (PHT5;2), did not appear to contribute to Pi homeostasis in such assays. Particularly interesting is the finding that the vpt1 vpt3 double mutant was impaired in reproductive development with shortened siliques and impaired seed set under sufficient Pi, and this phenotype was not found in the vpt1 vpt2 and vpt2 vpt3 double mutants. Measurements of Pi contents revealed Pi over-accumulation in the floral organs of vpt1 vpt3 as compared with the wild type. Further analysis identified excess Pi in the pistil as inhibitory to pollen tube growth, and thus seed yield, in the mutant plants. Reducing the Pi levels in culture medium or mutation of PHO1, a Pi transport protein responsible for root-shoot transport, restored the seed set of vpt1 vpt3 Thus, VPTs, through their function in vacuolar Pi sequestration, control the fine-tuning of systemic Pi allocation, which is particularly important for reproductive development.

Physiological status of high and low metabolism Hevea clones in the difference stage of tapping panel dryness

Abstract. Tristama R, Mawaddah PAS, Ade-Fipriani L, Junaidi. 2019. Physiological status of high and low metabolism Hevea clones in the difference stage of tapping panel dryness. Biodiversitas 20: 367-373. Tapping panel dryness (TPD) caused productivity of rubber trees drop sharply. However, the increase of TPD stage has not been completely elucidated, especially in physiological aspects. TPD incident was higher occurred in high metabolism than low metabolism clones. The incident has been classified based on visual observation. This research aimed to explore the physiological characters to identifying the physiological changes of each TPD stage in the two metabolism types of rubber clones, IRR 42 (low metabolism) and IRR 118 (high metabolism). The physiological parameters such as thiol, Pi content and peroxidase activity were specifically in each clone and the tissue types (bark or laticifer). The physiological pattern of IRR 42 was a difference with that of IRR 118 for the increase of the TPD stages. Phosphate inorganic content in the latex and bark were a decline in the TPD affected trees, whereas the sucrose content was relatively constant. The pattern of changes of thiol content in IRR 42 was reverse with IRR 118, both in the latex or bark tissue. Peroxidases activity in the latex and bark negatively correlated with the TPD stage. The decline of Pi and peroxidase activity can be used to identify the TPD incident in rubber trees.

A novel glycerophosphodiester phosphodiesterase improves phosphate deficiency tolerance in rice

Soil phosphate (Pi) deficiency is major constraint for rice cultivation worldwide. Cellular membranes account for one third of cellular organic phosphorus (P) in the form of phospholipids. Therefore, remobilization of Pi from membrane phospholipids under Pi deficiency can be an important strategy to improve phosphorus use efficiency. Glycerophosphodiester phosphodiesterases (GDPDs) hydrolyse intermediate product of phospholipid catabolism, glycerophosphodiesters to glycerol-3-phosphate, a precursor for P and non P-lipid biosynthesis. Here, we show that OsGDPD2 is a Pi deficiency responsive gene, which is transcriptionally regulated by OsPHR2. In silico analysis of active site residues and enzymatic assays confirmed phosphodiesterase activity of OsGDPD2. All overexpression lines showed higher GDPD activity, Pi content, root growth, and biomass accumulation as compared with wild type. Conversely, silencing of OsGDPD2 led to decreased GDPD activity and Pi content. Notably, most of the P-containing metabolites and fatty acids were elevated in transgenic lines. Further, quantitative analysis of polar lipids revealed higher accumulation of several classes of phospholipids and galactolipids in overexpression lines indicating a potential role of OsGDPD2 in de novo glycerolipid biosynthesis. Thus, present study provides insights into novel physiological roles of OsGDPD2 in low Pi acclimation in rice.