The Phosphate Transporter Gene OsPht1;4 Is Involved in Phosphate Homeostasis in Rice.
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ABSTRACT:
SUBMITTER: Ye Y
PROVIDER: S-EPMC4430236 | biostudies-literature | 2015
REPOSITORIES: biostudies-literature
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Project description:Inorganic phosphate (Pi) is stored in the vacuole, allowing plants to adapt to variable Pi availability in the soil. The transporters that mediate Pi sequestration into vacuole remain unknown, however. Here we report the functional characterization of Vacuolar Phosphate Transporter 1 (VPT1), an SPX domain protein that transports Pi into the vacuole in Arabidopsis. The vpt1 mutant plants were stunted and consistently retained less Pi than wild type plants, especially when grown in medium containing high levels of Pi. In seedlings, VPT1 was expressed primarily in younger tissues under normal conditions, but was strongly induced by high-Pi conditions in older tissues, suggesting that VPT1 functions in Pi storage in young tissues and in detoxification of high Pi in older tissues. As a result, disruption of VPT1 rendered plants hypersensitive to both low-Pi and high-Pi conditions, reducing the adaptability of plants to changing Pi availability. Patch-clamp analysis of isolated vacuoles showed that the Pi influx current was severely reduced in vpt1 compared with wild type plants. When ectopically expressed in Nicotiana benthamiana mesophyll cells, VPT1 mediates vacuolar influx of anions, including Pi, SO4(2-), NO3(-), Cl(-), and malate with Pi as that preferred anion. The VPT1-mediated Pi current amplitude was dependent on cytosolic phosphate concentration. Single-channel analysis showed that the open probability of VPT1 was increased with the increase in transtonoplast potential. We conclude that VPT1 is a transporter responsible for vacuolar Pi storage and is essential for Pi adaptation in Arabidopsis.
| S-EPMC4664319 | biostudies-literature
Project description:Myeloblastosis (MYB) transcription factors play central roles in plant developmental processes and in responses to nutrient deficiency. In this study, OsMYB5P, an R2R3-MYB transcription factor, was isolated and identified from rice (Oryza sativa L. 'Dongjin') under inorganic phosphate (Pi)-deficient conditions. OsMYB5P protein is localized to the nucleus and functions as a transcription activator in plant development. Overexpression of OsMYB5P in rice and Arabidopsis (Arabidopsis thaliana Col-0) increases tolerance to phosphate starvation, whereas OsMYB5P knock-out through RNA interference increases sensitivity to Pi depletion in rice. Furthermore, shoots and roots of transgenic rice plants overexpressing OsMYB5P were longer than those of wild plants under both normal and Pi-deficient conditions. These results indicate that OsMYB5P is associated with the regulation of shoot development and root- system architecture. Overexpression of OsMYB5P led to increased Pi accumulation in shoots and roots. Interestingly, OsMYB5P directly bound to MBS (MYB binding site) motifs on the OsPT5 promoter and induced transcription of OsPT5 in rice. In addition, overexpression of OsMYB5P in Arabidopsis triggered increased expression of AtPht1;3, an Arabidopsis Pi transporter, in shoots and roots under normal and Pi-deficient conditions. Together, these results demonstrate that overexpression of OsMYB5P increases tolerance to Pi deficiency in plants by modulating Pi transporters at the transcriptional level in monocots and dicots.
| S-EPMC5864048 | biostudies-literature
Project description:In eukaryotic cells, phosphorus is assimilated and utilized primarily as phosphate (Pi). Pi homeostasis is mediated by transporters that have not yet been adequately characterized in green algae. This study reports on PHOSPHATE TRANSPORTER 4-7 (CrPHT4-7) from Chlamydomonas reinhardtii, a member of the PHT4 transporter family, which exhibits remarkable similarity to AtPHT4;4 from Arabidopsis (Arabidopsis thaliana), a chloroplastic ascorbate transporter. Using fluorescent protein tagging, we show that CrPHT4-7 resides in the chloroplast envelope membrane. Crpht4-7 mutants, generated by the CRISPR/Cas12a-mediated single-strand templated repair, show retarded growth, especially in high light, reduced ATP level, strong ascorbate accumulation, and diminished non-photochemical quenching in high light. On the other hand, total cellular phosphorous content was unaffected, and the phenotype of the Crpht4-7 mutants could not be alleviated by ample Pi supply. CrPHT4-7-overexpressing lines exhibit enhanced biomass accumulation under high light conditions in comparison with the wild-type strain. Expressing CrPHT4-7 in a yeast (Saccharomyces cerevisiae) strain lacking Pi transporters substantially recovered its slow growth phenotype, demonstrating that CrPHT4-7 transports Pi. Even though CrPHT4-7 shows a high degree of similarity to AtPHT4;4, it does not display any substantial ascorbate transport activity in yeast or intact algal cells. Thus, the results demonstrate that CrPHT4-7 functions as a chloroplastic Pi transporter essential for maintaining Pi homeostasis and photosynthesis in C. reinhardtii.
| S-EPMC10904345 | biostudies-literature
Project description:Brassinosteroids (BRs) are steroid hormones that modulate numerous physiological processes in plants. However, few studies have focused on the involvement of BRs in sensing and responding to the stress of mineral nutrient deficiency. In the present study, we evaluated the roles of BRs in the response of rice (Oryza sativa) to iron (Fe) deficiency during Fe uptake, transport, and translocation. Exogenous application of 24-epibrassinolide (EBR) to wild-type (WT) plants exaggerated leaf symptoms of Fe deficiency and suppressed growth. EBR increased and decreased Fe concentrations in roots and shoots, respectively, under both Fe-deficient and Fe-sufficient conditions. Transcripts involved in Fe homeostasis, including OsIRT1, OsYSL15, OsYSL2, OsNAS1, and OsNAS2, were enhanced by EBR under Fe-deficient conditions. EBR depressed expression of OsNAS1, OsNAS2, and OsYSL2 in shoots, and inhibited Fe transport and translocation via the phloem. Rice mutant d2-1, which is defective in BR biosynthesis, was more tolerant to Fe deficiency than the WT, and accumulated greater amounts of Fe in roots than the WT under Fe-sufficient conditions. A greater upregulation of OsIRT1, OsYSL15, OsYSL2, OsNAS1, and OsNAS2 in the d2-1 mutant compared to the WT was found under Fe-sufficient conditions, while expression of these genes in the d2-1 mutant was lower than in the WT under Fe-deficient conditions. The greater tolerance of the d2-1 mutant could be partly mitigated by exogenous application of EBR. These novel findings highlight the important role of BR in mediating the response of strategy II plants to Fe deficiency by regulating Fe uptake and translocation in rice.
| S-EPMC4986876 | biostudies-other
Project description:The absorption of nutrients and disease resistance are two indispensable physiological processes in plants; however, it is still largely unknown whether there is cross-talk between their molecular signaling pathways. In this study, we identified the rice OsPT8 protein, which is a member of the phosphate transporters (PTs) Pht1 family and also plays a role in rice disease resistance. The transcriptional level of OsPT8 is suppressed after infection with rice pathogens and treatment with pathogen-associated molecular patterns (PAMPs). Overexpression of OsPT8 suppresses rice disease resistance against the pathogens Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae. Accordingly, the transcription level of resistance related genes, such as PAL and PBZ1, is inhibited in plants overexpressing OsPT8 (OsPT8-OX) after inoculation with these pathogens. In OsPT8-OX plants, PAMPs-triggered immunity (PTI) response genes, such as OsRac1 and SGT1, are suppressed during treatment with PAMPs chitin or flg22. Moreover, the typical response of PTI is suppressed after chitin or flg22 treatment. We also identified OsPT8 as an interactor of a rice mitogen-activated protein kinase BWMK1, which is a regulator of disease resistance. Under low phosphate (Pi) conditions, the OsPT8-OX plants display better agronomic traits than the control plants. However, the differences in development between OsPT8-OX and the control plants are reduced upon the increase of Pi concentration. These results demonstrate that OsPT8 regulates the transduction of Pi signaling for development and negatively regulates rice immunity.
| S-EPMC6443681 | biostudies-literature
Project description:Cadmium (Cd) is a heavy metal toxic to humans and the accumulation of Cd in the rice grain is a major agricultural problem, particularly in Asia. The role of the iron transporter OsNRAMP1 in Cd uptake and transport in rice was investigated here. An OsNRAMP1:GFP fusion protein was localized to the plasma membrane in onion epidermal cells. The growth of yeast expressing OsNRAMP1 was impaired in the presence of Cd compared with yeast transformed with an empty vector. Moreover, the Cd content of OsNRAMP1-expressing yeast exceeded that of the vector control. The expression of OsNRAMP1 in the roots was higher in a high Cd-accumulating cultivar (Habataki) than a low Cd-accumulating cultivar (Sasanishiki) regardless of the presence of Cd, and the amino acid sequence of OsNRAMP1 showed 100% identity between Sasanishiki and Habataki. Over-expression of OsNRAMP1 in rice increased Cd accumulation in the leaves. These results suggest that OsNRAMP1 participates in cellular Cd uptake and Cd transport within plants, and the higher expression of OsNRAMP1 in the roots could lead to an increase in Cd accumulation in the shoots. Our results indicated that OsNRAMP1 is an important protein in high-level Cd accumulation in rice.
| S-EPMC3192999 | biostudies-literature
Project description:OsSIZ1, a small ubiquitin-related modifier (SUMO) E3 ligase, exerts regulatory influences on the developmental responses and phosphate (Pi) homeostasis in rice (Oryza sativa). Whether paralogs OsSIZ1 and OsSIZ2 are functionally redundant or the latter regulates these traits independent of the former is not known. To determine this, in this study, OsSIZ2 was functionally characterized by employing reverse genetic approaches. Although the relative expression of OsSIZ2 was spatiotemporally regulated, it showed constitutive expression in root and leaf blade irrespective of Pi regime. Analysis of T-DNA insertion knockout (ossiz2) and RNAi-mediated knockdown (Ri1-3) mutants revealed positive influences on growth and developmental responses including yield-related traits. On the contrary, these mutants exhibited negative effects on the concentrations of Pi and total P in different tissues. The relative expression levels of some of the genes that are involved in Pi sensing and signaling cascades were differentially modulated in the mutants. Further, attenuation in the expression levels of OsSIZ2 in the roots of ossiz1 and relatively similar trend of the effects of the mutation in OsSIZ1 and OsSIZ2 on growth and development and total P concentration in different tissues suggested a prevalence of partial functional redundancy between these paralogs.
| S-EPMC5612973 | biostudies-literature
Project description:Iron is an essential metal element for all living organisms. Graminaceous plants produce and secrete mugineic acid family phytosiderophores from their roots to acquire iron in the soil. Phytosiderophores chelate and solubilize insoluble iron hydroxide in the soil. Subsequently, plants take up iron-phytosiderophore complexes through specific transporters on the root cell membrane. Phytosiderophores are also thought to be important for the internal transport of various transition metals, including iron. In this study, we analyzed TOM2 and TOM3, rice homologs of transporter of mugineic acid family phytosiderophores 1 (TOM1), a crucial efflux transporter directly involved in phytosiderophore secretion into the soil. Transgenic rice analysis using promoter-?-glucuronidase revealed that TOM2 was expressed in tissues involved in metal translocation, whereas TOM3 was expressed only in restricted parts of the plant. Strong TOM2 expression was observed in developing tissues during seed maturation and germination, whereas TOM3 expression was weak during seed maturation. Transgenic rice in which TOM2 expression was repressed by RNA interference showed growth defects compared with non-transformants and TOM3-repressed rice. Xenopus laevis oocytes expressing TOM2 released (14)C-labeled deoxymugineic acid, the initial phytosiderophore compound in the biosynthetic pathway in rice. In onion epidermal and rice root cells, the TOM2-GFP fusion protein localized to the cell membrane, indicating that the TOM2 protein is a transporter for phytosiderophore efflux to the cell exterior. Our results indicate that TOM2 is involved in the internal transport of deoxymugineic acid, which is required for normal plant growth.
| S-EPMC4646018 | biostudies-literature
Project description:Prior to the release of their cargoes into the vacuolar lumen, sorting endosomes mature into multivesicular bodies (MVB) through the action of ENDOSOMAL COMPLEX REQUIRED FOR TRANSPORT (ESCRT) protein complexes. MVB-mediated sorting of high affinity phosphate transporters (PHT1) to the vacuole limits their plasma membrane levels under phosphate sufficient conditions, a process that allows plants to maintain phosphate homeostasis. We describe here AtALIX, a cytosolic protein that associates to MVB by interacting with ESCRT-III subunit SNF7 and enables PHT1;1 trafficking to the vacuole. Thus, we show that the partial loss of function mutant Atalix-1 displays reduced vacuolar degradation of PHT1;1. AtALIX versions containing the Atalix-1 mutation showed reduced interaction with SNF7, providing a simple molecular explanation for impaired cargo trafficking in Atalix-1 mutants. Indeed, Atalix-1 mutation also hampered vacuolar sorting of brassinosteroid receptor BRI1. In line with a presumed broad target spectrum, Atalix-1 mutation is pleiotropic, provoking reduced plant growth, late flowering and altered vacuole morphogenesis, whereas null mutants are lethal, indicating that AtALIX controls diverse processes in plants being essential for their life.
2015-09-09 | PXD002075 | Pride
Project description:Natural resistance-associated macrophage proteins (NRAMPs) have been shown to transport a wide range of divalent metal ions, such as manganese (Mn), cadmium (Cd), and Iron (Fe). Iron is an essential micronutrient for plants and Fe deficiency can lead to chlorosis or decreased biomass. AtNRAMP6 has demonstrated the capability to transport Cd, but its physiological function is currently unclear. This study demonstrates that AtNRAMP6 is localized to the Golgi/trans-Golgi network and plays an important role in intracellular Fe homeostasis in the flowering plant genus Arabidopsis. GUS tissue-specific expression revealed that AtNRAMP6 is highly expressed in the lateral roots and young leaves (three to four top leaves) of Arabidopsis. Moreover, knocking out AtNRAMP6 was shown to impair lateral root growth without having a differential effect on the main root under Fe-deficient conditions. Lastly, the expression of AtNRAMP6 was found to exacerbate the sensitivity of the yeast mutant Δccc1 to an excessive amount of Fe. These findings indicate that AtNRAMP6 plays an important role in the growth of Arabidopsis in Fe-deficient conditions.
| S-EPMC6757856 | biostudies-literature