Cellular and Subcellular Phosphate Transport Machinery in Plants

Abstract

Phosphorus (P) is an essential element required for incorporation into several biomolecules and for various biological functions; it is, therefore, vital for optimal growth and development of plants. The extensive research on identifying the processes underlying the uptake, transport, and homeostasis of phosphate (Pi) in various plant organs yielded valuable information. The transport of Pi occurs from the soil into root epidermal cells, followed by loading into the root xylem vessels for distribution into other plant organs. Under conditions of Pi deficiency, Pi is also translocated from the shoot to the root via the phloem. Vacuoles act as a storage pool for extra Pi, enabling its delivery to the cytosol, a process which plays an important role in the homeostatic control of cytoplasmic Pi levels. In mitochondria and chloroplasts, Pi homeostasis regulates ATP synthase activity to maintain optimal ATP levels. Additionally, the endoplasmic reticulum functions to direct Pi transporters and Pi toward various locations. The intracellular membrane potential and pH in the subcellular organelles could also play an important role in the kinetics of Pi transport. The presented review provides an overview of Pi transport mechanisms in subcellular organelles, and also discusses how they affect Pi balancing at cellular, tissue, and whole-plant levels.

Selenite Uptake and Transformation in Rice Seedlings (Oryza sativa L.): Response to Phosphorus Nutrient Status

“…This phenomenon might be attributable to the competition between P and Se during plant transport, and as P is an important macronutrient for plants, it might be transported preferentially, especially under P-deficient condition. Previous studies have shown that OsPT6 likely mediates P translocation throughout the plants and is strongly up-regulated under P starvation (Luan et al, 2017;Srivastava et al, 2018). The transcript abundance of OsPT6 was notably elevated in the roots of an ltn1 mutant, which exhibited much higher rates of Se uptake than wide-type plants (Zhang et al, 2014).…”

“…In recent decades, numerous studies have investigated the subcellular distributions of various heavy metals (such as cadmium and lead) to reveal the tolerance and detoxification strategies of plants (Sha et al, 2019;Xiao et al, 2019;Yang et al, 2019). Other studies also focused on nutrient elements (Grillet et al, 2014;Srivastava et al, 2018) and rareearth elements (Shen et al, 2014). Nonetheless, a few studies have reported about the subcellular Se distribution and accumulation in plants.…”

Phosphate or nitrate imbalance induces stronger molecular responses than combined nutrient deprivation in roots and leaves of chickpea plants

“…Up‐regulated expression of these PHT1 genes might contribute to increased Pi uptake from the soil by the roots and improved root‐to‐shoot translocation of Pi in chickpea, as reported for Arabidopsis plants (Lapis‐Gaza, Jost, & Finnegan, 2014; Mudge, Rae, Diatloff, & Smith, 2002). With respect to leaves, three PHT1 genes ( PHT1;3 / XM_004495263.2 , PHT1;4 / XM_012713920.1 and PHT1;9 / XM_004505264.2 ) were up‐regulated in response to Pi deficiency (Table 1 and Figure S6), which might contribute to increased Pi remobilization from source leaves to sink leaves of –Pi/+NO 3 − plants (Chang et al, 2019; Srivastava et al, 2018). In addition, while the expression of genes belonging to the PHOSPHATE1 ( PHO1 ) family, which are implicated in the loading of Pi into the xylem and Pi translocation from roots to shoots (Srivastava et al, 2018), was not altered in the roots under Pi starvation, up‐regulation of the PHO1;H1 / XM_004509529.2 gene was observed in the leaves of –Pi/+NO 3 − versus +Pi/+NO 3 − plants (Table 1 and Figure S6).…”

Lateral Transport of Organic and Inorganic Solutes

“…Phosphorus (P) is a macronutrient essential for cellular processes such as energy production, redox reactions, photosynthesis, and phosphorylation/dephosphorylation reactions [146]. Phosphorus enters the plant root system in the form of inorganic P (Pi), such as PO 4 3− , H 2 PO 4 − , or HPO 4 2− , through an energized process involving H + /Pi co-transport in order to overcome the negative membrane potential [146].…”

“…Phosphorus (P) is a macronutrient essential for cellular processes such as energy production, redox reactions, photosynthesis, and phosphorylation/dephosphorylation reactions [146]. Phosphorus enters the plant root system in the form of inorganic P (Pi), such as PO 4 3− , H 2 PO 4 − , or HPO 4 2− , through an energized process involving H + /Pi co-transport in order to overcome the negative membrane potential [146]. Pi is then transported through the different root tissues through the action of, at least, the AtPHO1 and AtPHO1;H1 transporters, which are expressed in the endodermis and the pericycle, respectively, before being loaded into the xylem sap for root-to-shoot transport [102,103].…”