Environmental Control of Phosphorus Acquisition: A Piece of the Molecular Framework Underlying Nutritional Homeostasis

Abstract

Homeostasis of phosphorus (P), an essential macronutrient, is vital for plant growth under diverse environmental conditions. Although plants acquire P from the soil as inorganic phosphate (Pi), its availability is generally limited. Therefore, plants employ mechanisms involving various Pi transporters that facilitate efficient Pi uptake against a steep concentration gradient across the plant–soil interface. Among the different types of Pi transporters in plants, some members of the PHOSPHATE TRANSPORTER 1 (PHT1) family, present in the plasma membrane of root epidermal cells and root hairs, are chiefly responsible for Pi uptake from the rhizosphere. Therefore, accurate regulation of PHT1 expression is crucial for the maintenance of P homeostasis. Previous investigations positioned the Pi-dependent post-translational regulation of PHOSPHATE STARVATION RESPONSE 1 (PHR1) transcription factor activity at the center of the regulatory mechanism controlling PHT1 expression and P homeostasis; however, recent studies indicate that several other factors also regulate the expression of PHT1 to modulate P acquisition and sustain P homeostasis against environmental fluctuations. Together with PHR1, several transcription factors that mediate the availability of other nutrients (such as nitrogen and zinc), light, and stress signals form an intricate transcriptional network to maintain P homeostasis under highly diverse environments. In this review, we summarize this intricate transcriptional network for the maintenance of P homeostasis under different environmental conditions, with a main focus on the mechanisms identified in Arabidopsis.

Arabidopsis Restricts Sugar Loss to a Colonizing Trichoderma harzianum Strain by Downregulating SWEET11 and -12 and Upregulation of SUC1 and SWEET2 in the Roots

“…This suggests that the fungus reduces the Pi starvation response during the early colonization phase, whereas the beneficial effect of the fungus is lost after 96 h. A possible explanation could be that the fungus initially provides Pi to the roots, either by direct transport from the fungal to the plant cell, or from the residual external soluble Pi. The mRNA level for PHR1 increases only marginally under Pi stress and root colonization (Figure 5), even though the transcription factor is considered as a central regulator controlling PHT1 expression and Pi homeostasis in Arabidopsis ( [27] and refs. therein).…”

A crucial role for a node‐localized transporter, HvSPDT, in loading phosphorus into barley grains

“…60–85% of total plant P) is finally allocated to grains, where P is mainly present in the form of phytic acid (PA) (Raboy, 2001; Dissanayaka et al ., 2018). In the last two decades, numerous studies have been conducted on the molecular mechanisms of P uptake and translocation in different plant species and great progress has been made towards the identification of P transporters and their regulation (Chiou & Lin, 2011; Jia et al ., 2021; Ueda et al ., 2021; Y. Wang et al ., 2021; Z. R. Wang et al ., 2021; Paz‐Ares et al ., 2022). By contrast, very few studies have addressed the molecular mechanisms underlying loading of P to grains, although grains are the major sink of P (Wang et al ., 2016).…”

The transcription factor OsWRKY10 inhibits phosphate uptake via suppressingOsPHT1;2expression under phosphate-replete conditions in rice

“…To cope with the scarcity of Pi in soil, plants have evolved a suite of delicate systems for the sensing, uptake, distribution, and metabolism of Pi ( Gu et al ., 2016 ; Huang et al ., 2020 ; Y. Wang et al , 2021 ). During the past two decades, dozens of regulators have been reported to be involved in Pi starvation signaling ( Ueda et al ., 2021 ; Z.R. Wang et al , 2021 ; Lambers, 2022 ; Paz-Ares et al ., 2022 ), among which a subclade of Myeloblastosis (MYB) transcription factors (TFs) termed PHOSPHATE STARVATION RESPONSE (PHR) have been demonstrated to be the central regulators activating the transcription of ~50% of Pi starvation-induced (PSI) genes ( Bustos et al ., 2010 ; Guo et al ., 2015 ).…”