Regulation of Phosphate Starvation Responses in Plants: Signaling Players and Cross-Talks

Abstract

Phosphate (Pi) availability is a major factor limiting growth, development, and productivity of plants. In both ecological and agricultural contexts, plants often grow in soils with low soluble phosphate content. Plants respond to this situation by a series of developmental and metabolic adaptations that are aimed at increasing the acquisition of this vital nutrient from the soil, as well as to sustain plant growth and survival. The development of a comprehensive understanding of how plants sense phosphate deficiency and coordinate the responses via signaling pathways has become of major interest, and a number of signaling players and networks have begun to surface for the regulation of the phosphate-deficiency response. In practice, application of such knowledge to improve plant Pi nutrition is hindered by complex cross-talks, which are emerging in the face of new data, such as the coordination of the phosphate-deficiency signaling networks with those involved with hormones, photo-assimilates (sugar), as well as with the homeostasis of other ions, such as iron. In this review, we focus on these cross-talks and on recent progress in discovering new signaling players involved in the Pi-starvation responses, such as proteins having SPX domains.

The Phosphate Fast-Responsive Genes PECP1 and PPsPase1 Affect Phosphocholine and Phosphoethanolamine Content

“…Indeed, in Arabidopsis, the in vivo role of these overexpressors seems more directly linked to the degradation of PCho and PEth polar heads, the by-products of phospholipid degradation triggered in response to Pi starvation. We have demonstrated that their induction is largely under the control of PHR1/PHL1, adding them to the list of proteins involved in lipid metabolism under the control of these transcription factors (Rouached et al, 2010;Pant et al, 2015).…”

“…Specifically, tomato plants overexpressing LePS2;1 (homologous to PPsPase1 and PECP1) were reported to display altered Pi content, increased anthocyanin production, and enhanced acid phosphatase activity under Pi-rich conditions (Baldwin et al, 2008). To verify this hypothesis, we quantified the induction of several robust markers of Pi starvation responses (Duan et al, 2008;Rouached et al, 2010;Thibaud et al, 2010), including known players involved in Pi uptake and lipid remobilization (PHT1;4, SPX1, MGD2, MGD3, SQD1, and SQD2), and compared them to the expression level in their respective controls (wild type, low or high Pi). The triple KO mutants ( Fig.…”

“…Indeed, in Arabidopsis, the in vivo role of these overexpressors seems more directly linked to the degradation of PCho and PEth polar heads, the by-products of phospholipid degradation triggered in response to Pi starvation. We have demonstrated that their induction is largely under the control of PHR1/PHL1, adding them to the list of proteins involved in lipid metabolism under the control of these transcription factors (Rouached et al, 2010;Pant et al, 2015).The superfamily of HAD phosphatases is a very large and divergent group of enzymes, with very little overall homology but great diversity in substrates (Burroughs et al, 2006). These phosphatases are subdivided into different classes based on the overall structural arrangement of their active core (Burroughs et al, 2006).…”

Lipid Biosynthesis and Protein Concentration Respond Uniquely to Phosphate Supply during Leaf Development in Highly Phosphorus-Efficient Hakea prostrata

“…H. prostrata is restricted to low-P environments. It is thus likely that the P-starvation response that is well documented in other plants would never be triggered under natural low-P conditions in H. prostrata and that regulatory components found in plants such as Arabidopsis and rice (Oryza sativa; Rouached et al, 2010;Lin et al, 2014) have been attenuated or lost. This possibility is supported by the absence of orthologs in the H. prostrata transcriptome database for many lipid genes that are induced by the myeloblastosis transcription factor PHOS-PHATE STARVATION RESPONSE1 in response to Pi limitation in Arabidopsis (Bustos et al, 2010;AcevedoHernández et al, 2012).…”

Phosphorus Transport in Arabidopsis and Wheat: Emerging Strategies to Improve P Pool in Seeds

“…Achieving this objective necessitates a better understanding of how crops regulate P homeostasis. During the last decades, our knowledge on the molecular regulation of P transport and P redistribution in different plant organs during vegetative phase has progressed mainly in model plants such as Arabidopsis thaliana (for review, [17]). However, limited progress was achieved in crops such as wheat, a major dietary source of calories and protein for humans.…”