Abstract Low phosphorus (P) stress leads to a significant decrease in phosphate (Pi) content in rice, but there is a lack of systematic reviews of regulatory mechanisms of phosphate (Pi)-starvation rescue (PiSR) in rice. Herein, the low-Pi sensitive rice (Oriza sativa L.) cultivar Tongjing 981 was used as the material to clarify the mechanisms of gene expression regulation under low-Pi conditions in the Pi-starvation rescue system of rice. The results showed that low Pi induced the expression of phosphorus transporter (PHT) genes, including PHT1-1, PHT1-3, PHT1-4, PHT1-5, PHT1-6, PHT1-7, PHT1-8, PHT1-9, PHT1-10, PHO1, PHO3, and G3Pp1, promoting Pi absorption and transportation. Low Pi also induced the expression of the PHR3, SPX1, SPX2, SPX3, SPX5, and SPX6 genes, in turn regulating Pi starvation signals and maintaining Pi homeostasis. Moreover, low Pi induced the expressions of purple acid phosphatase (PAP)-encoding genes, including PAP2, PAP3, PAP15, PAP23, IPAP1, IPAP2, IPAP16, and NPP, that promote the conversion of soil-bound organic Pi into its inorganic form. Under low Pi conditions, the expression of the inorganic pyrophosphatase (PPA) genes (PPA1, PPA2, and PPA4) were induced, promoting the hydrolysis of pyrophosphate to inorganic monophosphate. Additionally, these conditions induced the expression of the pma1 gene, thus enhancing H+ secretion, which subsequently led to rhizosphere acidification. Induction of the PAPs, PPAs, and pma1 gene expressions promoted the activation of organic and inorganic Pi. Furthermore, low Pi induced the expressions of phospholipid hydrolysis- and glycolipid synthesis-related genes, including RNLE, PAH1, PAH2, DGD2, PLDZETA1, SQD2, NPC1, NPC4, LCAT3, and PLA2-II, which promote the biosynthesis of glycolipids and galactolipids and, in turn functionally compensated for phospholipid deficiency. The expression of PLP2 was also induced under low Pi stress, promoting membrane repair and the removal of oxidized lipids. Together, these results showed that low Pi could activate the PiSR system in plants by inducing the expression of the genes involved in Pi absorption and transportation, Pi homeostasis maintenance, Pi activation, and lipid membrane remodeling, thus improving the adaptability of rice to low Pi stress.

Study of the Regulatory Mechanisms of Phosphorus Homeostasis and Phosphate (Pi)-Starvation Rescue in Rice

期刊论文
发表日期：

2025年4月1日

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Y. Ding,
B. She,
X. Hu,
Y. Xing,
Z. Wang,
C. Ge,
E. Nie

摘要

Abstract

Low phosphorus (P) stress leads to a significant decrease in phosphate (Pi) content in rice, but there is a lack of systematic reviews of regulatory mechanisms of phosphate (Pi)-starvation rescue (PiSR) in rice. Herein, the low-Pi sensitive rice (Oriza sativa L.) cultivar Tongjing 981 was used as the material to clarify the mechanisms of gene expression regulation under low-Pi conditions in the Pi-starvation rescue system of rice. The results showed that low Pi induced the expression of phosphorus transporter (PHT) genes, including PHT1-1, PHT1-3, PHT1-4, PHT1-5, PHT1-6, PHT1-7, PHT1-8, PHT1-9, PHT1-10, PHO1, PHO3, and G3Pp1, promoting Pi absorption and transportation. Low Pi also induced the expression of the PHR3, SPX1, SPX2, SPX3, SPX5, and SPX6 genes, in turn regulating Pi starvation signals and maintaining Pi homeostasis. Moreover, low Pi induced the expressions of purple acid phosphatase (PAP)-encoding genes, including PAP2, PAP3, PAP15, PAP23, IPAP1, IPAP2, IPAP16, and NPP, that promote the conversion of soil-bound organic Pi into its inorganic form. Under low Pi conditions, the expression of the inorganic pyrophosphatase (PPA) genes (PPA1, PPA2, and PPA4) were induced, promoting the hydrolysis of pyrophosphate to inorganic monophosphate. Additionally, these conditions induced the expression of the pma1 gene, thus enhancing H⁺ secretion, which subsequently led to rhizosphere acidification. Induction of the PAPs, PPAs, and pma1 gene expressions promoted the activation of organic and inorganic Pi. Furthermore, low Pi induced the expressions of phospholipid hydrolysis- and glycolipid synthesis-related genes, including RNLE, PAH1, PAH2, DGD2, PLDZETA1, SQD2, NPC1, NPC4, LCAT3, and PLA2-II, which promote the biosynthesis of glycolipids and galactolipids and, in turn functionally compensated for phospholipid deficiency. The expression of PLP2 was also induced under low Pi stress, promoting membrane repair and the removal of oxidized lipids. Together, these results showed that low Pi could activate the PiSR system in plants by inducing the expression of the genes involved in Pi absorption and transportation, Pi homeostasis maintenance, Pi activation, and lipid membrane remodeling, thus improving the adaptability of rice to low Pi stress.