Under phosphate starvation conditions, Fe and Al trigger accumulation of the transcription factor STOP1 in the nucleus of Arabidopsis root cells.

Abstract

Low-phosphate (Pi) conditions are known to repress primary root growth of Arabidopsis at low pH and in an Fe-dependent manner. This growth arrest requires accumulation of the transcription factor STOP1 in the nucleus, where it activates the transcription of the malate transporter gene ALMT1; exuded malate is suspected to interact with extracellular Fe to inhibit root growth. In addition, ALS3 - an ABC-like transporter identified for its role in tolerance to toxic Al - represses nuclear accumulation of STOP1 and the expression of ALMT1. Until now it was unclear whether Pi deficiency itself or Fe activates the accumulation of STOP1 in the nucleus. Here, by using different growth media to dissociate the effects of Fe from Pi deficiency itself, we demonstrate that Fe is sufficient to trigger the accumulation of STOP1 in the nucleus, which, in turn, activates the expression of ALMT1. We also show that a low pH is necessary to stimulate the Fe-dependent accumulation of nuclear STOP1. Furthermore, pharmacological experiments indicate that Fe inhibits proteasomal degradation of STOP1. We also show that Al acts like Fe for nuclear accumulation of STOP1 and ALMT1 expression, and that the overaccumulation of STOP1 in the nucleus of the als3 mutant grown in low-Pi conditions could be abolished by Fe deficiency. Altogether, our results indicate that, under low-Pi conditions, Fe2/3+ and Al3+ act similarly to increase the stability of STOP1 and its accumulation in the nucleus where it activates the expression of ALMT1.

• Authors: Christian Godon, Caroline Mercier, Xiaoyue Wang, Pascale David, Pierre Richaud, Laurent Nussaume, Dong Liu, Thierry Desnos
• Journal: The Plant journal : for cell and molecular biology (Plant J) Vol. 99 Issue 5 Pg. 937-949 (09 2019) ISSN: 1365-313X [Electronic] England
• PMID: 31034704 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2019 The Authors The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.

Chemical References

• ALMT1 protein, Arabidopsis
• ALS3 protein, Arabidopsis
• ATP-Binding Cassette Transporters
• Arabidopsis Proteins
• Cation Transport Proteins
• IRT1 protein, Arabidopsis
• Malates
• Organic Anion Transporters
• Phosphates
• STOP1 protein, Arabidopsis
• Transcription Factors
• malic acid
• Aluminum
• Iron

Topics

• ATP-Binding Cassette Transporters (metabolism)
• Aluminum (metabolism)
• Arabidopsis (genetics, growth & development, metabolism)
• Arabidopsis Proteins (metabolism)
• Cation Transport Proteins (genetics, metabolism)
• Cell Nucleus (metabolism)
• Gene Expression Regulation, Plant
• Iron (metabolism)
• Malates
• Organic Anion Transporters (metabolism)
• Phosphates (metabolism)
• Plant Roots (genetics, metabolism)
• Transcription Factors (genetics, metabolism)