“Phosphate Metal Interactions Govern Root Development”

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Thursday 28 February 2019, 11:00 - 12:30

 
ABSTRACT

Inorganic phosphate (Pi) is a major node in bioenergetics and genuinely limiting nutrient of plant productivity. Responses to Pi deficiency reprioritize Pi allocation and maximize Pi acquisition by adjusting metabolism and root development. In search of Pi, root growth must negotiate abundant soil metals and their toxicities, (foremost Al and Fe), which severely restrict Pi bioavailability by forming insoluble mineral complexes. Work in Arabidopsis revealed antagonistic interactions between Pi and its associated metals in Pi sensing. We showed that two functionally interacting genes, PDR2 and LPR1, mediate Fe-dependent local Pi sensing. PDR2, the single orphan P5-type ATPase ATP5A, functions in the ER and controls cell wall-targeted LPR1 ferroxidase activity, which causes rapid (<20h) cell type-specific Fe accumulation upon Pi deprivation. Antagonistic Pi-Fe interactions in cell walls trigger ROS production and callose deposition in root tips, followed by inhibition of cell-to-cell communication and root meristem activity. Loss of PDR2 also alters pectin deposition, expression of cell wall modifying enzymes, and root exudation profiles, which support a function of PDR2 in secretory processes and cell wall remodeling. A pdr2 suppressor screen identified new lpr1 mutations and two additional genes, ALMT1 and STOP1, which interact to activate malate exudation into the rhizosphere and cell wall space upon Pi limitation. ALMT1 is a direct target gene of the STOP1 transcription factor and encodes an Al-activated malate efflux channel of key importance for Al detoxification, which points to intricate Pi-Al interactions in Pi sensing.

Location Jozef Schell Seminar Room
Contact Prof Steffen Abel
Leibniz Institute of Plant Biochemistry
Department of Molecular Signal Processing
Halle
GERMANY