A PINOID-Dependent Binary Switch in Apical-Basal PIN Polar Targeting Directs Auxin Efflux

Abstract

Polar transport-dependent local accumulation of auxin provides positional cues for multiple plant patterning processes. This directional auxin flow depends on the polar subcellular localization of the PIN auxin efflux regulators. Overexpression of the PINOID protein kinase induces a basal-to-apical shift in PIN localization, resulting in the loss of auxin gradients and strong defects in embryo and seedling roots. Conversely, pid loss of function induces an apical-to-basal shift in PIN1 polar targeting at the inflorescence apex, accompanied by defective organogenesis. Our results show that a PINOID-dependent binary switch controls PIN polarity and mediates changes in auxin flow to create local gradients for patterning processes.

Divide and conquer: development and cell cycle genes in plant transformation

“…We propose the use of genes involved in cell polarization and early meristem formation to overcome this type of limitation. Polar auxin transport generates gradients that underlie the tropic growth response, leading to apical-basal patterning [11]. PINOID (PID) is a serine-threonine kinase that regulates auxin transport and is the major determinant of PINFORMED (PIN) protein localization (i.e.…”

“…PINOID (PID) is a serine-threonine kinase that regulates auxin transport and is the major determinant of PINFORMED (PIN) protein localization (i.e. PIN1, PIN2 and PIN4) [11]. In shoot cells, where PID is normally expressed, PIN1 is located on the apical membranes, whereas in pid mutants, PIN1 is mistargetted to basal membranes [11]: constitutive expression of PID causes loss of meristem identity in the primary root.…”

“…PIN1, PIN2 and PIN4) [11]. In shoot cells, where PID is normally expressed, PIN1 is located on the apical membranes, whereas in pid mutants, PIN1 is mistargetted to basal membranes [11]: constitutive expression of PID causes loss of meristem identity in the primary root. PIN proteins focus and stabilize auxin effects in both proximo-distal and lateral dimensions.…”

“…The processes of plant transformation and regeneration from a transgenic cell can stall at several key points, including: (1) the acquisition of a stem-cell-like state in cells as they re-enter the cell cycle [7]; (2) progression between the G1 and S phases of the cycle [8,9] (Box 1); and (3) the differentiation of the transformed cell into a new embryo or meristem [10][11][12][13]. In this manuscript, we consider transformation to be the recovery of cells expressing a foreign gene for use as a selectable marker, and regeneration to be the organogenesis or embryogenesis from the genetically transformed cells.…”

Plant tropisms: providing the power of movement to a sessile organism

“…Recently it has been shown that TCH3 binds to PINOID (PID), a protein serine/ threonine kinase, in a yeast two-hybrid assay (Benjamins et al, 2003). PINOID had previously been shown to be necessary for proper auxin signaling (Bennet et al, 1996;Christensen et al, 2000) and a recent study suggests that it acts as a switch to regulate intracellular localization and the function of the PIN familu of auxin efflux regulators (Friml et al, 2004). TCH3 protein appears to bind PID and regulate the ability of the kinase to phosphorylate substrates in response to changing calcium ion levels (Benjamins et al, 2003).…”