Control of plant organ size by KLUH/CYP78A5-dependent intercellular signaling.
Plant organs grow to characteristic sizes that are genetically controlled. In animals, signaling by mobile growth factors is thought to be an effective mechanism for measuring primordium size, yet how plants gauge organ size is unclear. Here, we identify the Arabidopsis cytochrome P450 KLUH (KLU)/CYP78A5 as a stimulator of plant organ growth. While klu loss-of-function mutants form smaller organs because of a premature arrest of cell proliferation, KLU overexpression leads to larger organs with more cells. KLU promotes organ growth in a non-cell-autonomous manner, yet it does not appear to modulate the levels of known phytohormones. We therefore propose that KLU is involved in generating a mobile growth signal distinct from the classical phytohormones. The expression dynamics of KLU suggest a model of how the arrest of cell proliferation is coupled to the attainment of a certain primordium size, implying a common principle of size measurement in plants and animals.
Institut für Biologie III, Universität Freiburg, Schänzlestrasse 1, D-79104 Freiburg, Germany.
Elena
E
Anastasiou
Sabine
S
Kenz
Moritz
M
Gerstung
Daniel
D
MacLean
Jens
J
Timmer
Christian
C
Fleck
Michael
M
Lenhard
D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000502:physiology*; D049109:Cell Proliferation; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D009929:Organ Size; D010641:Phenotype; D035261:Plant Components, Aerial / Q000254:growth & development*; D011401:Promoter Regions, Genetic; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D003577:Cytochrome P-450 Enzyme System