Spatiotemporal regulation of lateral root organogenesis in Arabidopsis by cytokinin.
The architecture of a plant's root system, established postembryonically, results from both coordinated root growth and lateral root branching. The plant hormones auxin and cytokinin are central endogenous signaling molecules that regulate lateral root organogenesis positively and negatively, respectively. Tight control and mutual balance of their antagonistic activities are particularly important during the early phases of lateral root organogenesis to ensure continuous lateral root initiation (LRI) and proper development of lateral root primordia (LRP). Here, we show that the early phases of lateral root organogenesis, including priming and initiation, take place in root zones with a repressed cytokinin response. Accordingly, ectopic overproduction of cytokinin in the root basal meristem most efficiently inhibits LRI. Enhanced cytokinin responses in pericycle cells between existing LRP might restrict LRI near existing LRP and, when compromised, ectopic LRI occurs. Furthermore, our results demonstrate that young LRP are more sensitive to perturbations in the cytokinin activity than are developmentally more advanced primordia. We hypothesize that the effect of cytokinin on the development of primordia possibly depends on the robustness and stability of the auxin gradient.
Department of Plant Systems Biology, Flanders Institute for Biotechnology, 9052 Ghent, Belgium.
Agnieszka
A
Bielach
Katerina
K
Podlesáková
Peter
P
Marhavy
Jérôme
J
Duclercq
Candela
C
Cuesta
Bruno
B
Müller
Wim
W
Grunewald
Petr
P
Tarkowski
Eva
E
Benková
D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D003583:Cytokinins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D018519:Meristem / Q000254:growth & development; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
C117138:ARR1 protein, Arabidopsis; C473997:ARR11 protein, Arabidopsis; D029681:Arabidopsis Proteins; D003583:Cytokinins; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D014157:Transcription Factors; D019883:Alkyl and Aryl Transferases; C024274:adenylate isopentenyltransferase