Cytokinin and Nitrate signaling pathways induce primary root growth in Arabidopsis thaliana.

NAULIN P; TAMAYO KP; GRAS DE; VEGA A; GUTIÉRREZ RG

Puerto Varas

Simposio; Cytokinin and Nitrate signaling pathways induce primary root growth in Arabidopsis thaliana.; 2013

Nitrate can act as a potent signal to control growth and development in plants. However, the mechanisms by which nitrate exert its signaling role to control developmental processes are still poorly understood. We show that nitrate stimulates primary root growth mainly by stimulating meristem activity via cytokinin signaling. Citokinin perception and biosynthesis mutants exhibited shorter roots when grown with nitrate as the only nitrogen source. Histological analysis of the root tip revealed decreased cell division and elongation in the ahk2/ahk4 double mutants as compared to wild-type plants under nitrate regime. Cytokinin perception mutants and wild-type plants grown under nitrate conditions are indistinguishable at day 4 both at the molecular and histological level. However, 10 days after germination there is no detectable meristem activity in the ahk2/ahk4 double mutant and global analysis of gene expression revealed large changes in gene expression in the ahk2/ahk4 double mutant as compared to wild-type plants. Transcriptomics analysis identified important core cell cycle genes that may explain the observed phenotypes. Our results provide strong evidence linking nitrate and cytokinin signaling for the control of active cell division and elongation in the root tip under nitrate conditions.