Auxin and miRNA393: Towards a better understanding on mechanisms of developmental plasticity

CASALONGUÉ CLAUDIA A; IGELSIAS MJ; CASALONGUE, CA

Mar del Plata

Simposio; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación en Bioquímica

Auxin and miRNA393: Towards a better understanding on mechanisms of developmental plasticity Iglesias María J. and Casalongué, Claudia A.Instituto de Investigaciones Biológicas (IIB) UE-CONICET-Universidad Nacional de Mar del PlataOne of the most striking traits of plant plasticity is the modulation of development in response to environmental changes. The aim of this project is to contribute towards a better understanding on mechanisms that modulate developmental plasticity to abiotic stress. The phytohormone auxin regulates most of the key processes in plant development. Auxin activates gene expression through direct physical interaction with TIR1/AFB F-box receptor proteins. Phenotypic characterization of tir1/afb2 double mutants resulted in enhanced tolerance to oxidative and salt stresses. Further, we demonstrated that induction of miR393 is required for down regulation of auxin signaling and auxin-mediated physiological responses during salinity. Under stress mir393ab mutant unable to down-regulate TIR1-dependent signaling showed reduced inhibition of emergent and mature lateral roots number. Additionally, mir393ab mutant plants showed higher level of ROS in and reduced ascorbate peroxidase activity compared with wild-type plants. Likely, miR393 could be a critical checkpoint between auxin signaling and redox-associated components in order to coordinate tissue and time-specific growth responses. We also conclude that miR393-mediated down regulation of auxin signaling represents a gateway of stress signals into the development programme under stress conditions.