Arabidopsis TIR1/AFB auxin receptor family is involved in the adaptative response to abiotic stress.

IGLESIAS, MARÍA JOSÉ; TERRILE, MARÍA CECILIA; DI MAURO, MARÍA FLORENCIA; CASALONGUÉ, CLAUDIA

Carlos Paz, Cordoba, Argentina

Congreso; XLIV Reunión Anual SAIB; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Recently, auxin regulation has been involved in plant-pathogen interactions. However, the role of auxin signaling pathway during abiotic stress remains unclear. The aim of this work was to evaluate auxin receptors (TIR1, AFB1, AFB2 and AFB3) participation in the adaptative response of Arabidopsis thaliana plants against abiotic stress conditions. Double mutant plants tir1/afb1, tir1/afb2 and tir1/afb3 were analysed under oxidative stress caused by methyl-viologen (MV), hydrogen peroxide (H2O2) and salt stress. Thus, tir1/afb2 and tir1/afb3 double mutant seedlings growing in 10 nM MV presented 20 % less inhibition of root growth compared to WT plants, while tir1/afb1 showed similar response than WT plants. Quantification of cell death symptoms indicated that tir1/afb2 and tir1/afb3 mutant seedlings were also more resistant against oxidative treatments mediated by 20 mM H2O2. Superoxide ion (O2–) production in leaves, after 50 uM MV treatment, showed a reduce O2– production in tir1/afb2 mutant compared to WT. Moreover, tir1/afb2 double mutants exhibited reduce sensitivity against salt treatments during germination and root growth. These results allowed us to propose that A. thaliana plants repress auxin signaling as part of the response to abiotic stress as an adaptative strategy to modulate growth and stress tolerance.