NO AND ROS REGULATION OF FIT1 AND FRO2 EXPRESSION UNDER IRON DEFICIENCY IN A. thaliana ROOTS

D'AMBROSIO JM, FERNANDEZ MB, SOTO D, VICARIO R, LAXALT A, TEN HAVE A, PINEDO M, LAMATTINA L .

Villa Carloz Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2008

SAIB

Iron deficiency alters plant molecular physiology. Under these conditions, Arabidopsis thaliana have developed a strategy that implies rizophere acidifications, reduction of Fe+3 by Fe+3-reductasa FRO" and the uptake of Fe+2. The bHLH transcription factor FIT1, whose expression is regulated by nitric oxide (NO) under iron deficiency in tomato, regulates FRO2 mRNA levels. Preliminary evidence showed that iron deficiency increases NO and ROS levels. Crosstalk between ROS and NO has been extensively studied in many patho-phisiological processes. We decided to study NO and ROS effects under iron deficiency in A. thaliana roots. Treatments with H2O2 scavenger and catalase produced an increase in NO and a decrease in FRO2 and FIT1 transcript levels under iron deficiency. The NADPH oxidase (NOX) is a superoxide producing enzyme. In order to elucidate the enzymatic source of ROS under iron deficiency we inhibited NOX with apocynin. This treatment did not show any differences in mRNA levels of FRO2 and FIT1. However, it was observed an increase in NO levels under this conditions. Results indicated that scavenging of H2O2 and inhibition of NOX did not prevent the accumulation of NO produced under iron deficiency. However, the presence of H2O2 would be necessary for the full FRO2 and FIT1 induction under iron deficiency suggesting it acts in concert or downstream of NO in plant response to iron deprivation.