NO and ROS- mediated regulation of FIT1 and FRO2 expression under iron deficiency in A. thaliana roots

DAMBROSIO, JM; FERNÁNDEZ, MB; SOTO, |D; VICARIO, R; LAXALT, A; TEN HAVE, A; PINEDO, M; LAMATTINA, L

Carlos paz, Provincia de Córdoba, Argentina

Congreso; XLIV Reunión Anual SAIB; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Iron deficiency alters plant molecular physiology. Under these conditions, Arabidopsis thaliana have developed a strategy that implies rizosphere acidification, reduction of Fe3+ by  the Fe3+-reductase FRO2 and the uptake of Fe2+. The bHLH transcription factor FIT1, whose expression is regulated by nitric oxide (NO) under iron deficiency in tomato, regulates FRO2 mRNA levels. Preliminary evidence shown 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 during iron deficiency in A. thaliana roots. Treatment with the H2O2 scavenger, catalase, produced an increase in NO and a decrease in FRO2 and FIT1 transcript levels in iron deficiency. The NADPHoxidase (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 these conditions. Results indicate 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.