Nitric Oxide and Labile Iron Pool in Plants

Salta, Argentina

Congreso; XXXIX Annual Meeting of the Argentinean Biophysical Society, Workshop CeBEM, Latin American Protein Society Meeting; 2010

Sociedad Argentina de Biofísica

Plants are able not only to produce nitric oxide (NO)1, but also to respond to NO from environment2. Among the broad spectrum of actions of NO in biological systems we studied the effect over iron availability, since modulation of cellular Fe status is an important factor for the establishment of oxidative stress and the regulation of plant physiology. The labile iron pool is defined biochemically as a pool of redox-active Fe complexes and operationally, as a cell chelatable pool that comprises both ionic forms of Fe (Fe2+ and Fe3+) associate with a diverse population of ligands. During germination of sorghum seeds (Sorghum bicolor (L.) Moench) the presence of  NO donors lead to an increase in NO content in embryos detected by spin trapping electron paramagnetic resonance (EPR), which correlated with a higher labile iron pool as compared to control seeds.   S-nitrosothiols and nitrosyl iron complexes have been proposed as stable NO carriers capable of transporting NO to a distance several fold exceeding cell sizes3. Homogenates from sorghum embryonic axes exposed in vitro to NO donors (1 mM SNP, GSNO or DETA NONOate) lead to the generation of mononitrosyl iron complexes (MNIC) and dinitrosyl iron complexes (DNIC), that could be detected by EPR4. In summary, the changes observed in labile iron pool after NO exposure and the detection of both MNIC and DNIC during in vitro incubation of sorghum homogenates under high NO availability, lead us to suggest a role for NO in iron mobilization in plants. 1. Simontacchi M., Jasid S. and Puntarulo S., Plant Science, 167, 839-847 (2004) 2. Jasid  S., Simontacchi M. and Puntarulo S., J. Exp. Botany, 59, 3953-3962 (2008) 3. Lancaster J.R., Proc. Natl. Acad. Sci. USA, 91, 8137-8141 (1994) 4. Vanin A.F., Nitric Oxide, 21, 1-13 (2009)