IRON DEFICIENCY-INDUCED RESPONSES IN ARABIDOPSIS THALIANA ROOTS: ROLE OF ETHYLENE

NEGRI, P.*; CABALLERO, V.*; D`IPPOLITO, S.*; MASSAZZA, D.*;

Rosario, Argentina

Congreso; XLII Reunion anual Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2006

A low iron availability in soil generates a series of plant root responses that lead to the increase of iron uptake. Fe+3- reductase (FRO2) under the control of the transcription factor (FIT1) and morphologic changes in roots have been described to be induced by iron deficiency. Since different reports have involved nitric oxide (NO) and ethylene in plant iron metabolism, we decided to study the role of ethylene and its crosstalk with NO in plant root responses to iron deficiency. Plants of Arabidopsis thaliana grown in presence or absence of iron were treated with ethephon (ethylene donor) or CoCl2 (ethylene synthesis inhibitor). The morphologic analysis of the roots showed that depletion of endogenous ethylene completely inhibited roots hairs development. NO production in roots was increased by ethylene treatment and decreased when adding CoCl2. Beside, FRO2 and FIT1 expression were evaluated by semiquantitative RT-PCR. Results indicated that, while CoCl2 did not affect the FRO2 and FIT1 mRNA levels in presence or absence of iron, the ethylene addition decreased those levels. In conclusion, ethylene would play a role in root hairs development and NO production and, at less extent, would also influence FRO2 and FIT1 expression as well as FRO2 activity. [*These authors have contributed equally to this work].