Abscisic acid is involved in plant responses to iron deficiency

RAMIREZ LEONOR; LAMATTINA LORENZO

Congreso; 15th International Symposium on Iron Nutrition and Interactions in Plants; 2010

Iron is an essential and commonly limited nutrient for plants in many cultivated areas. Iron is essential because it takes part in proteins that are central for fundamental metabolic processes in plants. When iron availability is limited, plants trigger physiological and morphological responses to increase its acquisition and adapt to insufficient iron conditions. Dicotyledoneous and monocotyledoneous non-graminaceous plants induce a series of metabolic responses when exposed to restricted iron availability that include soil acidification, increase of Fe3+ reduction through ferric chelate reductase (FRO) and Fe2+ transport through iron transporters (IRT). Plants exposed to iron deficiency also increase root absorption surface by triggering root hair proliferation. It is well known that plant responses to different stresses are often mediated by transduction pathways regulated by the phytohormone abscisic acid (ABA). The purpose of this research was to study the role of ABA during iron deficiency in Arabidopsis thaliana. We found that ABA content increases in roots but not in leaves of Arabidopsis plants growing in iron deficient conditions suggesting that ABA could be involved in plant responses to iron deficiency. The inhibitor of ABA synthesis fluridone diminished FRO activity as well as AtFRO2 and AtIRT1 transcript accumulation induced by iron deprivation. ABA treatment increased iron content in Arabidopsis plants, irrespective of the plant iron nutritional status. In addition, ABA exogenously applied enhanced the acidification of the rhizosphere and the root hair density which could be accounting for the ABA-mediated iron accumulation in the plant. Taken together, these results suggest that ABA, in addition to its well characterized role in drought stress, is an important player regulating plant responses to iron nutritional imbalance.