Bases moleculares de la regulación de la respuesta a la deficiencia de hierro en plantas con Estrategia tipo I

Resumo

Iron (Fe) is an essential microelement for plants that is necessary for important physiological processes such as photosynthesis, respiration and nitrogen assimilation (Marschner 1995). Iron is also an essential nutrient for animals and humans, who get it from plants. Low availability of soil iron to plants leads to iron deficiency which causes chlorosis.Iron chlorosis is manifested mainly as internervial yellowing of the youngest leaves, and leads to a decrease in photosynthesis and organic matter accumulation which results in a decrease in growth and productivity of affected crops (Chaney 1984). To facilitate the acquisition of iron from the soil, plants have developed different strategies. The strategy I is used by all plants except grasses (Römheld and Marschner 1986; Curie and Briat 2003, Kobayashi and Nishizawa 2012). The main characteristic of Strategy I plants, on which this work is focused, is the need to reduce the Fe3+, the most abundant form of iron in the soil, to Fe2+, prior to its absorption. This reduction occurs by a reductase enzyme, located in the membranes of the epidermal cells of the root, whose gene has been cloned in Arabidopsis (AtFRO2; Robinson et al. 1999), and other species, such as cucumber (CsFRO1; Waters et al . 2007) and tomato (SlFRO1, Li et al. 2004). Once the iron has been reduced, it is transported into the cells by means of an iron transporter located in the membrane of the epidermal cells of the root. The gene encoding the iron transporter has also been cloned in Arabidopsis (AtIRT1; Eide et al. 1996), and other species, such as cucumber (CsIRT1; Waters et al. 2007) and tomato (SlIRT1; Eckhardt et al. 2001). These iron acquisition genes are regulated at the transcriptional level by FIT, a bHLH type transcription factor in Arabidopsis, which is homologous to tomato FER, and acts together with two other transcription factors named bHLH39 bHLHH38 (Colangelo and Guerinot, 2004; Jakoby et al. 2004; Yuan et al. 2008; Bauer et al. 2007). 9...