Regulation of Fe deficiency responses in wt pea and some of its mutants (brzand dgl)

Abstract

Iron (Fe) participates in many essential plant functions, such as photosynthesis, respiration and nitrogen metabolism, including nodulation of legume plants. It is abundant in most soils but its availability is low, especially in calcareous soils (more than 30% of arable soils), where its solubility is very low and is frequent the incidence of Fe chlorosis. In these soils, one of the more important factors causing Fe chlorosis is bicarbonate while hypoxia, due to flooding or other causes, can aggravate its negative effects. According to the World Health Organization, the most common nutritional disorder in humans is Fe deficiency, with over 30% of the world's population affected. To solve both problems, two of the main objectives of plant Fe researchers are to obtain genotypes more efficient in Fe uptake (more tolerant to calcareous soils) and to get edible seeds with higher Fe content for human nutrition. For these goals, it is necessary to know better the mechanisms implicated in Fe uptake and their regulation. To acquire Fe from soils, plants have developed different strategies. Today, two main strategies are considered: the Strategy I, present in non graminaceous plants (dicots, non grasses monocots,…) and the Strategy II, present in graminaceous plants. When plants suffer from Fe deficiency they switch on several morphological and physiological changes in their roots, known as Fe deficiency stress responses (hereafter named Fe responses), aimed to facilitate Fe acquisition and mobilization. These responses are switched off once plants acquire enough Fe, to avoid Fe intoxication and energy lost. Since pea is a dicot plant species, this review is devoted to describe the characteristics of Fe acquisition and Fe responses in Strategy I plants, pointing out the role of some pea mutants (brz and dgl) in the studies about this Strategy.