Ectopic Lateral Root Branching in Fe-Deprived Maize Plants: Searching for the Genes Underpinning the Phenotype

Iron is an essential element for plant growth and productivity, whilst human and animal diets rely on iron from plant sources. It is, thus, necessary to understand the responses of plants to iron deficiency at both the physiological and morphological levels and reveal the molecular and genetic bases of these responses. Despite the large number of studies on plants’ iron deficiency responses, considerably less is known regarding the morphological and anatomical alterations in plant root systems, especially in the graminaceous plants following a chelation strategy to take up iron from their rhizosphere (Strategy II plants). It seems that plants modify their root architecture by increased formation and branching of root hairs, root-tip swelling, and enhanced lateral root formation. Especially for maize, a stress symptom observed in F-deprived plants was an ectopic lateral root branching at the terminal 5 cm of the root. In this study, one-week-old maize seedlings were placed in containers with either full nutrient solution, or nutrient solution lacking a Fe source. Control and Fe-deprived plants were grown for another 14 days, and the trait of ectopic lateral root branching was observed both on roots that emerged before the onset of Fe deprivation (i.e. primary embryonic root, secondary embryonic roots), as well as on roots that emerged after the onset of the deprivation (i.e. crown roots). In silico analysis of a quantitative trait locus known to be related to this trait of maize grown under limited Fe, unveiled several genes coding for known and unknown proteins, as well as long intergenic non-coding RNAs.