Ectopic ferredoxin I protein promotes root hair growth through induction of reactive oxygen species in Arabidopsis thaliana.

Ferredoxin I (Fd-1) is a protein existing in green tissues as an electron carrier for photosynthesis. Reactive oxygen species (ROS) are generated from an over-accumulation of electrons in photosynthetic electron chains. In previous studies, plant ferredoxin-like protein (PFLP) transgenic plants could be made resistant to virulent pathogens, by inducing the generation of ROS. The generation of ROS is closely associated with root hair development, increasing with the elongation of root hairs. We propose that an ectopic expression of pflp may alter root hair development through the enhanced generation of ROS. In this report, Arabidopsis transformed with pflp was generated to determine the potential role of PFLP in root development. Transgenic Arabidopsis exhibited longer root hairs with a significant increase in endogenous H(2)O(2) compared with wild type. The growth of transgenic lines in root hairs was inhibited when treated with NADPH oxidase inhibitor. Results suggest that an over-expression of pflp had enhanced the accumulation of H(2)O(2) in the roots and further promoted the growth of root hairs. Transcriptional activities of root hair development-related and redox-regulated genes were mediated through increased levels of ROS, to alter the growth of transgenic lines in root hairs. In summary, we propose that an ectopic expression of pflp promotes root hair growth, resulting from an enhancement of ROS production.