AHP6 inhibits cytokinin signaling to regulate the orientation of pericycle cell division during lateral root initiation

• Published in: PloS one Vol. 8; no. 2; p. e56370
• Main Authors: Moreira, Sofia, Bishopp, Anthony, Carvalho, Helena, Campilho, Ana
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14.02.2013; Public Library of Science (PLoS)
• Subjects: Arabidopsis; Arabidopsis - cytology; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biology; Cell Division; Cytokinins - metabolism; Developmental stages; Efflux; Gene Expression Regulation, Plant; Gibberellins; Histidine; Indoleacetic Acids - metabolism; Kinases; Localization; Membrane Transport Proteins - metabolism; Pattern formation; Patterning; Pin1 protein; Plant Roots - growth & development; Primordia; Protein Transport; Roots; Signal Transduction; Signaling
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0056370

In Arabidopsis thaliana, lateral roots (LRs) initiate from anticlinal cell divisions of pericycle founder cells. The formation of LR primordia is regulated antagonistically by the phytohormones cytokinin and auxin. It has previously been shown that cytokinin has an inhibitory effect on the patterning events occurring during LR formation. However, the molecular players involved in cytokinin repression are still unknown. In a similar manner to protoxylem formation in Arabidopsis roots, in which AHP6 (ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN 6) acts as a cytokinin inhibitor, we reveal that AHP6 also functions as a cytokinin repressor during early stages of LR development. We show that AHP6 is expressed at different developmental stages during LR formation and is required for the correct orientation of cell divisions at the onset of LR development. Moreover, we demonstrate that AHP6 influences the localization of the auxin efflux carrier PIN1, which is necessary for patterning the LR primordia. In summary, we show that the inhibition of cytokinin signaling through AHP6 is required to establish the correct pattern during LR initiation.