At MYB 93 is a novel negative regulator of lateral root development in Arabidopsis

• Published in: The New phytologist Vol. 203; no. 4; pp. 1194 - 1207
• Main Authors: Gibbs, Daniel J., Voß, Ute, Harding, Susan A., Fannon, Jessica, Moody, Laura A., Yamada, Erika, Swarup, Kamal, Nibau, Candida, Bassel, George W., Choudhary, Anushree, Lavenus, Julien, Bradshaw, Susan J., Stekel, Dov J., Bennett, Malcolm J., Coates, Juliet C.
• Format: Journal Article
• Language: English
• Published: 01.09.2014
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.12879

Summary Plant root system plasticity is critical for survival in changing environmental conditions. One important aspect of root architecture is lateral root development, a complex process regulated by hormone, environmental and protein signalling pathways. Here we show, using molecular genetic approaches, that the MYB transcription factor At MYB 93 is a novel negative regulator of lateral root development in Arabidopsis. We identify At MYB 93 as an interaction partner of the lateral‐root‐promoting ARABIDILLO proteins. Atmyb93 mutants have faster lateral root developmental progression and enhanced lateral root densities, while At MYB 93‐overexpressing lines display the opposite phenotype. At MYB 93 is expressed strongly, specifically and transiently in the endodermal cells overlying early lateral root primordia and is additionally induced by auxin in the basal meristem of the primary root. Furthermore, Atmyb93 mutant lateral root development is insensitive to auxin, indicating that At MYB 93 is required for normal auxin responses during lateral root development. We propose that At MYB 93 is part of a novel auxin‐induced negative feedback loop stimulated in a select few endodermal cells early during lateral root development, ensuring that lateral roots only develop when absolutely required. Putative At MYB 93 homologues are detected throughout flowering plants and represent promising targets for manipulating root systems in diverse crop species.