Molecular networks underpinning root development in Arabidopsis and crops

Control of plant root architecture is critical to ensure plant survival in the face of changing environmental conditions. The Coates lab has shown that an Arabidopsis transcription factor, AtMYB93, which is localised to just a few specific cells in the endodermis of the root, regulates root branching, or lateral root development (Gibbs et al 2014 New Phytologist). AtMYB93 expression is induced by the plant hormones auxin and abscisic acid, and is also under environmental control. AtMYB93 negatively regulates root branching, making it the first auxin-induced negative regulator of lateral root development and suggesting that it is part of a negative feedback loop that ensures that a new root is only made when absolutely required.
Preliminary bioinformatic analysis suggests that AtMYB93 is intimately involved with upregulating suberin biosynthesis. Suberin is localized in specific areas of the endodermis, a cell layer recently implicated in lateral root development, and AtMYB93 shows similar endodermal localization. Our preliminary data shows that Atmyb93 mutants have complex altered responses to abiotic stress, including salt stress and sulphur deprivation. The exact mechanism of this is unknown, but likely involves changes in barrier properties within the root due to changes in suberin distribution, and subsequent changes in shoot physiology.
The overarching aims of this proposal are (i) to understand how AtMYB93 performs its function at a molecular level, (ii) to understand how altering AtMYB93 affects root barrier properties and hence whole-plant physiology, and (iii) to determine whether MYB93 homologues in crops are good targets for manipulation of root development for crop improvement.