Molecular networks underpinning root development in Arabidopsis and crops

植物根构型的控制是保证植物在不断变化的环境条件下生存的关键。Coates实验室已经证明，拟南芥转录因子AtMYB93只定位于根内皮层中的几个特定细胞，调节根分支或侧根发育(Gibbs等人，2014年新植物学家)。AtMYB93的表达是由植物激素生长素和脱落酸诱导的，也受环境控制。AtMYB93负调控根的分枝，使其成为第一个生长素诱导的侧根发育负调控因子，表明它是负反馈循环的一部分，确保只有在绝对需要的情况下才会产生新的根。初步的生物信息学分析表明，AtMYB93与上调suberin的生物合成密切相关。Suberin定位于内胚层的特定区域，这是最近与侧根发育有关的细胞层，AtMYB93也显示出类似的内胚层定位。我们的初步数据显示，Atmyb93突变体对非生物胁迫的反应发生了复杂的变化，包括盐胁迫和缺硫。这其中的确切机制尚不清楚，但可能涉及由于Suberin分布的变化以及随后的地上部生理变化而导致的根内屏障特性的变化。该建议的主要目标是(I)在分子水平上了解AtMYB93如何发挥其功能，(Ii)了解改变AtMYB93如何影响根屏障特性，从而影响整个植物的生理，以及(Iii)确定作物中的MYB93同源物是否是操纵作物根系发育以进行作物改良的良好靶标。

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.