The 30th International Conference on Arabidopsis Research (ICAR 2019)

661 / 2019-04-30 10:51:40

Phosphoethanolamine N-methyltransferase 1 contributes to maintenance of root apical meristem by affecting ROS and auxin regulated cell differentiation in Arabidopsis

auxin, Arabidopsis thaliana, choline, phosphoethanolamine N-methyltransferase (PEAMT), reactive oxygen species (ROS), root apical meristem (RAM).

Growth and Development > Growth and Development

The continuous growth of roots requires the balance between cell division and differentiation. Reactive oxygen species (ROS) and auxin are important regulators of root development by affecting cell division and differentiation. The mechanism controlling the coordinating of cell division and differentiation is not well understood. Using a forward genetic screen, we isolated a mutant, dpr2, defective in root apical meristem (RAM) maintenance. The DPR2 gene encodes phosphoethanolamine N-methyltransferase 1 (PEAMT1) that catalyzes phosphocholine biosynthesis in Arabidopsis. We characterized the primary root phenotypes of dpr2 using various marker lines, histochemical and pharmacological analysis to probe early root development.
Loss-of-function of DPR2/PEAMT1 resulted in RAM consumption by affecting root stem cell niche, division zone, elongation and differentiation zone (EDZ). The abundance of PIN-FORMED (PIN) transporters, PIN2 polar distribution and general endocytosis were impaired in the root tip of dpr2. Excess hydrogen peroxide and auxin accumulate in the EDZ of dpr2, leading to RAM consumption by accelerating cell differentiation. Suppression of ROS over-accumulation or inhibition of auxin signaling partially prevent RAM differentiation in dpr2 after choline starvation.Taken together, we conclude that the EDZ of the root tip is most sensitive to choline shortage, leading to RAM consumption through a ROS-auxin regulation module.