Neue GSA Regulatoren in Lateralwurzeln

Zusammenfassung: Plants are sessile organisms and consequently developed elaborated mechanisms to control the growth of their organs to optimize interactions with the neighboring environment. Roots are responsible for the acquisition of soil-based resources and anchorage in the substrate among others. To efficiently serve these functions, they branch out through the development of lateral roots (LRs). The LR initiation, one key process in the regulation of root architecture, has been extensively studied (Lavenus et al., 2013; Orman-Ligeza et al., 2013). However, the mechanisms controlling LRs development after initiation are poorly understood (Tian, De Smet, et al., 2014). The regulation of the growth direction in the soil is a major determinant of the root architecture. In contrast to the main root, which grows mostly vertically in the substrate as a result of a tropic response to gravity, the LRs coordinately deviate from this standard gravitropism to develop radially and optimize the exploration of the environment. The LRs can however sense gravity and have similar anatomical and physiological structures that drive a vertical growth of the main root. This implies a set of regulations specific to the LRs to finetune their endogenous gravitropism, referred as plagiotropism. The aim of this project is to understand the transcriptional regulation of the gravitropism in the LRs using a systems biology approach. We will first establish a sampling method to isolate tissues involved in i) gravi-sensing (in the columella cells of the root tip) , ii) signal transfer (in the lateral root cap and epidermis), and iii) growth response (in the elongating epidermis). We will assess the transcriptional regulations in these tissues using RNA sequencing at four different stages of the LRs elongation where a) the anatomical structures sensing gravity are differentiated, b) the root reacts to gravity for a lapse of time defining the gravitropic set angle, c) gravitropism is inhibited and the root grows radially, d) gravitropism is reactivated and the root grows in direction of the gravity vector. This research grant will cover the costs for the RNA sequencing and will thereby allow us to conduct the here proposed research. After validations, we will use bioinformatics approaches to generate networks and make a selection of potential regulatory genes. This project, aiming at understanding the transcriptional regulation of the gravitropism in the LRs will not only bring knowledge about the plagiotropism, but will also greatly contribute in understanding general processes of the regulation of the gravitropic response in plants.