It takes two..... or more to get the perfect root system architecture?

Plant shape is a primary determinant of productivity and yield. The above ground plant shape controls the light interception and photosynthesis, whereas the below ground root architecture is important for the interaction with the soil abiotic and biotic factors, anchoring in the soil and uptake of water and nutrients. The plant root system is determined by roots with different origins, i.e. the primary root that has been initiated during embryogenesis while secondary roots are formed post embryonically. These consist of lateral roots that are primed in the primary root meristem using the PLT3,5,7 pathway (pathway 1), and secondary roots mediated by the WOX11 pathway (pathway 2). Intriguingly, whereas these pathways are initiated by different cues and activate a different set of transcription factors, preliminary data shows that the downstream pathways overlap and activate the same set of stem cell niche factors. The shape of the plant root system can also be affected by plant growth-promoting rhizobacteria (PGPR). In this study I will use a Pseudomonas strain that causes primary root arrest, but induces increased lateral root formation most likely by activating “sleeping” lateral root primordia (pathway 3). To get a better understanding how we can shape plant roots, I will unravel key genetic factors involved in specification and growth of new primordia and how they are controlled by environmental factors.