The root system of plants is important for their growth and survival. Roots anchor plants in the soil and are required for the uptake of water and nutrients. The root system of many plants consists of a long main root with regularly spaced lateral branches to optimize water and nutrient uptake. The regular pattern of lateral roots along the main root is controlled at the tip of the growing root. Here, changes in gene expression periodically make certain root cells competent to form a lateral root. The competent cells are called prebranch sites. Our lab recently revealed that the production of the plant hormone auxin at the root tip is important to produce prebranch sites. This local auxin source induces the production of a protein called MEMBRANE-ASSOCIATED KINASE REGULATOR4 (MAKR4) that is required for root branching. Our data indicate that MAKR4 could be a key factor that transmits a signal to the prebranch sites to develop into a lateral root. We will investigate how MAKR4 signaling occurs during root branching, and at what time and place it functions during lateral root formation. This information will be an important step to answer the question how the regular pattern of lateral roots is established, and has the potential to help plant breeders to improve the water and nutrient uptake of crop species