In flanders, lettuce farmers create a yearly turnover of 37 million euro, making it the regions second most grown vegetable. Lettuce growth is optimal at temperatures ranging between 20°C and 25°C, making it possible for farmers to grow it up to a consumable size in six weeks during spring and summer. During the winter time on the other hand, this process takes up to four months. A promising discipline to promote plant growth under stress conditions is the use of plant growth promoting rhizobacteria (PGPR). These are bacteria that live on and inside the plant's roots and that often interact intimately with their host, by providing it with nutrients or protecting it against disease. In this project we want to isolate these PGPR out of the lettuce root and evaluate them for their plant growth promoting potential by adding and overdose of them to the plants. Growth promoting strains will be combined into a consortium to obtain more robust and effective results. In addition, we want to know which plant associated molecular pathways are triggered by these bacteria to promote the plant's growth. The above mentioned experiments will provide us with insights into which bacteria live inside lettuce roots, which of these bacteria can promote lettuce growth and how they influence the plant's molecular pathways to do so. This project will significantly aid lettuce farmers living in temperate climate areas by increasing the crop's turnover rate during the cold season.