In experiments on transport tissues in plants, researchers from Heidelberg University were able to identify factors of crucial importance for the formation of the plant tissue known as phloem. According to Prof. Dr Thomas Greb of the Centre for Organismal Studies (COS), these factors differ from all previously known factors that trigger the specification of cells. The findings of the Heidelberg researchers substantially expand our understanding of the metabolic processes in plants. Their results were published in the journal Current Biology.