A team of researchers led by Jörg Kudla from the Institute of Biology and Biotechnology at the University of Münster are the first to demonstrate, using the model plant thale cress (Arabidopsis thaliana), how plants perceive manganese deficiency and which processes subsequently take place in the plant at the molecular level.
source https://www.lifetechnology.com/blogs/life-technology-science-news/plants-use-their-roots-to-measure-manganese-concentration-available-in-the-soil