Loading video... VIDEO: Illustrates that differential cell permeability is the key to creating the exogenous-GA-generated gradient. Technical detail: The time-course shows a root treated with nlsGPS1 growing in Rootchip18S with GA at standard (pH... view more Credit: Sainsbury Lab, University of Cambridge and University of Nottingham The research team that developed a biosensor that first recorded that a distinct gradient of the plant growth hormone gibberellin correlated with plant cell size has now revealed how this distribution pattern is created in roots. Starting when a plant embryo forms within a seed and continuing throughout the plant lifecycle, undifferentiated stem cells undergo radical transformations into specialised root, stem, leaf and reproductive organ cells. This transformation relies on a suite of molecules called phytohormones that, much like human hormones, can move between cells and tissues and trigger distinct biological processes across the bodyplan. While it was not known at the time, mutations involving the gibberellin class of phytohormones were behind the development of many of the high-yielding semi-dwarf wheat and rice varieties that helped drive the Green Revolution in the 1950s and 60s.