A research group led by Kensuke Kawade, a specially appointed associate professor at the Institute of Basic Biology, creates a concentration gradient by the physical phenomenon of diffusion of protein "AN3" in plant leaves, and the time and place of cell division are determined accordingly. I found that.This achievement is a result of joint research with the University of Tokyo, Rikkyo University, and the Jacques Monod Institute in France.
"Morphogen" is a chemical substance such as a protein that determines the fate of cells according to its concentration. It is produced in a limited number of cells and spreads from there to the surroundings to create a concentration gradient.Half a century ago, this "morphogen concentration gradient" was proposed to be explained by diffusion, which is a simple physical phenomenon, but many unexplained concentration gradients were found, and the application of the diffusion model was limited.
Plants have a structure called plasmodesma that connects cells.The research group is considering the application of the diffusion model to the mass transport network through plasmodesma.Microscopic experiments using leaves (fluorescence recovery after fluorescence fading) revealed that protein migration within the plasmodesma is a physical diffusion phenomenon.Furthermore, by quantifying the diffusivity of the entire leaf, the overall picture of the mass transport network was clarified, and a diffusion model in the leaf was constructed.
The research group has already elucidated that AN3 is a transcriptional conjugation factor that regulates gene on / off and regulates the frequency of leaf cell division according to its concentration while moving between cells.This time, the relationship between the concentration gradient created by AN3 and the cell division frequency from the leaf stalk to the leaf tip was shown, and it was clarified that the mechanism of the concentration gradient can be fully explained by the diffusion model by experimental theoretical analysis.
Future tasks will be to elucidate the application of the findings obtained from plants to animals, the relationship between the diffusion model and environmental changes, and other factors that determine the shape and size of organs.
Paper information:[Biophysical Journal] Spatially different tissue-scale diffusivity shapes ANGUSTIFOlIA3 gradient in growing leaves
