Two MYB Proteins in a Self-Organizing Activator-Inhibitor System Produce Spotted Pigmentation Patterns

Curr Biol. 2020 Mar 9;30(5):802-814.e8. doi: 10.1016/j.cub.2019.12.067. Epub 2020 Feb 20.


Many organisms exhibit visually striking spotted or striped pigmentation patterns. Developmental models predict that such spatial patterns can form when a local autocatalytic feedback loop and a long-range inhibitory feedback loop interact. At its simplest, this self-organizing network only requires one self-activating activator that also activates a repressor, which inhibits the activator and diffuses to neighboring cells. However, the molecular activators and inhibitors fully fitting this versatile model remain elusive in pigmentation systems. Here, we characterize an R2R3-MYB activator and an R3-MYB repressor in monkeyflowers (Mimulus). Through experimental perturbation and mathematical modeling, we demonstrate that the properties of these two proteins correspond to an activator-inhibitor pair in a two-component, reaction-diffusion system, explaining the formation of dispersed anthocyanin spots in monkeyflower petals. Notably, disrupting this pattern impacts pollinator visitation. Thus, subtle changes in simple activator-inhibitor systems are likely essential contributors to the evolution of the remarkable diversity of pigmentation patterns in flowers.

Keywords: Erythranthe; Mimulus; anthocyanin; developmental patterning; flower color; genome editing; monkeyflower; natural variation; pigmentation; reaction-diffusion.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Mimulus / genetics
  • Mimulus / physiology*
  • Pigmentation / genetics
  • Pigments, Biological / genetics*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Proto-Oncogene Proteins c-myb / genetics*
  • Proto-Oncogene Proteins c-myb / metabolism
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism


  • Pigments, Biological
  • Plant Proteins
  • Proto-Oncogene Proteins c-myb
  • Transcription Factors