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

First author: Baoqing Ding; Affiliations: University of Connecticut  (康涅狄格大学): Storrs, USA

Corresponding author: Yao-Wu Yuan

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.

许多生物存在视觉上醒目的斑点或条纹状色素沉着模式。发育模型预测在一个局部自催化的反馈环和一个长距离抑制反馈环互作时就可以形成这样的空间模式。最简单的状态下，该自我组织的网络仅需要一个自我激活的激活子，同时该激活子又能激活一个抑制子，该抑制能够扩散到邻近细胞中并抑制激活子。然而，完全适合这种多功能模型的分子激活子和抑制子在色素沉着系统中仍不清楚。本文中，作者在猴面花中鉴定了一个R2R3-MYB激活子和一个R3-MYB抑制子。通过试验干涉和数学建模，作者发现这两个蛋白的特性对应着一对双组分反应-扩散系统中的激活子-抑制子，该系统解释了猴面花花瓣中散状分布的花色苷斑点的形成。值得注意的是，扰乱该模式会影响传粉者的造访。因此，即使在一个简单的激活-抑制系统中微小变化也足以对植物花组织色素沉着模式的多样化演变起到促进作用。

通讯：袁耀武 (https://monkeyflower.uconn.edu)

个人简介：2000-2004年，四川大学，学士；2004-2008年，华盛顿大学，博士；2009-2010年，佐治亚大学，博士后。

研究方向：猴面花。

doi: https://doi.org/10.1016/j.cub.2019.12.067

Journal: Current Biology

Published date: February 20, 2020

p.s. 猴面花：https://www.sciencemag.org/news/2019/08/meet-monkeyflower-weed-may-hold-key-zebra-stripes-and-other-biological-mysteries