Science - USA (2019-08-30)

Y

aowu Yuan’s passion for monkey-

flowers began in 2004 with a

slideshow. Then a budding plant

taxonomist at the University of

Washington in Seattle and an avid

hiker, he was amazed at the variety

of wildflowers he saw on his out-

ings in the Cascade mountains.

Like Charles Darwin, he was vexed

by what Darwin called an abominable mys-

tery: How did nature generate such a diver-

sity of flower colors and forms? During a

campus seminar, Yuan encountered a plant

that he thought might yield answers. Uni-

versity of Washington plant molecular biolo-

gist H. D. “Toby” Bradshaw and his graduate

student showed slides documenting as much

floral diversity within a single monkeyflower

species as Yuan had seen in the meadows

and streambanks of the Cascades—all gen-

erated by mutating the genome of this one

Mimulus species.

The revelation changed the course of

Yuan’s research because he realized such

mutants could lead to a better understand-

ing of flower development in all plants. Since

starting a faculty job at the University of Con-

necticut (UConn) in Storrs 6 years ago, he

has been tracking down genes that control

color, shape, size, and other traits in Mimulus

flowers—and that may have similar effects in

other plants. And he is far from the only sci-

entist to have fallen under the spell of a plant

best known as a weed that thrives where few

plants, even other weeds, can grow—around

abandoned copper mines and hot springs

and in other inhospitable, mineral-laden soil.

Like plant scientists’ traditional lab work-

horse, the mustard weed Arabidopsis thali-

ana, monkeyflowers grow fast, produce a

lot of seeds, and have a simple genome—

appealing traits for lab studies. But their ex-

plosion of flower colors and forms, diverse

lifestyles, and extraordinary hardiness—

dramatic contrasts to the unassuming Ara-

bidopsis—have seduced researchers studying

plant evolution and adaptations. “You can

use Mimulus to study traits that don’t even

exist in Arabidopsis,” Yuan says.

More than 40 labs now focus on select

members of Mimulus, a number that has

doubled in the past decade, says Andrea

Sweigart, an evolutionary geneticist at the

University of Georgia in Athens. The National

Science Foundation (NSF) has funded both

854 30 AUGUST 2019 • VOL 365 ISSUE 6456 sciencemag.org SCIENCE

PHOTO: DENA GROSSENBACHER

FEATURES

By Elizabeth Pennisi

THE ALLURE OF

MONKEYFLOWERS

A tough, diverse, colorful weed used in evolutionary studies

is becoming a key model for plant biology

Published by AAAS