Science - USA (2021-07-09)

Growth dynamics define cauliflower and
Romanesco curd structures
Our work inArabidopsisoffers a conceptual
framework to explain how inflorescence archi-
tecture emerges from coupling a floral GRN

to morphodynamic parameters. We wondered

whether modifications affecting components

of this framework could also explain the archi-

tecture of the cauliflowers that arose during

domestication, namely the edibleB. oleracea

(Bo)var.botrytis (Bob)and its Romanesco var-

iant. Whether similar genetic defects as inAra-

bidopsisare responsible for curd development

inB. oleraceais still debated ( 4 , 5 ). To further in-

vestigate this point, we analyzed RNA-sequencing

196 9JULY2021•VOL 373 ISSUE 6551 sciencemag.org SCIENCE

A

State (t)

=

[S,A,L,T,F, Aux]

L-System

model

GRN

model

State (t+Δt)

[S,A,L,T,F,Aux]

Δt

New inherited state

State (t) Δt [S',A',L',T',F', Aux']

Updated

[]S,A,L,T

at t+Δt

K N

M

J

O

L

BDWT C Ify tfl1 E ap1 cal

F

G

H

I

Meristem

Internode

Flower

Leaf

1

2

3

123 Meristem

order

Fig. 4. Simulation and assessment of a GRN-based plant development model.
(A) Schematic representation of the multiscale model ofArabidopsisdevelop-
ment. Each meristem state is composed of signal levels (auxin, F) and a GRN steady
state. At timet, the plant is made up of a collection of organs (left). At timet+Dt(right),
the model updates the signal levels and GRN state in each meristem. The steady
state defines the identity of the meristems (vegetative, inflorescence, or flower) used to
compute meristem lateral productions. Green numbers indicate meristem order.

(BtoE) Plant morphologies obtained in the WT (B),lfy(C),tfl1(D), andap1 cal(E)

simulations. (FtoI) Simulated morphologies with constant [(F) and (H)] or increased

[(G) and (I)] meristem production rate in a simplified model [(F) and (G)] and in the

Arabidopsismodel [(H) and (I)]. (JtoO) Light micrographs [(J), (L), and (N)] and

SEM [(K), (M), and (O)] of cauliflower structures inArabidopsis ap1 cal[(J) and

(K)],Arabidopsis ap1 cal clv3[(L), (M), and (O)], and Romanesco (N). The

uninducedAP1:GRtransgene is present in plants (J) to (M). Scale bars, 500mm.

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