Plant Molecular Biology 42: 115–149, 2000.
© 2000 Kluwer Academic Publishers. Printed in the Netherlands.
A short history of MADS-box genes in plants
, Annette Becker, Alexandra Di Rosa, Akira Kanno, Jan T. Kim, Thomas
Münster, Kai-Uwe Winter and Heinz Saedler
Max-Planck-Institut für Züchtungsforschung, Abteilung Molekulare Pﬂanzengenetik, Carl-von-Linn´e-Weg 10,
50829 Köln, Germany (
author for correspondence)
Key words: angiosperm, development, evolution, fern, gymnosperm, MADS-box gene
Evolutionary developmental genetics (evodevotics) is a novel scientiﬁc endeavor which assumes that changes
in developmental control genes are a major aspect of evolutionary changes in morphology. Understanding the
phylogenyof developmental control genes may thus help us to understand the evolution of plant and animal form.
The principles of evodevotics are exempliﬁed by outlining the role of MADS-box genes in the evolution of plant
reproductive structures. In extant eudicotyledonous ﬂowering plants, MADS-box genes act as homeotic selector
genes determining ﬂoral organ identity and as ﬂoral meristem identity genes. By reviewing current knowledge
about MADS-box genes in ferns, gymnosperms and different types of angiosperms, we demonstrate that the phy-
logeny of MADS-box genes was strongly correlated with the origin and evolution of plant reproductive structures
such as ovules and ﬂowers. It seems likely, therefore, that changes in MADS-box gene structure, expression and
function have been a major cause for innovations in reproductive developmentduring land plant evolution, such as
seed, ﬂower and fruit formation.
Introduction: on the origin of novel structures
We explain here what evolutionary developmental ge-
netics (evodevotics) is, and how it may help us to
understand the evolution of diversity and complex-
ity in the living world. We present one of the most
important corollaries of evodevotics, that changes in
developmental control genes might be a major cause
of evolutionary changes in morphology.
Higher organisms such as plants and animals im-
press us with their complexity and their diversity. Take
plants as an example. Every tiny weed you can ﬁnd on
a little walk around the corner is by far more complex
than anything we know from outside the living world,
and the diversity of plants is breath-taking ranging, for
example, from huge oak trees to microscopic green
algae on their bark. Understanding the laws of nature
The MADS homepage: http://www.mpiz-koeln.mpg.de/mads/
that have generated that diversity and complexity is at
the very heart of biology.
Initially, one can try to understand complex organ-
isms from an engineer’s point of view – an attitude
which already has quite some explanatory power. For
example, interpreting leaves as efﬁcient sun-collectors
explains why these are generally ﬂat and oriented to-
wards the sun. However, functional explanations have
serious limitations in the living world. Why, for exam-
ple, do the ﬂowers of some plants have three organs
(sepals, petals or tepals) in each whorl of their peri-
anth (such as Liliaceae), while others have four (e.g.
Brassicaceae) or ﬁve (e.g. Rosaceae), if any number
of perianth organs is able to attract pollinators efﬁ-
ciently? Why do mammals usually walkonfourlimbs,
insects on six and spiders on eight, if any even number
of limbs allows efﬁcient locomotion on land?
The difﬁculties with explanations that would sat-
isfy engineers in the living world arise from the fact
that all features of living organisms are a product both
of necessity and chance during evolution . Some