Mutations affecting stomatal production



The too many mouths and four lips mutations affect stomatal production in Arabidopsis.

by Yang M., Sack F. D. (1995)

in Plant Cell 7:2227–2239. – doi: 10.1105/tpc.7.12.2227 –

PubMed CentralView ArticlePubMed – PubMed Abstract | CrossRef Full Text | Google Scholar


Stomata regulate gas exchange through the aerial plant epidermis by controlling the width of a pore bordered by two guard cells. Little is known about the genes that regulate stomatal development.

We screened cotyledons from ethyl methanesulfonate-mutagenized seeds of Arabidopsis by light microscopy to identify mutants with altered stomatal morphology.

Two mutants, designated too many mouths (tmm) and four lips (flp), were isolated with extra adjacent stomata.

The tmm mutation results in stomatal clustering and increased precursor cell formation in cotyledons and a virtual absence of stomata in the inflorescence stem.

The flp mutation results in many paired stomata and a small percentage of unpaired guard cells in cotyledons.

The double mutant (tmm flp) exhibits aspects of both parental phenotypes.

Both mutations appear to affect stomatal production more than patterning or differentiation. tmm regulates stomatal production by controlling the formation, and probably the activity, of the stomatal precursor cell.


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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