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Genetic interactions among floral homeotic genes of Arabidopsis

Bowman, John L. and Smyth, David R. and Meyerowitz, Elliot M. (1991) Genetic interactions among floral homeotic genes of Arabidopsis. Development, 112 (1). pp. 1-20. ISSN 0950-1991.

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We describe allelic series for three loci, mutations in which result in homeotic conversions in two adjacent whorls in the Arabidopsis thaliana flower. Both the structure of the mature flower and its development from the initial primordium are described by scanning electron microscopy. New mutations at the APETALA2 locus, ap2-2, ap2-8 and ap2-9, cause homeotic conversions in the outer two whorls: sepals to carpels (or leaves) and petals to stamens. Two new mutations of PISTILLATA, pi-2 and pi-3, cause second and third whorl organs to differentiate incorrectly. Homeotic conversions are petals to sepals and stamens to carpels, a pattern similar to that previously described for the apetala3-1 mutation. The AGAMOUS mutations, ag-2 and ag-3, affect the third and fourth whorls and cause petals to develop instead of stamens and another flower to arise in place of the gynoecium. In addition to homeotic changes, mutations at the APETALA2, APETALA3 and PISTILLATA loci may lead to reduced numbers of organs, or even their absence, in specific whorls. The bud and flower phenotypes of doubly and triply mutant strains, constructed with these and previously described alleles, are also described. Based on these results, a model is proposed that suggests that the products of these homeotic genes are each active in fields occupying two adjacent whorls, AP2 in the two outer whorls, PI and AP3 in whorls two and three, and AG in the two inner whorls. In combination, therefore, the gene products in these three concentric, overlapping fields specify the four types of organs in the wild-type flower. Further, the phenotypes of multiple mutant lines indicate that the wild-type products of the AGAMOUS and APETALA2 genes interact antagonistically. AP2 seems to keep the AG gene inactive in the two outer whorls while the converse is likely in the two inner whorls. This field model successfully predicts the phenotypes of all the singly, doubly and triply mutant flowers described.

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Meyerowitz, Elliot M.0000-0003-4798-5153
Additional Information:© 1991 Company of Biologists. {Accepted 14 January 1991) We thank our colleagues, Laura Brockman, Caren Chang, Gary Drews, Bruce Hamilton, Tom Jack, Leslie Sieburth, Alex van der Bliek and Detlef Weigel for insightful discussions and critical review; Ken Feldmann for providing the ag-2 allele; and Pat Coen of the Electron Microscope Facility at Caltech for technical advice. This study was assisted by National Science Foundation grant DCB-8703439 to E.M.M. J.L.B. is partially supported by training grant 5T32-GM07616 of the National Institutes of Health.
Funding AgencyGrant Number
NIH Predoctoral Fellowship5T32-GM07616
Subject Keywords:flower development, Arabidopsis, homeotic genes
Issue or Number:1
Record Number:CaltechAUTHORS:BOWdev91
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Official Citation:Genetic interactions among floral homeotic genes of Arabidopsis J.L. Bowman, D.R. Smyth, E.M. Meyerowitz Development 1991 112: 1-20
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12448
Deposited By: Archive Administrator
Deposited On:02 Dec 2008 17:59
Last Modified:03 Oct 2019 00:28

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