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A genetic framework for floral patterning

Abstract

The initial steps of flower development involve two classes of consecutively acting regulatory genes. Meristem-identity genes, which act early to control the initiation of flowers, are expressed throughout the incipient floral primordium. Homeotic genes, which act later to specify the identity of individual floral organs, are expressed in distinct domains within the flower. The link between the two classes of genes has remained unknown so far. Here we show that the meristem-identity gene LEAFY has a role in controlling homeotic genes that is separable from its role in specifying floral fate. On the basis of our observation that LEAFY activates different homeotic genes through distinct mechanisms, we propose a genetic framework for the control of floral patterning.

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Figure 1: Activity domains of ABC floral homeotic genes and LFY expression.
Figure 2: In vitro activity of LFY protein and LFY:VP16 constructs.
Figure 3: Phenotypes of wild-type, mutant and transgenic plants.
Figure 4: Expression of AP1, AG, AP3 and LFY in wild-type (a–d) and LFY:VP16 transgenic (e–h) plants.
Figure 5: AP1::GUS and AG::GUS expression outside flowers.
Figure 6: LFY and UFO together induce AP3 expression in seedlings.
Figure 7: Model for ABC gene activation by LFY.

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Acknowledgements

We thank D. S. Wolfe, K. Bomblies, V. Hedquist and T. Nguyen for technical assistance; M. Blázquez, E. Bier, A. Colon, C. Fankhauser, G. Gocal, M. Goulding, D. Jackson, I.Kardailsky, M. Ng and M. Yanofsky for discussions, technical advice and unpublished results; T. Jack, B. Krizek, A.Mandel and L. Sieburth for reporter lines; P. O'Hare and S. Triezenberg for VP16 plasmids; and G.Ruvkun for inspiring the VP16 experiment. This work was supported by fellowships from Bourse Lavoisier du Ministère Français des Affaires Etrangères (F.P.), the Human Frontier Science Program Organization (F.P., O.N., M.A.B.), and the Parson and Aron Foundation (I.L.), and by grants from the National Science Foundation and US Department of Agriculture (to D.W.). D.W. is an NSF Young Investigator and receives support from the Samuel Roberts Noble Foundation, Agritope and ForBio.

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Correspondence to Detlef Weigel.

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Parcy, F., Nilsson, O., Busch, M. et al. A genetic framework for floral patterning. Nature 395, 561–566 (1998). https://doi.org/10.1038/26903

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