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Plant development and evolution: Lessons learned from candidate genes

Kramer, Elena M [1], Jaramillo, M. Alejandra [2].

Variations on a theme: The evolutionary genetics of petal identity..

The elucidation of the genetic program controlling floral organ identity has created many new opportunities for understanding the evolution of floral morphology. In particular, it has been suggested that many aspects of floral diversity could have been generated through simple shifts in the functional domains of the homeotic organ identity genes. Members of the lower eudicot family Ranunculaceae are very well suited for testing this hypothesis due to their wide array of perianth types. In many genera, such as Aquilegia (columbine), two whorls of morphologically distinct petals are present in the flower, suggesting that two separate petal identity programs may be functioning. In other taxa, only one type of petals are present, although these may occupy the first whorl, as in Clematis, or the second, as in Ranunculus. The genus Aquilegia is especially useful in the study of this phenomenon due to its small diploid genome and the availability of many floral homeotic mutants. We have identified homologs of the Arabidopsis genes APETALA3 (AP3), PISTILLATA (PI), AGAMOUS (AG), APETALA1 (AP1) and SEPALLATA3 (SEP3) in Aquilegia, and have begun to characterize their expression patterns in both wildtype and mutant plants. It appears that gene duplications which occurred in the AP3 lineage before the diversification of the Ranunculaceae have facilitated the evolution of multiple forms of petaloid organs in this new model species. This theory is being evaluated through genetic analyses of homeotic mutants that affect the identity of petaloid organs.

1 - Harvard Univerisity, Organismic and Evolutionary Biology, 16 Divinity Ave, Biolabs 1109, Cambridge, Massachusetts, 02138, USA
2 - Universidade Federal do Rio de Janeiro, Bioquimica Medica, Av. Bahuinia 400, CCS, bloco D, subssolo, sala 05, Cidade Universitaria, Rio de Janeiro, RJ, 21941 590, Brazil

developmental genetics
Floral morphology
gene expression
MADS box genes.

Presentation Type: Symposium
Session: 44-4
Location: Ballroom 1 (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 10:00 AM
Abstract ID:23

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