Developmental and Structural Section
Almeida, Ana Maria , Otoni, Wagner , Yockteng, Roxana , Specht, Chelsea .
Gingers BCs: The role of MADS-box genes in floral evolution in the Zingiberales.
Despite the vast diversity of angiosperm floral forms, studies on the evolution of floral development have focused in few model species and a limited number of floral shapes. In order to fully understand the evolution of floral form in the angiosperms, the study of new systems with different morphological traits is fundamental. In the classical model of flower development - the ABC model - combinatorial expression of A, B, and C class MADS box genes determine the identity of the floral organs. B (DEF/AP3 and GLO/PI) and C (AG) class genes, in particular, are involved in the determination of petal, stamen and gynoecium identity. The Zingiberales - an order of tropical commelinid monocots - contains approximately 2,500 species roughly divided into two groups: the banana (Musaceae, Lowiaceae, Streliziaceae, Heliconiaceae), and the ginger (Costaceae,Zingiberaceae, Cannaceae, Marantaceae) groups. In the Zingiberales changes in floral form are mainly due to changes in the petal and stamen whorls: the acquisition of a complete differentiation between the first (sepals) and second (petals) whorls after the divergence of the banana lineage; the impressive reduction in the number of fertile stamens in the ginger group; and the acquisition of a novel floral structure, the labellum, as a result of the fusion of infertile stamens in Zingiberaceae and Costaceae. By taking a candidate gene approach, we asked: Are B and C class genes correlated with changes in floral morphology in the Zingiberales? It is evident from our results that B and C class genes expanded within the Zingiberales. Evolution of both GLO/AP3 and AG gene families suggest a Zingiberales-specific duplication event, right after its divergence from the other commelinid monocots. Our results support the idea that B and C class gene family expansion and functional diversification are correlated to the main morphological changes in Zingiberales flowers. However, functional studies are still needed to address whether B and C class genes are causally related to such changes.
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1 - University of California at Berkeley, Plant and Microbial Biology, 111 Koshland Hall, Berkeley, CA, 94720-3120, US
2 - Universidade Federal de Viçosa, Departamento de Biologia Vegetal, Departamento de Biologia Vegetal - UFV , Viçosa, Minas Gerais, 36570-000, BR
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 2:00 PM