title: Evolution of petaloidy in the zingiberales: An assessment of the relationship between ultrastructure and gene expression patterns.
abstract: BACKGROUND
  The development of petal-like organs has occurred repetitively throughout angiosperm evolution. Despite homoplasy, it is possible that common underlying molecular mechanisms are repeatedly recruited to drive the development of petaloid organs. In Zingiberales, infertile, petal-like structures replace fertile stamens, resulting in petaloidy in androecial whorls. Assuming that androecial petaloidy is a shared derived characteristic, we expect to find common ultrastructure and molecular mechanisms underlying androecial petaloidy across Zingiberales.
  
  
  RESULTS
  We show that petaloidy in Zingiberales is associated with tightly packed, protruding epidermal cells. Expression patterns for candidate genes involved in petal identity differ between the petaloid organs of Costaceae v. Cannaceae, despite similar macro- and microscopic organization. For all candidate gene families analyzed, our data suggest at least one Zingiberales-specific duplication event.
  
  
  CONCLUSIONS
  Our data suggest that the patterns of B-class gene expression across the Zingiberales do not correlate with the occurrence of petaloidy, indicating that androecial petaloidy might have evolved independently of B-class gene expression in some lineages. It is possible that gene duplication may play a role in the diversity of petaloid structures found throughout the Zingiberales. It is likely that Zingiberales petaloidy may also result from the deployment of genes other than those involved in specification of petal identity. Developmental Dynamics 244:1121-1132, 2015. © 2015 Wiley Periodicals, Inc.
authors: Programa de Pós-Graduação em Genética e Biodiversidade, Universidade Federal da Bahia, Campus Ondina, Salvador/BA, Brazil.|Departments of Plant and Microbial Biology and Integrative Biology and the University and Jepson Herbaria, University of California, Berkeley, California.
authors: Ana Maria
authors: AM
authors: Rocha de Almeida
authors: Departments of Plant and Microbial Biology and Integrative Biology and the University and Jepson Herbaria, University of California, Berkeley, California.|Corporación Colombiana de Investigación (CORPOICA), Bogotá, Colombia.
authors: Roxana
authors: R
authors: Yockteng
authors: Departments of Plant and Microbial Biology and Integrative Biology and the University and Jepson Herbaria, University of California, Berkeley, California.
authors: Chelsea D
authors: CD
authors: Specht
keywords: ABC model; conical epidermal cells; flower evolution; petal development; tropical gingers