Thais C De Barros1,2, Giseli D Pedersoli1,2, Juliana V Paulino3, Simone P Teixeira4,2. 1. Programa de Pós-Graduação em Biologia Comparada, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Avenida Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil. 2. Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP, Avenida do Café, s/n., Ribeirão Preto, SP 14040-903, Brazil. 3. Universidade Federal do Rio de Janeiro, Faculdade de Farmácia, Centro de Ciências da Saúde, Departamento de Produtos Naturais e Alimentos, Av. Prof Paulo Rocco s/n-Bl A 2°, Ilha do Fundão, Rio de Janeiro, RJ 21941-902, Brazil. 4. Programa de Pós-Graduação em Biologia Comparada, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Avenida Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil spadua@fcfrp.usp.br.
Abstract
PREMISE OF THE STUDY: Pentaclethra and Dimorphandra (Leguminosae) have long been considered a possible enigmatic link between caesalpinioids and mimosoids because they both have an imbricate calyx and heteromorphic androecium, floral features that are rare among mimosoids but common among caesalpinioids. This study compared the developing flowers of Dimorphandra mollis and Pentaclethra macroloba to determine whether the shared floral conditions also have the same ontogenetic origin. METHODS: Buds of different sizes and flowers were processed for surface (scanning electron microscopy) and histological (light microscopy) examination. KEY RESULTS: The floral meristem initiates five sepal primordia in a modified helical order in both species. The median sagittal sepal is adaxial. The overlap of the sepals during elongation culminates with the formation of the imbricate calyx. Heteromorphic androecia arise in the intermediate stages of development. In P. macroloba, the fertile pollen-bearing stamens are antesepalous, robust and short, and the anthers carry a robust apical gland; the staminodes are long and white with a vestigial apical gland. In contrast, in D. mollis the fertile pollen-bearing stamens are antepetalous without glands and as long as the staminodes. The staminodes are thinner with an expanded apical region. CONCLUSIONS: The imbricate calyx and the heteromorphic androecium in the studied species originated via distinct pathways, favoring the hypothesis of homoplasy of these conditions. The pathways observed in P. macroloba are more similar to those observed in caesalpinioids than to those observed in mimosoids, indicating that although the floral development differs between the species studied, it supports the basal placement of Pentaclethra among mimosoids.
PREMISE OF THE STUDY: Pentaclethra and Dimorphandra (Leguminosae) have long been considered a possible enigmatic link between caesalpinioids and mimosoids because they both have an imbricate calyx and heteromorphic androecium, floral features that are rare among mimosoids but common among caesalpinioids. This study compared the developing flowers of Dimorphandra mollis and Pentaclethra macroloba to determine whether the shared floral conditions also have the same ontogenetic origin. METHODS: Buds of different sizes and flowers were processed for surface (scanning electron microscopy) and histological (light microscopy) examination. KEY RESULTS: The floral meristem initiates five sepal primordia in a modified helical order in both species. The median sagittal sepal is adaxial. The overlap of the sepals during elongation culminates with the formation of the imbricate calyx. Heteromorphic androecia arise in the intermediate stages of development. In P. macroloba, the fertile pollen-bearing stamens are antesepalous, robust and short, and the anthers carry a robust apical gland; the staminodes are long and white with a vestigial apical gland. In contrast, in D. mollis the fertile pollen-bearing stamens are antepetalous without glands and as long as the staminodes. The staminodes are thinner with an expanded apical region. CONCLUSIONS: The imbricate calyx and the heteromorphic androecium in the studied species originated via distinct pathways, favoring the hypothesis of homoplasy of these conditions. The pathways observed in P. macroloba are more similar to those observed in caesalpinioids than to those observed in mimosoids, indicating that although the floral development differs between the species studied, it supports the basal placement of Pentaclethra among mimosoids.
Authors: Jamile Marques Casanova; Domingos Cardoso; Claudia Franca Barros; Haroldo Cavalcante de Lima; Karen L G De Toni Journal: PeerJ Date: 2022-09-08 Impact factor: 3.061
Authors: Kester Bull-Hereñu; Patricia Dos Santos; João Felipe Ginefra Toni; Juliana Hanna Leite El Ottra; Pakkapol Thaowetsuwan; Julius Jeiter; Louis Philippe Ronse De Craene; Akitoshi Iwamoto Journal: Plants (Basel) Date: 2022-02-28