Abstract Detail

Developmental and Structural Section

Coutinho, Italo Antonio Cotta Coutinho [1], Francino, Dayana Maria Teodoro [2], Santos, Marinalva Alves dos [3], Meira, Renata [1].

News records of colleters in Chamaecrista (Leguminosae-Caesalpinioideae): structural diversity, secretion and functional role.

Chamaecrista Moench is a genus with a complex taxonomic history. In Brazil, this genus is predominantly found in open sunny areas such as “campos rupestres” and “cerrados”. Although colleters, secretory structures that occur in vegetative and/or reproductive shoot apices, have been described in embryos of three species of Chamaecrista, the presence of these structures has not been observed in vegetative and reproductive organs of Chamaecrista. This study describes the morphoanatomical structure of the colleters of 30 species that belong to four (sections Apoucouita, Absus, Chamaecrista and Xerocalyx) of the six sections recognized for Chamaecrista. The nature of chemical compounds of the secretion and ecological insights on the importance of the colleters are also provided. Standard light microscopy techniques and scanning electron microscopy for the morphoanatomical characterization were used. The nature of chemical compounds present in the secretory cells was tested by several histochemical tests. Control sections were performed simultaneously as required for each test. The following five different types of non-vascularized colleters were found in the species studied: club-shaped, short conic, long conic, euryform and petaloid. As observed in the ontogenetic study performed in Chamaecrista debilis, C. brachystachya and C. cytisoides, the colleters arise from the division of protodermal cells only, therefore they correspond to trichomes. Except C. dentata, C. glaziovii, and C. semaphora, all species presented colleters. Colleters were found in both leaf shoots and flower buds. They are present at the insertion of the stipules on the stem, on the adaxial side, and on the rachises between the leaflets and even around the extrafloral nectaries (when these are present). In flower buds, they are found at the base of the bracts and bracteoles, on the adaxial side. Club-shaped colleters were observed in sections Absus and Chamaecrista. The short conic type was observed in sections Apoucouita, Absus and Chamaecrista. In the section Xerocalyx only the long conic type was found. The euryform type was found in sections Absus and Chamaecrista. The histochemical tests carried out revealed the presence of total polysaccharides and pectins/mucilage. Lipophilic substances and phenolic compounds were not detected. Colleters are thought to play a role in protecting both young leaves and flowers against desiccation by secreting of a viscous mucilage secretion. The structural diversity and distribution of the colleters show the potential of such structures in phylogenetic approaches.
The authors wish to thank CPNq, CAPEs, FAPEMIG, and Floresta Escola for research grants and/or financial support.

Broader Impacts:

1 - Universidade Federal de Vicosa, Programa de Pos-Graduacao em Botanica/DBV, Vicosa, MG, 36570000
2 - Universidade Federal dos Vales do Jequitinhonha e Mucuri, campus JK, Departamento de Ciencias Biologicas
3 - Universidade do Estado da Bahia, campusVIII - Paulo Afonso, Programa de Pós-Graduação em Biodiversidade Vegetal

Keywords:
colleters
secretory structures
trichomes
mucilage secretion
Cassiinae
Taxonomy
campos rupestres
cerrados.

Presentation Type: Oral Paper:Papers for Sections
Session: 31
Location: Jasperwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 2:45 PM
Number: 31006
Abstract ID:927
Candidate for Awards:None