New Aspects of Secretory Structures in Five Alismataceae Species: Laticifers or Ducts?

Vitoria Silva Fabiano,Flávia Maria Leme,Jean David Varilla González,Rosani Do Carmo De Oliveira Arruda,João Pedro Silvério Pena Bento,Vali Joana Pott

doi:10.3390/plants10122694

Vitoria Silva Fabiano, Flávia Maria Leme + Show 4 more

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https://doi.org/10.3390/plants10122694

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Abstract

The secretory structures of Alismataceae have been described as secretory ducts, laticifer ducts, laticifer canals or schizogenous ducts. However, these terms are not found in the specialized literature, and ontogenetic analyses for the exact classification of these structures are missing. Accordingly, more studies regarding the secretory structures of Alismataceae are necessary to establish homology in the family or in the order. Thus, the aim of this study was to describe the anatomy, ontogeny, distribution in the organs and exudate composition of the secretory structures present in five Alismataceae species in order to determine whether the family has laticifers or secretory ducts. Samples of leaves, flowers and floral apices were processed for anatomical and histochemical analyses by light microscopy. The analysis indicated the presence of anastomosing secretory ducts in all species, occurring in both leaves and flowers. The exudate contains lipids, alkaloids, proteins and polysaccharides, including mucilage. The secretory duct structure, distribution and exudate composition suggest a defense role against herbivory and in wound sealing. The presence of secretory ducts in all species analyzed indicates a probable synapomorphy for the family.

Highlights

Alismataceae is a family consisting of floating to emergent aquatic or marsh herbs with a worldwide distribution [1]
Our objective was to study the structure, ontogeny, distribution in the organs and secretion composition of the secretory structures present in Echinodorus grandiflorus, H. tenellum, Hydrocleys nymphoides, Limnocharis flava and Sagittaria rhombifolia in order to determine whether the analyzed species have laticifers or secretory ducts
In E. grandiflorus, H. tenellum, H. nymphoides, L. flava and S. rhombifolia (Figure 1A–F), we found elongated secretory ducts consisting of an intercellular space or lumen lined with one layer of secretory cells, i.e., the epithelium

Summary

Introduction

Alismataceae is a family consisting of floating to emergent aquatic or marsh herbs with a worldwide distribution [1]. Limnocharitaceae was merged with Alismataceae to form one family comprising 17 genera [1,2,3,4] and ca. The family is known for including species with economic uses as food sources [6], ornamentals (aquarium plants) [6,7] and medicinals [6,7], as well as species for beekeeping [1,6]. The largest genera are Echinodorus and Sagittaria, both regularly used as aquarium and pond ornamental plants [1,6]. Ethnobotanical investigations and clinical trials indicate that E. grandiflorus leaves have anti-hypertensive, anti-inflammatory, diuretic, and anti-arthritic properties [7,10,11,12,13]

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