Journal
AMERICAN JOURNAL OF BOTANY
Volume 102, Issue 9, Pages 1413-1421Publisher
BOTANICAL SOC AMER INC
DOI: 10.3732/ajb.1500317
Keywords
apoplasmic tracing; cypsela; Emilia fosbergii; mucilaginous trichome; plant establishment; seed dispersion; seed imbibition
Categories
Funding
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) from Brazil
Ask authors/readers for more resources
PREMISE OF THE STUDY: Several angiosperm families have myxodiaspory, such as the Asteraceae in which cypselae are frequently wind-dispersed. The roles of mucilage in cypselae remain misunderstood, and the route of water uptake from substrate to embryo remains unknown. In this work, we analyze the fruits of Emilia fosbergii aiming to clarify how the water is absorbed and how the structure of the pericarp can be related to the processes of diaspore adhesion and seed imbibition. METHODS: The anatomy and ultrastructure of the cypselae of Emilia fosbergii were analyzed with histochemical tests and light, scanning and transmission electron microscopy. We assessed the roles of mucilage in seed imbibition using apoplasmic tracing with Lucifer yellow and epifluorescence microscopy and in adhesion with a sand assay. KEY RESULTS: We describe structural and ultrastructural aspects of the exocarpic cells, especially the mucilaginous twin hairs. Lucifer yellow was absorbed only by the twin hairs, the cells where water primarily enters the seed during seed imbibition. In the sand assay, the mucilage was adhesive. CONCLUSIONS: The twin hairs on the surface of the cypselae can play a dual role in the establishment of new plants of this species. First, these trichomes constitute the main passage for water intake, which is essential for seed imbibition and germination, and after imbibition, they release mucilage that can adhere the diaspore. Therefore, the presence of myxocarpy in Asteraceae could be important in anemochoric species to avoid secondary dispersal.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available