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Abstract To survive in the nutrient-poor habitats, carnivorous plants capture small organisms comprising complex substances not suitable for immediate reuse. The traps of carnivorous plants, which are analogous to the digestive systems of animals, are equipped with mechanisms for the breakdown and absorption of nutrients. Such capabilities have been acquired convergently over the past tens of millions of years in multiple angiosperm lineages by modifying plant-specific organs including leaves. The epidermis of carnivorous trap leaves bears groups of specialized cells called glands, which acquire substances from their prey via digestion and absorption. The digestive glands of carnivorous plants secrete mucilage, pitcher fluids, acids, and proteins, including digestive enzymes. The same (or morphologically distinct) glands then absorb the released compounds via various membrane transport proteins or endocytosis. Thus, these glands function in a manner similar to animal cells that are physiologically important in the digestive system, such as the parietal cells of the stomach and intestinal epithelial cells. Yet, carnivorous plants are equipped with strategies that deal with or incorporate plant-specific features, such as cell walls, epidermal cuticles, and phytohormones. In this review, we provide a systematic perspective on the digestive and absorptive capacity of convergently evolved carnivorous plants, with an emphasis on the forms and functions of glands.
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The curious case of stomach diverticula in Epiphanes clavulata (Rotifera: Monogononta)
Abstract Rotifers are aquatic micrometazoans with a variety of feeding styles and dietary preferences. The morphology of their digestive tracts is well known, but there are few details on the structure of any organs. Here we use transmission electron microscopy and fluorescence microscopy to investigate the stomach of Epiphanes clavulata, which is unusual in its possession of 6 diverticula that are absent in other taxa. We focus on this region to determine whether these diverticula are exocrine and potentially homologous to gastric glands, which are the main digestive organs of rotifers, but absent in this species. Results reveal that the stomach is cellular and that all cells are ciliated, nucleated, and contain abundant phagosomes and lipid droplets. The stomach appears to play 2 major roles: intracellular digestion as evidenced by the presence of caveolae and phagosomes and lipid biogenesis and storage as evidenced by accumulation of large lipid droplets. The 6 diverticula are syncytial extensions of individual stomach cells and contain 1 to several nuclei, many mitochondria, autophagic vesicles, ribosomes, and inclusion bodies. The rough endoplasmic reticulum is abundant and associated with small electron-dense droplets enclosed in a phospholipid monolayer, suggesting they contain lipids; however, the absence of discernable staining with a neutral lipid dye confounds a more specific identification of their contents. There is no evidence to suggest the diverticula are homologous to gastric glands nor do they play an obvious role in digestion; instead, they may function as a secondary site of lipid biogenesis and storage.
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- PAR ID:
- 10675257
- Editor(s):
- Huang, Zu-Shi
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Current Zoology
- ISSN:
- 1674-5507
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/cz/zoaf032
