Pitchers Prevent Fungal Growth

plants shaped like a water pitcher hang from vines against a green background

Biological Strategy

Tropical pitcher plants

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Protect From Fungi

Fungi–which include molds and mushrooms, amongst others–play important roles in every ecosystem, but can also create diseases in plants and animals. Fungi can rapidly reproduce, so living systems must fend them off early to avoid their spread and potential, physical harm. Living systems use both physical and chemical strategies to protect from fungi, and must ensure that these strategies don’t harm the threatened living system itself. For example, a pumpkin’s skin has antifungal proteins to prevent fungal growth without harming the pumpkin itself.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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The pitchers of pitcher plants prevent fungal growth using napthoquinones.

“Nepenthes spp. are carnivorous plants that have developed insect
capturing traps, evolved by specific modification of the leaf
tips, and are able to utilize insect degradation products as
nutritional precursors. A chitin-induced antifungal ability,
based on the production and secretion to the trap liquid of droserone
and 5-O-methyldroserone, is described here. Such specific secretion
uniquely occurred when chitin injection was used as the
eliciting agent and probably reflects a certain kind of defence
mechanism that has been evolved for protecting the carnivory-based
provision of nutritional precursors. The pitcher liquid
containing droserone and 5-O-methyldroserone at 3:1 or
4:1 molar ratio, as well as the purified naphthoquinones,
exerted an antifungal effect on a wide range of plant and
human fungal pathogens. When tested against Candida
and Aspergillus spp., the concentrations required for
achieving inhibitory and fungicidal effects were significantly
lower than those causing cytotoxicity in cells of the human
embryonic cell line, 293T. These naturally secreted
1,4-naphthoquinone derivatives, that are assumed to act via
semiquinone enhancement of free radical production, may offer
a new lead to develop alternative antifungal drugs with
reduced selectable pressure for potentially evolved resistance.” (Eilenberg et al. 2010:911)

Note: According to the paper, the exact mode of function of napthoquinones is unknown.

http://www.sciencedaily.com/releases/2010/02/100218150652.htm
http://jxb.oxfordjournals.org/cgi/content/abstract/erp359

Last Updated August 18, 2016

References

Journal article

Induced production of antifungal naphthoquinones in the pitchers of the carnivorous plant Nepenthes khasiana

Journal of Experimental Botany | 17/12/2009 | H. Eilenberg, S. Pnini-Cohen, Y. Rahamim, E. Sionov, E. Segal, S. Carmeli, A. Zilberstein

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Reference

From carnivorous plants to the medicine cabinet? Anti-fungal agents in pitcher plants investigated

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