Research on nutrient acquisition by different species of carnivorous plants

Interactive phylogenetic tree of carnivorous plants

You can click on the individual species to view detailed photographs of these plants in their natural habitat and to get more information about each species (it will open in a new browser window).

A quantification of the utilization of insect nitrogen of different carnivorous plants

The table shows a comparison of different carnivorous plants with respect to the amount of plant nitrogen obtained from insect nitrogen. The values have been calculated by using the natural abundance of stable nitrogen isotopes. Data have been collected from plants growing all over the world, i.e. Nepenthes (Australia), Cephalotus (Australia), and several species of Australian Drosera, Darlingtonia (USA), Dionaea (USA), and Heliamphora and Brocchinia (Venezuela).

capturing organ genus growth form insect N per total N (%) n
sticky leaves Drosera rosette 19.6 E11 3 populations
vine 52.9 E 24 4 species
erect low 48.5 E 11 3 species
erect high 53.7 E 10 3 species
pitcher Cephalotus rosette 26.1 E 6 3 sites
Nepenthes vine 61.5 E 7 5 plants
Darlingtonia rhizome 76.4 E 9 5 plants
Heliamphora rhizome 79.3 E 4 5 plants
Brocchinia erect rosette 59.8 E 2 3 sites
suction trap Polypompholyx   20.1 E 10 2 plants
moving leaf trap Dionaea rosette 80.4 E 4 3 sites /30 plants

Some photos of carnivorous plants in the experiments or in the field

In this experiment, growth of Drosera rotundifolia was measured at different rates of insect capture. Leaves were marked to estimate the life spans of each leaf and calculate leaf turnover.
 Drosera rotundifolia in a growth experiment

a pitcher of Nepenthes mirabilis
Nepenthes mirabilis from Australia is an ideal plant to study the change of nitrogen source from soil to insects. It grows long branches with pitchers attached to phyllodes. The youngest pitchers are still active and thus receive mainly insect nitrogen, whereas older leaves and old pitchers are supported more and more by soil nitrogen.
a vining branch of Nepenthes mirabilis

Darlingtonia
Darlingtonia (left), the Californian pitcher plant. It grows its pichers from a rhizome and it has noadditional leaf organs. Sometimes a frog lives in the pitchers of Cephalotus (right), eventually stealing the plant's prey. Cephalotus has its pitchers close to the ground and grows normal leaves in a rosette in additon to pitchers.
a frog in the pitcher of Cephalotus

Dionaea has a unique trapping mechanism consisting of two moving leaf lobes. The growth of Dionaea in nature is restricted to very special habitats characterized by regular bush fires to keep competing vegetation low (left).

a Dionaea plant with big traps
During succession after fires, Dionaea is rapidly overgrown by competing grasses (right).

Dionaea is being overgrown by grasses

Roridula (left), growing in South Africa, is not a real carnivorous plant. Moreover the bugs on its leaves eat the captured insects and the plant utilizes the nitrogen from the feces of the bug.

The "Mouth" of Nepenthes - Expression of Transporters for Ammonium, Amino Acids, and Peptides in Pitchers of Nepenthes alata
Waltraud Schulze, Wolf Frommer, and John Ward
ZMBP, Universität Tübingen
Carnivorous plants, such as Nepenthes, are adapted to a nutrient poor environment and supplement their nitrogen budget by the capture and digestion of insects. The contribution of insect nitrogen to total plant nitrogen can be up to 70% of the plant's nitrogen content. 
At the same time the plant invests a substantial amount of resources into the development of special trapping organs and digestive system.
The uptake of nutrients from the pitcher fluid and the transport to other plant organs are important steps in the nitrogen acquisition from pitchers. However, very little is known about the molecular mechanisms involved.
in-situ-hybridization

 

Three genes encoding transporters for either ammonium (NaAMT1), amino acids (NaAAP1) or peptides (NaPTR1) were cloned from Nepenthes pitchers. The expression of these transporters in pitchers of different ages, with and without prey were analyzed by northern blots and in-situ hybridization.

Pitchers absorb nitrogen in the form of ammonium, amino acids, and possibly peptides. Transporters for all of these nitrogenous compounds are expressed in pitchers, the expression of NaAMT1 and NaPTR1 was found to be pitcher specific. Expression of these transporters increased upon the presence of prey in the pitchers, but no increase in expression was observed upon feeding the pitchers with the substrates of the transporters. Expression of NaAMT1 increased with the time a pitcher was open (i.e. with age), the expression of NaPTR1 doubled upon pitcher opening, and the expression of NaAAP1 was highest in closed pitchers. In-situ hybridization (see figure at left) demonstrated a differential expression of the transporters within the pitcher. NaAMT1 was expressed in the head cells of digestive glands of the inner epidermis (a), NaAAP1 in the sclerenchymatic bundle sheath cells (b), and NaPTR1 is expressed in phloem (c).

A function of NaAMT1 in uptake of ammonium from the pitcher fluid, of NaAAP1 in transport of amino acids into the vascular tissue, and of NaPTR1 in phloem loading with peptides is discussed. This indicates an efficient nitrogen concentration mechanism allowing for maximum nitrogen export to sink organs.