Plants benefit in many ways from animals; e.g., animals play a role as pollinators and as dispersers of fruits

1. Sahebe Shahedi Reyhane Dehghanzad
Nasim Arshadi

2. Plants benefit in many ways from animals; e.g.,
animals play a role as pollinators and as dispersers
of fruits. However, animals may also contribute
to a plant’s nutrition by being caught and
digested. This phenomenon of carnivory has
fascinated the scientific community ever since
Darwin drew attention to it (Darwin, 1875(.
Although carnivorous plants can obtain water
and at least some minerals from the soil, they
also extract nutrients from captured animals.
abstract

3. Carnivorous plants attract their victims by means of
scent, colouration and nectar (Lloyd, 1942(.
They are able to trap and retain their victims,
kill them, and digest their soft tissues, and take
up at least part of their contents (Juniper et al.,
1989;Lloyd, 1942(.

4. This whole process is
achieved by highly specialized leaves, which have
been transformed into various types of traps.
Therefore, the leaves may take over functions
that are usually restricted to the roots of noncarnivorous
plants. The general features of carnivorous
plants have been reviewed in detail by
Juniper et al. (1989(.

5. Five types of traps can be distinguished:
1(Adhesive traps produce sticky mucilage that is
able to glue little animals to the leaves. Such
‘fly-paper’ traps may actively roll over their
victims (Drosera, Pinguicula( or they remain
motionless (Byblis, Drosophyllum(.

6. 2(In steel traps, the leaf forms two lobes, which
snap around animals that touch sensitive trigger
hairs on the surface of the lobes (Dionaea,
Aldrovanda(.
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7. 3(In pitcher traps, leaves have been transformed
to a pit that contains a pool of digestive
enzymes (Darlingtonia, Nepenthes, Sarracenia,
Cephalotus, Heliamphora(. Animals are
attracted towards the rim, and glide into the
pit along the slippery inner surface, which prohibits
escape.
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8. 4(Even more sophisticated are the eel traps that
attract prey through a system of claw-like cells
and inward-pointing hairs into a bulb where it
is digested and absorbed (Genlisea(.
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9. 5(The suction traps have the form of bladders
that arise from leaves. Little animals that
touch sensitive hairs near the entrance are
sucked into the bladder through a trap door,
due to the lower hydrostatic pressure inside,
and are then digested (Utricularia(.

10. Plants usually absorb nutrients such as nitrogen,
phosphorus,
potassium, and other minerals from the soil via their roots.
However, carnivorous plants growing in nutrient-poor soils
obtain nutrients from trapped insects using special organs
to
capture and digest them.

11. Nepenthes, which is commonly known as the tropical
pitcher plant, includes more than 100 species. Within this
genus, the greatest species diversity is in Borneo and
Sumatra.
Nepenthes species are widely distributed in the tropics,
such as
India, Sri Lanka, Australia, New Caledonia, Madagascar,
and
the Seychelles. The ‘pitcher’ bud forms at the end of the
leaf
and gradually expands into a pot-shaped trap.

12. The most abundant
constituent of pitcher fluid is “nepenthesin”, an enzyme that
shows stable activity up to 60 °C and appears to cleave
peptides
preferentially at the carboxyl side of aspartic acid residues.
Athauda et al. purified the enzymes nepenthesins I and II
from
Nepenthes distillatoria and the partial sequences were
determined. They cloned the cDNAs and deduced the
complete
amino acid sequences of the enzymes from Nepenthes
.gracilis

13. The addition of chitin into closed pitchers of
Nepenthes khasiana induced the synthesis of new proteins,
.including those with chitinase activity, in the pitcher fluid

14. Therefore, the addition of chitin or chitin
oligosaccharides to
plants has often been used to investigate the plant
defense
system against fungal disease. Plants have
pathogen recognition
molecules known as pattern recognition receptors
(PRRs(

15. The
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