Pearl bodies are small (0.5 - 3.0 mm), lustrous, pearl-like food bodies produced from the epidermis of leaves, petioles and shoots of certain plants. They are rich in

lipids Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins Vitamin A, A, Vitamin D, D, Vitamin E, E and Vitamin K, K), monoglycerides, diglycerides, phospholipids, and others. The fu ...

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...

and

carbohydrates A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ma ...

, and are sought after by various arthropods and ants, that carry out vigorous protection of the plant against herbivores, thus functioning as a biotic defence. They are globose or club-shaped on short peduncles, easily detached from the plant, and are food sources in the same sense as

Beltian bodies A Beltian body is a detachable tip found on the pinnules of some species of ''Acacia'' and closely related genera. Beltian bodies, named after Thomas Belt, are rich in lipids, sugars and proteins and often red in colour. They are believed to have ...

, Müllerian bodies, Beccarian bodies, coccid secretions and

nectar Nectar is a viscous, sugar-rich liquid produced by Plant, plants in glands called nectaries, either within the flowers with which it attracts pollination, pollinating animals, or by extrafloral nectaries, which provide a nutrient source to an ...

ies. They occur in at least 19 plant families (1982) with tropical and subtropical distribution. Cells or tissues that offer food rewards to arthropods are commonplace in the plant world and are an important way of establishing symbiotic relationships. Ants collect these energy-rich bodies (27.8 kJ/g dry weight) and carry them into their nests. Removal of these bodies appears to stimulate the formation of new ones in the same place. The simultaneous presence of pearl bodies, ant

domatia A domatium (plural: domatia, from the Latin "domus", meaning home) is a tiny chamber that houses arthropods, produced by a plant. Ideally domatia differ from galls in that they are produced by the plant rather than being induced by their inhabi ...

and

extrafloral nectaries Nectar is a viscous, sugar-rich liquid produced by plants in glands called nectaries, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, ...

, suggest a facultative plant-ant mutualism. Early researchers dubbed these bodies 'perldrüsen' ( Meyen 1837), 'pärlharen' (Nils Holmgren 1911) and 'perlules' (Kazimierz Stefan Rouppert 1926). Pearl bodies appear to be the primary, and possibly the only nutrient for ants inhabiting Central American

myrmecophytes Myrmecophytes (; literally "ant-plant") are plants that live in a Mutualism (biology), mutualistic association with a colony of ants. There are over 100 different genera of myrmecophytes. These plants possess structural adaptations in the form o ...

. Phytophagous mites such as ''Tetranychus kanzawai'' have been observed feeding on pearl bodies produced by ''

Cayratia japonica ''Causonis japonica'' (also known by its synonym '' Cayratia japonica'' and common names bushkiller, yabu garashi and Japanese cayratia herb) is a vine plant in the grape family, Vitaceae. It is the type species of its genus and is native to tro ...

'' of the family

Vitaceae The Vitaceae are a family of flowering plants, with 14 genera and around 910 known species, including common plants such as Vitis, grapevines (''Vitis'' spp.) and Parthenocissus quinquefolia, Virginia creeper (''Parthenocissus quinquefolia''). Th ...

, a family in which pearl bodies are common. It also appears possible that the predatory mite '' Euseius sojaensis'' uses the pearl bodies as an alternative food source. Pearl bodies are important in the association between the ant species '' Pheidole bicornis'' and various '' Piper'' species that have spaces between the leaf petiole and stem suitable for use as ant domatia. Some ''Piper'' species have stems hollowed out by the ants, while others have naturally hollow stems. These tunnels are 3 – 4 mm in diameter, and, when the ants are in residence, numerous pearl bodies grow from the adaxial surfaces of the petioles, and from the tunnel walls. A study by Deborah K Letourneau in 1983 found that the ants were so sated by the plant's pearl bodies that more than half the insect eggs they encountered while patrolling were dropped to the ground. In '' Mallotus japonicus'' extrafloral nectaries and pearl bodies function as a biotic defence, while a second line of defence is made up

trichomes Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

and pellucid dots containing toxic secondary

metabolites In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

.
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External links

"The importance of petiole structure on inhabitability by ants"

"Annals of Natural History"

Gallery

File: Cissus quadrangularus var. quadrangularis 1DS-II 6424.jpg, '' Cissus quadrangularis'', young growth showing several pearl bodies. File:Cissus quadrangularus var. quadrangularis 1DS-II 6422-01.jpg, '' Cissus quadrangularis'', young stem with several pearl bodies. File:Hibiscus nigricaulis 1DS-II 1-6284.jpg, ''Hibiscus nigricaulis'', node with base of flower, showing pearl bodies on stem and epicalyx. File:Pavonia transvaalensis 1DS-II 1-2987.jpg, ''Pavonia transvaalensis'', several pearl bodies mainly on epicalyx.

References

{{reflist Insect ecology Plant physiology Plant morphology Herbivory Antipredator adaptations

See also

External links

Gallery

References