Details

Autor(en) / Beteiligte

• Lev-Yadun, Simcha

Titel

Defensive functions of white coloration in coastal and dune plants

Ist Teil von

• Israel journal of plant sciences, 2006-01, Vol.54 (4), p.317-325

Ort / Verlag

Netherlands: BRILL

Erscheinungsjahr

2006

Beschreibungen/Notizen

• Trichomes are known to have many functions, including protecting plants from excess sunlight, improving water economy, salt secretion, defense from herbivores, and signaling to animals. Additional anti-herbivore functions of trichomes, especially in coastal and desert habitats, are reviewed and proposed. Many sand-dune and sandy shore plants are white, whitish, or silver-colored because of white trichomes, because of sticky glandular trichomes to which sand grains and clay adhere, or because of light-colored waxes. The common explanation for this coloration is that it protects from irradiation, and that in addition, the glued sand defends them from abrasion by moving sand. This coloration was also proposed to camouflage the plants from herbivores. Similar coloration in animals that live in white, snow-covered habitats or light-colored sand or other soil substrates is commonly referred to as camouflage, and the same logic may also apply to plants. It has also been proposed that white plant surfaces undermine the camouflage of herbivorous insects that have other colors and expose them to predation. Three novel defensive mechanisms are proposed here: (1) because dust is a strong insect repellent and is lethal to insects, attached soil particles (especially clays) may defend plants with sticky glandular trichomes from insect herbivory; (2) in dicotyledonous plants that have sticky glandular trichomes, the attached sand may defend from herbivory by mammals by causing teeth wear as do phytoliths (silica bodies) of grasses; and (3) white coloration of leaves and branches may mimic fungal infestation. Direct experimental data for the functionality of these defensive mechanisms are missing for many of the old and all new hypotheses, but there are many indirect supporting indications.