Pollinators, natural

Weiss, M. R. (1991). Floral colour changes as cues for pollinators. Nature 354 227-229. 

The tropical orchid Vanilla planifolia is pollinated naturally by the tiny Meli-pone bee, native to Mexico. In areas where the bee does not live, the orchid must be pollinated artificially by humans. 

The function of the essential oil in the plant is not fully understood. Microscopic examination of plant parts that contain the oil sacs readily shows their presence. The odors of flowers are said to act as attractants for insects involved in pollination and thus may aid in preservation and natural selection. Essential oils are almost always bacteriostats and often bacteriocides. Many components of essential oils are chemically active and thus could participate readily in metaboHc reactions. They are sources of plant metaboHc energy, although some chemists have referred to them as waste products of plant metaboHsm. Exudates, which contain essential oils, eg, balsams and resins, act as protective seals against disease or parasites, prevent loss of sap, and are formed readily when the tree tmnks are damaged. 

In the natural world, carotenoid oxidation products are important mediators presenting different properties. Volatile carotenoid-derived compounds such as noriso-prenoids are well known for their aroma properties. Examples include the cyclic norisoprenoid P-ionone and the non-cyclic pseudoionone or Neral. Carotenoid oxidation products are also important bioactive mediators for plant development, the best-known example being abscisic acid. Apo-carotenoids act as visual and volatile signals to attract pollination and seed dispersal agents in the same way as carotenoids do, but they are also plant defense factors and signaling molecules for the regulation of plant architecture. 

The two types of wood differ, however, in their nature and structure. The main structural characteristic of the hardwoods (which are botanically known as angiosperms, plants that flower to pollinate for seed reproduction) is that in their trunks or branches, the volume of wood taken up by dead cells, varies greatly, although it makes up an average of about 50% of the total volume. In softwoods (from the botanical group gymnosperms, which do not have flowers but use cones for seed reproduction) the dead cells are much more elongated and fibrous than in hardwoods, and the volume taken up by dead cells may represent over 90% of the total volume of the wood. 

Camelina sativa, a rare and unexploited crop plant Camelina sativa is grown as a crop plant only in Finland and Ireland. Because it is a self-pollinating plant the risk of inadvertently transferring the new trait to naturally occurring plant relatives in the environment is low. Camelina sativa has not been extensively used in plant breeding, which means that there are only few varieties of the plant... 

Nabhan, G. P., and S. L. Buchman. "Services Provided by Pollinators." In Nature s Services, edited by G. C. Daily, 133-150. Washington Island Press, 1997. 

GM crops have been introduced rapidly, without extensive testing, on the grounds that they are similar to nonengineered crops. But the process involves creating gene combinations that could not have occurred naturally. Once released into the environment, genes that "escape" from the GM parent plant, via soil bacteria or cross-pollination, will be impossible to retrieve. Once incorporated into wild plants, we can only surmise what the outcome might be. 

Wind has the obvious effect of damaging branches. Less obvious is the fact that pollinating insects cannot visit blossoms in blustery weather, and this will affect the size of the harvest. Some gardens are naturally sheltered. If not, thought needs to be given to creating shelters against the wind. 

Schnee C, Koellner TG, Held M, Turlings TCJ, Gershenzon J, Degenhardt J (2006) The products of a single maize sesquiterpene synthase form a volatile defense signal that attracts natural enemies of maize herbivores. Proc Natl Acad Sci USA 103 1129-1134 Pichersky E, Gershenzon J (2002) The formation and function of plant volatUes perfumes for pollinator attraction and defense. Curr Opin Plant Biol 5 237-243... 

Chalcones (l,3-diaryl-2-propen-l-ones) are open-chain fiavonoids that are widely biosynthesized in plants. They are important for the pigmentation of flowers and, hence act as attractants to the pollinators. As fiavonoids, chalcones also play an important role in defending against pathogens and insects. A review of the literature concerning the evaluation of natural chalcones from medicinal plants reveals that many studies into their antimicrobial and antiviral activities have been carried out in recent years. Some of these compounds were isolated by bioassay-guided fractionation, after previously detecting activity on the part of the plants. 

Under these competitive conditions for space and resources, tropical plants have evolved a variety of signaling secondary metabolites. Some serve to attract pollinator insects, other ones as a defense against grazers and parasites. This makes the tropical land a center of high natural product diversity. 

Natural scents are exclusive products, used for the most highly-priced perfijmes. The largest market of perfumes - particularly in the poor developing countries - is based on synthetic materials. Natural scents are mostly derived from flower plants, evolved to be recognized by pollinating insects. The orchids (flower plants in the monocotyledonous family Orchidaceae, which make about 10% of all flower plants) are highly rated for scents, particularly the woody scent afforded by a sesquiterpenoid, caryophyll-5-en-2a-ol. 

One of the best-established functions of anthocyanins is in the production of flower color and the provision of colors attractive to plant pollinators. Considerable effort has been made to give explanations for the color variations expressed by anthocyanins in plants. Various factors including concentration and nature of the anthocyanidin, anthocyanidin equilibrium forms, the extent of anthocyanin glycosidation and acylation, the nature and concentration of copigmentation, metal complexes, intra- and intermolecular association mechanisms, and influence of external factors like pH, salts, etc. have been found to have impact on anthocyanin colors. ... 

Peloquin, S. J., Gabert, A. C., Ortiz, R. (1996). Nature of pollinator effect in potato Solanum tuberosum L.) haploid production. Annals of Botany, 77, 539-542. 

Extrafloral nectaries include a wide range of nectar-excreting structures, which are distinguished from their floral counterparts by the fact that they are not involved in pollination. Extrafloral nectar is typically dominated by sucrose and its hexose components glucose and fructose. The fact that these common sugars are acceptable to the majority of insects, combined with the exposed nature of extrafloral nectaries, makes them suitable food sources for abroad range of insects. Compared with floral nectar, extrafloral nectar often has increased fructose and glucose levels (Tanowitz... 

Proctor, M., Yeo, P. and Lack, A. (1996). The Natural History of Pollination. Portland, OR Timber Press. 

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