• Source: Fasciation

Fasciation (pronounced , from the Latin root meaning "band" or "stripe"), also known as cresting, is a relatively rare condition of abnormal growth in vascular plants in which the apical meristem (growing tip), which normally is concentrated around a single point and produces approximately cylindrical tissue, instead becomes elongated perpendicularly to the direction of growth, thus producing flattened, ribbon-like, crested (or "cristate"), or elaborately contorted tissue. Fasciation may also cause plant parts to increase in weight and volume in some instances. The phenomenon may occur in the stem, root, fruit, or flower head.
Some plants are grown and prized aesthetically for their development of fasciation. Any occurrence of fasciation has several possible causes, including hormonal, genetic, bacterial, fungal, viral and environmental causes.




Cause


Fasciation can be caused by hormonal imbalances in the meristematic cells of plants, which are cells where growth can occur. Fasciation can also be caused by random genetic mutation. Bacterial and viral infections can also cause fasciation. The bacterial phytopathogen Rhodococcus fascians has been demonstrated as one cause of fasciation, such as in sweet pea (Lathyrus odoratus) plants, and in lilies (Lilium longiflorum), but many fasciated plants have tested negative for the bacteria in studies, hence bacterial infection is not an exclusive causation.
Additional environmental factors that can cause fasciation include fungi, mite or insect attack and exposure to chemicals. General damage to a plant's growing tip and exposure to cold and frost can also cause fasciation. Some plants, such as peas and cockscomb Celosia, may inherit the trait.
Genetic fasciation is not contagious, but infectious fasciation can be spread from infected plants to others from contact with wounds on infected plants, and from water that carries the bacteria to other plants.




Occurrence


Although fasciation is rare overall, it has been observed in over 100 vascular plant families, including members of the genera Acer, Aloe, Acanthosicyos, Cannabis, Celosia, Cycas, Delphinium, Digitalis, Echinacea, Echinopsis, Euphorbia, Forsythia, Glycine max (specifically, soybean plants), Primula, Iochroma, Prunus, Salix, and many genera of the cactus family, Cactaceae. Cresting results in undulating folds instead of the typical "arms" found on mature saguaro cactus.
Some varieties of Celosia are raised especially for their dependably fasciated flower heads, for which they are called "cockscomb". The Japanese fantail willow (Salix sachalinensis 'Sekka') is another plant that is valued for its fasciations.




Prevention


Fasciation that is caused by bacteria can be controlled by not using fasciated plants and disposing of fasciated material. Avoiding injury to plant bases and keeping them dry can reduce the spread of bacteria. Avoidance of grafting fasciated plants and the pruning of fasciated matter can also reduce the spread of bacteria.




Examples



Fasciation
































































See also


Adventitiousness
Phyllody
Witch's broom




References






Further reading


White, Orland E. (1945). "The Biology of Fasciation". Journal of Heredity. 36: 11–22. doi:10.1093/oxfordjournals.jhered.a105409.
Crespi, M.; Messens, E.; Caplan, A.B.; Van Montagu, M.; Desomer, J. (1992). "Fasciation induction by the phytopathogen Rhodococcus fascians depends upon a linear plasmid encoding a cytokinin synthase gene". The EMBO Journal. 11 (3): 795–804. doi:10.1002/j.1460-2075.1992.tb05116.x. PMC 556518. PMID 1547783.
Nilsson, O.; Moritz, T.; Sundberg, B.; Sandberg, G.; Olsson, O. (1996). "Expression of the Agrobacterium rhizogenes rolC Gene in a Deciduous Forest Tree Alters Growth and Development and Leads to Stem Fasciation". Plant Physiology. 112 (2): 493–502. doi:10.1104/pp.112.2.493. PMC 157972. PMID 12226405.
Crespi, M.; Vereecke, D.; Temmerman, W.; Van Montagu, M.; Desomer, J. (1994). "The fas operon of Rhodococcus fascians encodes new genes required for efficient fasciation of host plants". Journal of Bacteriology. 176 (9): 2492–2501. doi:10.1128/jb.176.9.2492-2501.1994. hdl:1854/LU-322183. PMC 205384. PMID 8169198.




External links



"Definition of "Fasciation"". Merriam-Webster Dictionary. Retrieved July 6, 2012.

Kata Kunci Pencarian:

• Fasiasi
• Fasciation
• Celosia
• Syringa vulgaris
• Crest
• Saguaro
• Cockscomb (disambiguation)
• Fascination
• Petrosedum rupestre
• Teratology
• Echinacea