RippedTorn
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Purple phloem:
Anthocyanin is derived from another pigment, “anthocyanidin,” that is comprised of a sugar-like molecule. The accumulation of anthocyanin occurs when the plant is not capable of translocating sugars to different plant organs.
The purple coloration phenomenon takes place when photosynthetic tissues of the plant are acting as sources of sugars, while the sinks are not utilizing sugars as fast as the sugars are being produced. When this happens, the flow of sugars within the plant is disrupted and the sugars can accumulate in various areas of the plants, causing the purple coloration. This could be a result of several different factors:
Environment-by-genetic interaction: There may be a specific hybrid response to environmental conditions, such as cool nights followed by sunny days, causing a buildup of sugars. The presence or absence of the genes associated with the production of anthocyanin is specific to certain hybrids.
Restricted root development: Restrictions in root growth, which may be due to several different factors -- such as drought stress, saturated soils, soil compaction, cool temperatures, herbicide injury, insect feeding, or shallow planting -- may cause a reduced demand for sugars, thus increasing purple coloration. This situation is more likely to occur early in the vegetative stages.
Poor bud development: Bud development may be impaired by any number of factors causing a disruption in the demand for sugars from photosynthesis.
Regardless of the specific factor that causes anthocyanin accumulation, the production of the purple coloration is associated with some kind of restriction in the utilization of carbohydrates produced during photosynthesis.
Purple Xylem
Tracheary elements are dead cells and to block them, plants uses tylose vessel element “stoppers” which also help control winter functioning of vessels. Vascular occlusion in xylem conduits is a common response to environmental stresses, and plant species are recognized as primarily tylose-forming or gel-forming. Gels (gums) are vascular plugs with a fibrillose structure formed by material secreted from adjacent xylem parenchyma. Although the precise chemical composition is not yet known, pectin, hemicellulose, and phenolics appear to be basic components of gels.
Anthocyanin is derived from another pigment, “anthocyanidin,” that is comprised of a sugar-like molecule. The accumulation of anthocyanin occurs when the plant is not capable of translocating sugars to different plant organs.
The purple coloration phenomenon takes place when photosynthetic tissues of the plant are acting as sources of sugars, while the sinks are not utilizing sugars as fast as the sugars are being produced. When this happens, the flow of sugars within the plant is disrupted and the sugars can accumulate in various areas of the plants, causing the purple coloration. This could be a result of several different factors:
Environment-by-genetic interaction: There may be a specific hybrid response to environmental conditions, such as cool nights followed by sunny days, causing a buildup of sugars. The presence or absence of the genes associated with the production of anthocyanin is specific to certain hybrids.
Restricted root development: Restrictions in root growth, which may be due to several different factors -- such as drought stress, saturated soils, soil compaction, cool temperatures, herbicide injury, insect feeding, or shallow planting -- may cause a reduced demand for sugars, thus increasing purple coloration. This situation is more likely to occur early in the vegetative stages.
Poor bud development: Bud development may be impaired by any number of factors causing a disruption in the demand for sugars from photosynthesis.
Regardless of the specific factor that causes anthocyanin accumulation, the production of the purple coloration is associated with some kind of restriction in the utilization of carbohydrates produced during photosynthesis.
Purple Xylem
Tracheary elements are dead cells and to block them, plants uses tylose vessel element “stoppers” which also help control winter functioning of vessels. Vascular occlusion in xylem conduits is a common response to environmental stresses, and plant species are recognized as primarily tylose-forming or gel-forming. Gels (gums) are vascular plugs with a fibrillose structure formed by material secreted from adjacent xylem parenchyma. Although the precise chemical composition is not yet known, pectin, hemicellulose, and phenolics appear to be basic components of gels.
