phytochrome


Also found in: Dictionary, Encyclopedia, Wikipedia.
Related to phytochrome: Cryptochrome
Phytochromeclick for a larger image
Fig. 252 Phytochrome . The photoconversion of the two forms.

phytochrome

a type of plant pigment that occurs in two forms, P660 (Pr) which absorbs red light (600–700 nm) and P725 (Pfr) which absorbs far-red light (700–760 nm). P72 5 is biologically active in that it stimulates enzymic reactions, whereas P660 is biologically inert. The conversion of one form into the other occurs simultaneously. See Fig. 252 .

Daylight contains a mixture of red and far-red light, with a predominance of red light. During the day the proportion of P725 builds up relative to P660, whereas during the night there is a gradual conversion of P725 to P660. Thus phytochrome provides the plant with a method of detecting day and night, with P72 5 predominant when it is day, and P660 predominant when it is night. This mechanism is the basis of PHOTOPERIODISM.

References in periodicals archive ?
The researchers observed several characteristic structural changes in the light-sensitive segment of a phytochrome molecule from cyanobacteria and created a model that shows the light-triggered conversion steps.
stans also presents phytochrome B (PhyB), which has been associated with the detection of forest gaps through changes in the R:FR ratio (Smith, 1995).
Cryptochrome, phytochrome, and anthocyanin production.
The explanation for the shorter seedling length in the dark is the permanence of phytochrome A throughout seedling development, which inhibits etiolation, a phenomenon that only occurs in the presence of phytochrome B (Carvalho & Peres, 2013).
Previous studies have confirmed that the seeds depend on phytochrome, perceiving the surrounding environment and respond through the optical signal pathway (Dooley et al., 2013).
Abe, "Genetic redundancy in soybean photoresponses associated with duplication of the phytochrome A gene," Genetics, vol.
There are reports indicating the role of light detector Phytochrome B and HDA6 in regulating light-controlled chromatin of Nuclear Organization Regions (NORs) [23].
Inflorescence stems of Arabidopsis thaliana bend away from neighbours through a response controlled by phytochrome B
Phylogeny of the parasitic family Orobanchaceae inferred from phytochrome A.
Control of mitosis by phytochrome and a blue-light receptor in fern spores.