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types of algae (Le.: diatoms, dinoflagellates, etc.) based on the green algal/higher plant data,
even when measured under identical conditions, is certainly open to criticism. There are
presently several major obstacles to broad interpretation of fluorescence yield data.
The mechanism of photochemical fluorescence quenching, that is, the regulation of
fluorescence yield by the redox state of the primary quinone acceptor of PS II, is probably
identical among all oxygen-evolving plants and algae. Although fluorescence quenching
studies have not been applied systematically to all algal classes, it is widely accepted that the
proteins, pigments, and electron transport components of the PS II (and PS I) reaction center
complex have been highly conserved throughout evolution (Thornber, 1975; Bryant, 1986).
Since the components involved in regulating qp are all localized in the PS II reaction center,
their function in regulating qp is probably also conserved. Similarly, the mechanism of
photoinhibitory damage to PS II may be conserved among the algae. Studies in several algal
classes have demonstrated a loss of variable fluorescence coincident with a decline in
photosynthetic capacity (Neale, 1987).
In contrast, there is no reason to expect that any of the processes contributing to nonphotochemical fluorescence quenching (with the exception of photoinhibition) are conserved
among the algae. The reaction(s) of non-photochemical quenching is thought to occur in the
light-harvesting antenna complexes, and these complexes exhibit considerable diversity among
the algal classes (Owens, 1988; Anderson and Barrett, 1986). This is not to say that
formation of a trans-thylakoid dpH, regulation of functional antenna size through light state
transitions, and photoinhibition do not occur in all algal classes. Nor should we expect that
non-photochemical quenching will be absent in other algal classes. Dealing with variable light
intensities is a common problem for all photosynthetic organisms. Because the nonphotochemical quenching processes are components of an overall photosynthetic process that
has evolved in a common environment, it is likely that non-photochemical quenching occurs
in some form in all algal classes. However, they may differ in their mechanistic contributions
to fluorescence quenching.
Regulation of
types of algae (Le.: diatoms, dinoflagellates, etc.) based on the green algal/higher plant data,
even when measured under identical conditions, is certainly open to criticism. There are
presently several major obstacles to broad interpretation of fluorescence yield data.
The mechanism of photochemical fluorescence quenching, that is, the regulation of
fluorescence yield by the redox state of the primary quinone acceptor of PS II, is probably
identical among all oxygen-evolving plants and algae. Although fluorescence quenching
studies have not been applied systematically to all algal classes, it is widely accepted that the
proteins, pigments, and electron transport components of the PS II (and PS I) reaction center
complex have been highly conserved throughout evolution (Thornber, 1975; Bryant, 1986).
Since the components involved in regulating qp are all localized in the PS II reaction center,
their function in regulating qp is probably also conserved. Similarly, the mechanism of
photoinhibitory damage to PS II may be conserved among the algae. Studies in several algal
classes have demonstrated a loss of variable fluorescence coincident with a decline in
photosynthetic capacity (Neale, 1987).
In contrast, there is no reason to expect that any of the processes contributing to nonphotochemical fluorescence quenching (with the exception of photoinhibition) are conserved
among the algae. The reaction(s) of non-photochemical quenching is thought to occur in the
light-harvesting antenna complexes, and these complexes exhibit considerable diversity among
the algal classes (Owens, 1988; Anderson and Barrett, 1986). This is not to say that
formation of a trans-thylakoid dpH, regulation of functional antenna size through light state
transitions, and photoinhibition do not occur in all algal classes. Nor should we expect that
non-photochemical quenching will be absent in other algal classes. Dealing with variable light
intensities is a common problem for all photosynthetic organisms. Because the nonphotochemical quenching processes are components of an overall photosynthetic process that
has evolved in a common environment, it is likely that non-photochemical quenching occurs
in some form in all algal classes. However, they may differ in their mechanistic contributions
to fluorescence quenching.
Regulation of