Why is pigment important

They cannot continue to stay in that energy level, as it is not the state of stability for these electrons, so they must dissipate this energy and come back to their stable energy level. During photosynthesis these high-energy electrons transfer their energy to other molecules, or these electrons themselves get transferred to other molecules.

Hence, they release the energy they had captured from light. This energy is then used by other molecules to form sugar and other nutrients by using carbon dioxide and water.

In an ideal situation the pigments must be capable of absorbing light energy of the entire wavelength, so that the maximum energy can be absorbed. To do so, they should appear black, but chlorophylls are actually green or brown in color and absorb light wavelengths in the visible spectrum. If the pigment starts absorbing wavelength away from the visible light spectrum, such as ultraviolet or infrared rays, the free electrons may gain so much energy that they will either get knocked off their orbit or may soon dissipate energy in the form of heat, thus damaging the pigment molecules.

So it is the visible wavelength energy absorbing capability of pigment that is important for photosynthesis to take place. However, none of these should be considered a photosynthetic pigment. Photosynthetic pigments are the only pigments that have the ability to absorb energy from sunlight and make it available to the photosynthetic apparatus.

In land plants, there are two classes of these photosynthetic pigments, the chlorophylls and the carotenoids. Among the most important molecules for plant function are the pigments.

Plant pigments include a variety of different kinds of molecules, including porphyrins , carotenoids , and anthocyanins. All biological pigments selectively absorb certain wavelengths of light while reflecting others.

The light that is absorbed may be used by the plant to power chemical reactions , while the reflected wavelengths of light determine the color the pigment will appear to the eye. Pigments also serve to attract pollinators. Chlorophyll is the primary pigment in plants; it is a porphyrin that absorbs red and blue wavelengths of light while reflecting green.

It is the presence and relative abundance of cholophyll that gives plants their green color. All land plants and green algae possess two forms of this pigment: cholorphyll a and cholorphyll b.

Kelps , diatoms , and other photosynthetic heterokonts contain chlorophyll c instead of b , while red algae possess only chlorophyll a. We compared three methods that suppress CLH activity with a conventional acetone-extraction method. In the first method, Arabidopsis leaves were boiled for a short time 5 or 10 sec. This procedure almost completely suppressed chlorophyllide formation with Arabidopsis and G. Bacon and Holden [ 17 ] already reported that a 5 minute period of boiling eliminates chlorophyllide formation.

Their boiling time, however, appears to have been too long since they observed extensive decomposition of the pigments [ 17 ]. In principle, the boiling time used in this procedure should be optimized for each plant species but we do not suggest boiling leaves for more than 10 sec for most plant species see Figure 8. Thicker leaves may necessitate a longer boiling time.

For example, we found that a 30 sec boiling time worked well to eliminate CLH activity in mulberry leaves in our laboratory data not shown. This method appears to have another advantage in increasing the extraction efficiency of pigments from thicker leaves such as pea leaves when pigments are extracted by immersing leaves in organic solvents see Figure 8 C.

Thus, the boiling method combined with the use of DMF as an extractant would be worth testing when pigments are extracted from thicker leaves. A possible drawback of the boiling method is the potential for additional types of modification to chlorophyll molecules. For instance, we observed a slight increase in pheophytin a concentration in our extracts Figure 6 indicating that 0. Thus, the boiling method is recommended in studies where the quantitation of pheophytin a is not being considered.

In the second method, frozen leaves were ground at sub-zero temperatures in a metal box that was cooled with liquid nitrogen.

The use of this shaker facilitates the processing of a relatively large number of samples. It is also possible to use cooled mortar and pestles for grinding leaves at sub-zero temperatures.

However, this approach may be laborious and time-consuming when the analysis of a large number of samples is required. In addition, the recovery of a sufficient amount of solvent from a mortar can be problematic when only a small amount of sample tissue is used or available [ 24 ].

Therefore, the usage of a mortar and pestle with this method is recommended only when a relatively small number of samples need to be analyzed and when a sufficient amount of tissue is available for each sample. Another limitation of this method will be a requirement of liquid nitrogen, which might not be readily available in field research. Regardless of these limitations, this method is superior to other methods in completely suppressing CLH activity in all plant species tested in this study.

This method would be suitable for determining the minimum levels of chlorophyllide formation. In the third method, pigments were extracted with DMF. This solvent has been previously used for pigment extraction [ 24 , 26 ] but, to the best of our knowledge, was not tested for chlorophyllide formation. Therefore, the use of DMF appears to be the best option for extracting photosynthetic pigments from this model organism for downstream analysis using HPLC without introducing artifacts.

However, this solvent is not as effective for G. Moreover, this solvent is a possible liver toxin [ 30 ] and all appropriate safety guidelines should be adhered to in its use. Although the volatility of DMF is low, it should be carefully handled in an exterior venting fume hood.

In conclusion, the use of DMF might be restricted to Arabidopsis or similar plant species under well-ventilated laboratory conditions. We demonstrated that the most-widely used acetone-based procedures for the extraction of photosynthetic pigments from leaf samples potentially results in the rapid, artifactual conversion of chlorophyll to chlorophyllide, especially when pigments are extracted from leaves with high amounts of CLH.

This alteration affects HPLC analysis of photosynthetic pigments by decreasing the apparent content of chlorophyll in extracts. The artifactual conversion can be prevented or reduced by adopting one of three simple methods described in this study, namely, short-time boiling of samples prior to extraction with acetone, extraction at sub-zero temperatures, and the use of DMF as a solvent.

A researcher may consider one of the three extraction methods depending on the plant material, availability of equipment or liquid nitrogen, and the purposes of pigment analysis. Acetone HPLC grade, For pigment extraction, leaves 7th to 9th leaves counting from the bottom of the plant were harvested either after 4 weeks or after a period of 8 weeks to allow natural senescence.

For dark-induced senescence, the 7th-9th leaves of 4-week-old plants were detached and placed on wet filter paper 3 mM MES buffer, pH 5. In addition to Arabidopsis, three other plant species were tested in this study.

Glebionis coronaria garland chrysanthemum adult plants were purchased from a supermarket, and their mature leaves were used for the experiments. Pisum sativum L. Then, young leaves were harvested for pigment extraction. Young leaves of Prunus sargentii Rehd. Leaves were harvested and the fresh weight 18—30 mg of each sample was recorded. In most experiments described in this study, pigments were extracted by immersing leaves in organic solvents for 10 to 48 hours.

Incubation time and the organic solvent were varied from experiment to experiment, which is described in the result section. The procedure described below is common to all extraction methods used in this study unless otherwise noted.

The time length of incubation was determined for each plant species by preliminary experiments. In the boiling method, the leaves were dipped into boiling water for 5 or 10 sec. The leaves were then placed on filter paper to absorb excess water and then homogenized in pure acetone at room temperature. Alternatively, four-degree acetone was added to the boiled samples in a 2-ml microtube.

After incubation, extracts were transferred to a glass vial and analyzed using HPLC as described below. An aluminum metal box BioMedical Science Co. Homogenization of the tissue was performed immediately by shaking the sample tubes containing the homogenization beads and leaf samples in an automatic bead shaker Shake Master, BioMedical Science Co.

Ltd, Tokyo, Japan. Subsequently, the organic solvent was recovered by centrifugation and its pigment composition was determined by HPLC as described below. Elution profiles were monitored by measuring absorbance at nm.

Pigments used as standards were purchased from Juntec Co. Odawara, Japan. Leaf samples from 4-week-old Arabidopsis plants were immersed in pure acetone in 2. The sample tubes were then transferred to a tube rack and incubated at ambient temperature for the times indicated in Figure 4. After a prescribed time, the tubes were returned to the nitrogen-cooled metal box to terminate the incubation.

Pigments were extracted from samples at a sub-zero temperature while tubes were in the cooled metal box by adding stainless beads and shaking the box in a bead shaker Shake Master. New Phytol. Plant Cell Environ. Article PubMed Google Scholar. Can J Fish Aquat Sci. Funct Ecol. Article Google Scholar. Oserkowsky J: Quantitative relation between chlorophyll and iron in green and chlorotic pear leaves.

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