Plant Pigments

...

Original Color

Change

T0- Distilled Water

Black

Black

T1- 0.1 M HCL

Black

Red

T2- 0.01 M KOH

Black

Violet

T3- 0.1 M KOH

Black

Dark green

T4- 1 M KOH

Black

Top: Green Bottom: Yellow

Part 3. Determination of Pigment location of the Cell

[pic 6][pic 7]

Fig. 6) Tomato fruit’s epidermal cells Fig. 7) Pigweed stem’s epidermal cells

Total Magnification: 400x Total Magnification: 400x

[pic 8]

Fig. 8) Purple heart leaves’s epidermal cells

Total Magnification: 400x

V. Discussion

During part 1 of the experiment, two phases was formed, the hydrophobic phase (petroleum ether) and hydrophilic phase (acetone and ether). In figure 1, the pigments moved toward the hydrophobic phase therefore tomato pigments are hydrophobic. Among the non-photosynthetic pigments, carotenoids have the same characteristic with the tomato pigments; they are not soluble in water (hydrophobic) so carotenoids are present in tomato fruit. It is also evident in the microscopic view of the epidermal cell of the tomato fruit that the carotenoids are located in the cell wall, usually in the cell membrane and not in the central vacuole because it is hydrophobic. In figures 2 and 3 the pigments stayed in the hydrophilic phase and, thus, they are hydrophilic pigments. Figures 7 and 8 also proved that pigweed and purple heart pigments are hydrophilic because they are found in the central vacuole of the plant cell that is occupied with water. These pigments can either be anthocyanins or betalains because both are soluble in water. In the second part of the experiment, there are visible changes in color observed in the 3 subjects (tomato fruit, pigweed stem and purple heart leaves extracts) after various treatment solutions were added. The addition of increasing concentrations of KOH (potassium hydroxide) will make the pH of the extracts more basic and will certainly make changes in the color of the extracts. The tomato fruit extract did not actively react with the treatment solutions and only slight changes in color are seen. In the pigweed stem extract there was only one test tube which reacted with the treatment solution and has a different color (yellow green) from the rest of the test tubes. The purple heart leaves extract, however, reacted sensitively with the treatment solutions and its color varied upon the concentration of the treatment solutions. Considering that anthocyanins and betalains are soluble in water, it is now clear that they can be distinguished because anthocyanins react sensitively with pH but betalains do not.

VI. Conclusion

Anthocyanins and betalains are hydrophilic pigment because they are soluble in water and it is located in the central vacuole of a plant’s cell. Carotenoids on the other hand are hydrophobic pigments and lipid soluble and are found in the cell membrane of a plant’s cell which consists of phospholipid bilayer. Anthocyanins react sensitively with pH changes while betalains do not. Because of the different effects on pH of the anthocyanins, the two water soluble pigments (anthocyanins and betalains) are distinguished.

VII. Reference

1.) Darrell S. Vodopich, 1998, Botany 2nd Edition, 2021 Avenue of the Americas NY, Macgrow-Hill

Companies Inc.

2.) http://science.jrank.org/pages/5307/Plant pigment. Htm/