What Is the Most Abundant Pigment in Green Plants?

Plants store most of their chlorophyll in their leaves.

Plant leaves contain a range of pigments, which give them their colors. These pigments include carotenoids, which produce red, orange and yellow colors in autumn leaves, as well as chlorophyll, which produces the green color of summer leaves. Chlorophyll is also responsible for photosynthesis, the process by which plants convert sunlight into usable energy.

History

Chlorophyll was first discovered at the beginning of the 19th century by scientists Joseph Bienaime Caventou and Pierre Joseph Pelletier. Decades before, Joseph Priestly, Antoine Lavoisier and Jan Ingenhousz all separately discovered plants' ability to oxygenate air by exposure to the sun, but did not actually isolate the compound.

Types

Plant chlorophyll comes in two main types: chlorophyll a and chlorophyll b. These differ by only one small molecular side chain, which enables them to absorb different light wavelengths. Using two different types of chlorophyll allows plants to take in energy from more of the light spectrum than would be possible with just one. Both types cannot absorb much light in the green part of the spectrum, which causes them to look green to the human eye. According to the University of California Museum of Paleontology, plants, algae and cyanobacteria all contain chlorophyll a, while only plants and green algae contain chlorophyll b. A third type, chlorophyll c, occurs only in Chromista algae.

Function

Plants store large concentrations of chlorophyll in organelles called chloroplasts. These organelles capture light energy and use the chlorophyll to convert it to a chemical called adenosine triphosphate (ATP), which the plant uses for storage. According to the University of Cincinnati, this molecule is similar to those that make up the building blocks of DNA. Chloroplasts also convert carbon dioxide into sugar, but don't use light for this process.

Content

Green plants vary significantly in their chlorophyll content, with most of the pigment being stored in the leaves. Thus, foods like spinach and parsley contain significantly higher concentrations of chlorophyll than celery, which comes from the stem of the plant. However, even leafy greens can vary significantly in chlorophyll content. The Linus Pauling Institute at Oregon State University reports that 1 cup of spinach contains close to 24 mg of chlorophyll, while the same amount of Chinese cabbage contains only a little more than 4 mg.

References

• University of California Museum of Paleontology: Photosynthetic Pigments
• Linus Pauling Institute at Oregon State University: Chlorophyl and Chlorophyllin
• Bristol University; Chlorophyll; Paul May
• University of Cincinnati Biology; Photosynthesis; J. Stein Carter