What Is Red Chlorophyll?

Red chlorophyll is a rare red pigment found in a very small percentage of marine plants. Like green chlorophyll, it allows the plants to absorb light to begin photosynthesis, the process by which plants convert energy into food. Plants containing red chlorophyll typically fall into the category of cyanobacteria, or microscopic plants that grow in small colonies on coral reefs and stationary marine animals, like sea squirts.

One particular species of cyanobacterium contains red chlorophyll, also classified as chlorophyll d or chlorophyll f. Called Acaryochloris marina, these cyanobacteria appear red in color, making them unlike the rest of their species. The ancient Greeks gave cyanobacteria their name because cyano means 'blue-green.' Acaryochloris marina does not share this color trait, but shares the same cellular structure, growth patterns, and environmental needs as the rest of its species. Cyanobacteria filled with this chlorophyll can also grow at lower depths than its blue-green cousins.

This variety of marine flora shows up red on the light spectrum because it absorbs infrared light on the extreme end of the light spectrum and reflects visible red light. Infrared light wavelengths are much longer than those in the visible spectrum, allowing them to penetrate deep into the ocean. Most other lights, especially the blues and purples on the short end of the spectrum, are filtered out of the light that travels into the water. If Acaryochloris marina could not absorb infrared light, it could not survive.

There are two kinds of red chlorophyll: chlorophyll d and chlorophyll f. The first kind absorbs infrared light just outside of the visible spectrum, generally measuring 700 wavelengths or more. The second variety absorbs infrared light in the 800 wavelength range and higher. Plants containing chlorophyll f can survive deeper in the ocean than those containing chlorophyll d, though both kinds of chlorophyll require sunlight.

Scientists interested in genetically engineering plants are trying to find a way to make ordinary farmers’ crops produce red chlorophyll. Above the water, red chlorophyll would, theoretically, absorb much more sunlight than green chlorophyll. Green chlorophyll absorbs blue and purple rays of light on the short side of the visible light spectrum, meaning that the rays it absorbs aren’t as strong as red and infrared light. Terrestrial plants able to absorb long, strong infrared rays of light might be able to photosynthesize at a very high rate, meaning they would mature and produce crops very quickly.

Red chlorophyll, also known as chlorophyll f, is a type of chlorophyll that absorbs light in the far-red spectrum, beyond the range of traditional green chlorophyll a and b. It allows photosynthetic organisms to utilize light that is less accessible to most plants, expanding their ability to perform photosynthesis in low-light environments, such as at greater depths in water.

Red chlorophyll is primarily found in certain species of cyanobacteria and some red algae. These organisms often inhabit environments where light is limited or filtered, such as in deep water or shaded areas, where longer-wavelength far-red light penetrates more effectively than the shorter wavelengths absorbed by green chlorophyll.

Red chlorophyll plays a crucial role in photosynthesis by capturing far-red light that green chlorophyll cannot absorb. This adaptation is particularly important in shaded or deep-water ecosystems, where it allows photosynthetic organisms to thrive and produce oxygen, even with limited sunlight, thus supporting diverse biological communities.

Red chlorophyll was discovered through scientific research on photosynthetic organisms that thrive in low-light conditions. Advanced spectroscopy techniques revealed the presence of a pigment capable of absorbing far-red light, leading to the identification of chlorophyll f as a distinct type of chlorophyll, expanding our understanding of photosynthesis.

While red chlorophyll itself absorbs far-red light, it does not necessarily change the overall color of the plants that contain it. The visible color of these organisms is often a combination of various pigments, including green chlorophylls, carotenoids, and phycobiliproteins, which can mask the presence of red chlorophyll.

Red chlorophyll has potential biotechnological applications, such as in the development of more efficient solar cells that mimic photosynthesis. By harnessing the ability of red chlorophyll to absorb a broader spectrum of light, researchers aim to create bio-inspired solar energy systems with improved light capture, especially in low-light conditions.