Green & Fat
Many fruit-bearing plants rely on mobile animals to disperse their seeds. Brightly pigmented fruits are viewed as an adaptation that makes them more visible to animals and more marketable in grocery stores. Leaves on the other hand, and please excuse the gross over-generalization, tend to be green.
Leaves possess organelles called chloroplasts that help generate energy from sunlight through a process called photosynthesis. This energy conversion is made possible by chlorophyll, a pigment that captures red and blue light and reflect green light.
Avocados are fruit . . . but avocados are green. Does that mean that avocados contain chloroplasts just like leaves? Well . . . yes.
The outer layers of flesh in an avocado fruit contain chloroplasts. Light penetrating past the bumpy rind of the fruit allows these chloroplasts to mature and produce chlorophyll. The inner layers of the fruit, where light cannot reach, contains chloroplasts that remain in an immature state called “etioplasts.” That is why the flesh of the avocado fruit has a gradient of green close to the rind transitioning to light green and yellow towards the pit.
Unlike in leaves, the chloroplasts in avocado fruit are not major contributors to photosynthesis. Instead, they function in the production of fatty acids. The activity of these tiny organelles is the reason why avocados are packed full of energy-rich, heart healthy fats and why, ultimately, I smashed one all over my morning toast.
And there you go. Now you know what plant biologists think about in the morning during breakfast but before coffee.
Brian Rutter, PhD, is the cofounder of Hundredfold Video and plant biologist working for 2Blades at the University of Minnesota. Subscribe to our newsletter to receive our “Sower Stories – Odd Facts About Plants” and video production tips in your inbox every month!
Works Cited:
Cran, D. G., and J. V. Possingham. "The fine structure of avocado plastids." Annals of Botany 37, no. 5 (1973): 993-997.
Opiyo, Sylvia A., Beatrice J. Mugendi, Peter W. Njoroge, and Samuel N. Wanjiru. "A review of fatty acid components in avocado." (2023).
Weaire, P. JOHN, and R. G. Kekwick. "The synthesis of fatty acids in avocado mesocarp and cauliflower bud tissue." Biochemical Journal 146, no. 2 (1975): 425-437.
