Some Like It Hot

摘要

Photosynthesis—the process through which green plants harvest light energy to make organic compounds from water and carbon dioxide (CO_2)—is inhibited by moderate to high temperatures, but the causes of this inhibition are not clear. An increase in temperature is thought to be detrimental to the membranes of chloroplasts—the organelles, akin to mitochondria, where photosynthesis takes place—but this has been difficult to prove at moderate temperatures (about 35℃) known to inhibit photosynthesis in many plants. The decreased photosynthesis at moderate temperatures could also be due to a corresponding increase in respiration or photorespiration, or a decline in the activation state of the CO_2-fixing enzyme rubisco. On page 476 of this issue, Murakami et al. now provide the best evidence yet that the number of unsatu-rated lipids (that is, fatty acids with double bonds) in the thylakoid membrane of chloroplasts—which contain the light-absorbing system, electron transport chain, and ATP synthase—is important in determining a plant's ability for growth and photosynthesis at temperatures of 35℃ or more.