How do CAM plants utilize malate during the day?

CAM plants, or Crassulacean Acid Metabolism plants, have a unique adaptation that allows them to minimize water loss in arid conditions by limiting gas exchange to the nighttime. During the night, these plants fix carbon dioxide into malate, which is then stored in vacuoles. When daytime arrives, the stomata close to conserve water, and the stored malate is transported to the sites where RuBisCO, the enzyme responsible for carbon fixation, is located.

At this point, the malate is decarboxylated, releasing carbon dioxide for use in the Calvin cycle, where photosynthesis occurs. By regulating the release of malate near RuBisCO, CAM plants efficiently make use of carbon dioxide while keeping the stomata closed during the day, preventing excessive water loss. This process distinguishes CAM plants and enables them to thrive in environments where other plants may struggle due to water scarcity.