Photosynthesis in Carnivorous Plants: From Genes to Gas Exchange of Green Hunters

Abstract

Although carnivorous plants can obtain organic carbon from their animal prey, they rely on photosynthetic assimilation of carbon dioxide. All investigated carnivorous plant species assimilate carbon dioxide using the C3 pathway, with the rate of photosynthesis (AN) being lower in comparison to noncarnivorous species. The reasons for low AN in carnivorous plants are (i) low nitrogen and phosphorus content in the soil and leaves and (ii) the cost of carnivory in their modified leaves (called traps). The cost of carnivory includes several anatomical, ultrastructural, and biochemical adaptations of traps, which favor nutrient uptake from prey over photosynthetic assimilation. However, after digestion, nutrient uptake from the prey can increase AN, growth, and reproduction. In carnivorous plants with active trapping mechanisms, spatiotemporal changes in AN and respiration rate (RD) occur during prey capture and digestion, owing to the interplay of electrical and hormonal signaling. Approximately 7.5% of carnivorous plants are aquatic plants, with demands for survival being different from those of terrestrial plants. The alternative mode of nutrition in carnivorous plants is reflected in their plastid genomes, which resemble the reduced plastomes of parasitic and mycoheterotrophic plants.