Non-foliar photosynthesis – a strategy of additional carbon acquisition

In addition to the green leaves, commonly considered as the primary sources of photosynthate production, higher plants can potentially use almost all vegetative and reproductive structures to perform photosynthetic CO2 assimilation. Green leaves, stems and green sterile flower organs, optimized for light harvesting and photosynthetic performance, are characterized by net photosynthetic assimilation utilizing mainly the atmospheric carbon dioxide. In contrast, chlorophyll-containing bark and wood tissue, most fruit, root and fertile flower organs are principally sub-ordinated to non-photosynthetic functions, but typically perform an effective internal CO2 recycling using the respiratory released CO2. Non-foliar photosynthesis, either manifested as net photosynthesis or internal CO2 refixation is regarded as an important strategy of additional carbon-acquisition. While chlorophyllous stems or aerial roots even can serve as primary photosynthetic organs, reproductive structures could derive up to 60%; of their total carbon requirement from own CO2 fixation. In the review, the main strategies of additional carbon acquisition by non-foliar photosynthetic organs are illustrated, presenting an extensive compilation of published data completed with relevant own studies.