The Leafless Orchid <i>Cymbidium macrorhizon</i> Performs Photosynthesis in the Pericarp during the Fruiting Season

Abstract Photosynthesis with highly photoreactive chlorophyll (Chl) provides energy for plant growth but simultaneous risk of photooxidative damage and photoprotection costs. Although the leafless orchid Cymbidium macrorhizon mostly depends on mycorrhizal fungi carbon, it accumulates Chl particularly during fruiting may not be fully mycoheterotrophic. In fact, stable isotopic analysis suggested that C. specimens obtain a significant proportion its carbon demands through photosynthesis. However, actual photosynthetic characteristics this are unknown. To reveal functionality electron transport in macrorhizon, we compared properties those relative mixotrophic goeringii model Arabidopsis thaliana. Compared A. thaliana, maximum photochemical efficiency PSII was substantially low macrorhizon. fluorescence induction kinetics revealed capacity limited at 77 K partial energetic disconnection light-harvesting antenna from reaction center Despite efficiency, showed activity both field under laboratory conditions. developed strong nonphotochemical quenching response to increased light intensity as did goeringii, suggesting photoprotective systems orchid. Moreover, fruit stomata pericarp net O2-evolving activity. Our data demonstrate can perform pericarp, although contribution acquisition limited.