Light- and CO2-Dependent Systemic Regulation of Photosynthesis

Plant leaves do not only sense and respond to their local environment but also the environment experienced by the other leaves within the same plant. This long-distance signaling is involved in the systemic regulation of various photosynthesis-related phenotypic features of leaves. Here, we summarize the recent research on light- and CO2-dependent, leaf-to-leaf systemic regulation. In the short term, leaves can pre-acclimate to excess light at the transcriptional level, in response to systemic signals from other leaves. Several substances, including reactive oxygen species and phytohormones, have been suggested to play key roles in the signaling pathway. In the long term, the light and CO2 environment around mature leaves systemically regulates stomatal development, anatomical structure, and photosynthetic characteristics of young leaves. Possible mechanisms underlying the systemic regulation and the potential importance of systemic regulation in horticultural crop production are discussed.