Abstract
The palisade tissue consists of adaxial-side mesophyll cells which elongate under high light conditions. Development of the palisade tissue was reported to be regulated by long-distance signaling from mature leaves in Chenopodium album, but details of this signaling is not clarified. Here, we investigated palisade development induced by long-distance signaling using Arabidopsis thaliana. Elongation of the palisade cells was not observed in low-light grown plants. However, elongated cells were observed in newly formed leaves placed in low light when mature leaves were illuminated with high light. Blue light induces elongation of the palisade cells in Arabidopsis. To investigate if blue light induces long-distance signaling, mature leaves were illuminated with blue light under red-light background. However, elongation of the palisade cells was not observed in newly formed leaves. These results indicate that blue-light signal is not transduced to the meristem as a high-light signal to induce elongation of the palisade cells. We discuss the role of blue light in palisade development and possible factor involved in long-distance signaling in palisade development.
