Abstract
Plants develop sun and shade leaves depending on light environment. Although information of differences in physiological traits and leaf anatomies between sun and shade leaves has been accumulated, analyses of their developmental processes were rarely carried out. Recently, it was reported in several plants that development of new leaf is affected by light environment of mature leaves but not their own one. These facts indicate long-distance signaling from mature leaves to leaf primordia. We hypothesized that photosynthates might be the signal. To test this hypothesis, we anatomically analyzed Arabidopsis thaliana grown on various sucrose-concentration medium under 60 μmol m-2 s-1, under which plants grown on soil develop thin leaves with one-cell layered palisade tissue. With the increase of sucrose concentration, the leaves developed thick lamina and two-cell-layered palisade tissue. These results support our hypothesis. Analyses of some mutants with defects in photo- or sugar- sensing will also be introduced.
