The pattern of cuticular blue-fluorescing phenolics deposition during the development of Prunus persica leaves

Although stomatal ontogeny is closely related to the development and maturation of the epidermal tissue, stomatal patterns in relation to cuticle construction and cuticular material deposition during leaf development have not received adequate attention. We observed the deposition of blue-fluorescing cuticular phenolics over guard and epidermal cells, as well as stomatal formation and patterning using the alkali-induced blue fluorescence of the cuticle of Prunus persica leaves. Stomata of different stages of maturity occurred together during leaf development, mainly at the tip of the lamina. The deposition of fluorescing compounds initially appeared over the guard cells of the developing stomata complexes and gradually extended to the neighbouring epidermal cells. Based on the blue fluorescence emitted by the cuticular layers, we constructed digital maps of leaves of different developmental stages, showing the pattern of stomatal formation and deposition of fluorescing compounds. A longitudinal tip-to-base gradient in the formation of stomata, as well as in the deposition of fluorescing compounds was observed in young developing leaves. The deposition of blue-fluorescing phenolic compounds seems to be coordinated with stomatal development.