Programmed cell death begins earlier in the mesophyll cells of tulip petals than in the epidermal cells

► Programmed cell death (PCD) was examined in epidermal and mesophyll cells of tulip petals. ► Before any wilting was visible, DNA fragmentation was evident only in mesophyll cells. ► Protein content decreased and proteinase was activated early in mesophyll cells. ► The onset of PCD occurred earlier in mesophyll cells than in epidermal cells.