XVI International Botanical Congess

With the aim to understand the whole mechanism of senescence program in higher plants, we studied the sequence of senescence-related events in rice leaves using fluorescence and electron microscopy. Although the timing of each step was differed among cells of different locations, all greening cells both in the coleoptile and the second leaf blade senesced in the same order, (i) degradation of the chloroplast DNA, (ii) degradation of the thylakoid membranes, condensation of the nucleus, (iii) disorganization of the nucleus, (iv) distortion of the cell wall and complete loss of cellular components (Inada et al. 1998, 1999). These facts indicate directly that the identical program of senescence exsists in the rice leaves.