|Budget Amount *help
¥2,700,000 (Direct Cost : ¥2,700,000)
Fiscal Year 1998 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1997 : ¥2,100,000 (Direct Cost : ¥2,100,000)
Arabidopsis has three types of vacuolar processing enzyme homologues ; αVPE, βVPE, and γVPE. The temporal and spatial expression of these VPE genes were detected with GUS histochemical staining of pVPE::gus transformed Arabidopsis plants. The αVPE and γVPE promoters directed the expression in root and leaves. On the contrary, pβVPE::gus gene was strongly expressed in pollen grains. In this investigation, we have clarified the ultrastructural changes of the vacuolar organelle with the pVPE-gus gene-expression. The ultrastructure was examined with cryo-freezing/freezesubstitution electron microscopy. In immature pollen grain, in which pβVPE::gus gene had not been expressed, vacuoles kept similar appearance as those in vegetative cells. A large vacuole was occurred in the cytoplasm just before generative cell formation. Golgi bodies did not actively produce secretory vesicles, even during cell wall formation. In mature pollen grains of the flowers just before bloom, in which pβVPE::gus gene was expressed, the vegetative vacuoles had disappeared and storage vacuoles, many vesicles, and lipid droplets surrounded by rER appeared. The materials in the storage vacuoles with βVPE would be used for pollen germination and early pollen tube elongation. In the pollen of blooming flowers, lytic vacuoles appeared. This vacuole-transformation was discussed in relation to the vacuole functions.