The syncytium-specific expression of the Orysa;KRP3 CDK inhibitor: implication of its involvement in the cell cycle control in the rice (Oryza sativa L.) syncytial endosperm

摘要: During rice (Oryza sativa L.) seed development, the primary endosperm nucleus undergoes a series of divisions without cytokinesis, producing multinucleate cell, known as syncytium. After several rounds rapid nuclear proliferation, syncytium ceases to undergo mitosis; thereafter, is partitioned into individual cells by specific type cytokinesis called cellularization. The transition between and cellularization important in determining final size model for studying cell cycle cytokinesis. involvement cyclin-dependent kinase (CDK) inhibitors (CKIs) control was investigated here during It found that one CKIs, Orysa;KRP3, strongly expressed caryopsis at 2 d after flowering (DAF), its expression significantly reduced 3 DAF. other CKI transcripts did not show such shift In situ hybridization analysis revealed Orysa;KRP3 syncytial DAF, but cellularized Two-hybrid assays showed binds Orysa;CDKA;1, Orysa;CDKA;2, Orysa;CycA1;1, Orysa;CycD2;2. By contrast, Orysa;CDKB2;1 Orysa;CycB2;2 do binding Orysa;KRP3. able rescue yeast premature division due dominant positive mutant CDKA;1 indicating inhibited CDK. These data suggest involved endosperm.