Abnormal endosperm development causes female sterility in rice insertional mutant OsAPC6

Area of Science:

• Plant genetics
• Molecular biology
• Reproductive biology

Background:

• The anaphase promoting complex/cyclosome (APC/C) is crucial for cell cycle regulation.
• APC6 is a key subunit of the APC/C complex, essential for proper cell division.
• Understanding APC/C function in plants is vital for crop development and yield.

Purpose of the Study:

• To investigate the function of the rice APC6 gene in plant development and reproduction.
• To characterize the phenotype of a T-DNA insertional mutant of OsAPC6.
• To elucidate the role of APC6 in female gametogenesis and seed development.

Main Methods:

• T-DNA insertional mutagenesis in rice (Oryza sativa).
• Phenotypic analysis of the OsAPC6 mutant, including plant height and seed set.
• Confocal laser scanning microscopy (CLSM) to study megagametophyte development.
• Meiosis and pollen viability assessments.

Main Results:

• The OsAPC6 mutant exhibited gibberellic acid insensitivity, reduced height, and up to 45% reduced seed set.
• Meiosis and pollen viability were normal, but megagametophyte development showed abnormal mitotic divisions.
• Approximately 30-35% of mutant megagametophytes lacked sufficient polar nuclei, leading to failed endosperm and seed development.
• The mutant demonstrated high sterility and segregated tall, gibberellic acid-sensitive plants, suggesting maintenance in a heterozygous state.

Conclusions:

• OsAPC6 is essential for normal female gametogenesis and seed development in rice.
• Inactivation of APC6 disrupts cell cycle progression during megagametogenesis, causing sterility.
• The OsAPC6 mutant can be maintained as a heterozygote due to segregation patterns in selfed progeny.