The maize mutant polymitotic affects cell cycle events during microspore development

Area of Science:

• Plant genetics
• Cell biology
• Molecular biology

Background:

• The polymitotic (po) mutant in maize (Zea mays L.) displays male sterility.
• Understanding the cellular basis of this sterility is crucial for plant reproductive biology.

Purpose of the Study:

• To investigate the relationship between the polymitotic mutant phenotype and cell cycle events during microspore development.
• To elucidate the molecular mechanisms underlying abnormal cell divisions in the po mutant.

Main Methods:

• In-vitro cell culture of maize meiocytes.
• Live imaging using a CCD camera and computer image analysis.
• Immunocytochemistry to detect protein localization.

Main Results:

• Abnormal post-meiotic cell cycles were observed in the po mutant following meiosis II.
• Premature chromosomal condensation preceded abnormal cell cycle progression.
• Unsynchronized post-meiotic divisions occurred in vitro without somatic tissue interaction.
• The p34(cdc2) protein kinase shifted from a nuclear to a cytoplasmic location in po mutant tetrads.

Conclusions:

• The polymitotic mutation disrupts normal cell cycle progression after meiosis II in maize.
• Altered p34(cdc2) localization is associated with the unsynchronized post-meiotic divisions in the po mutant.
• These cell cycle defects are intrinsic to the microspore and do not require somatic tissue signaling.