Sperm Identification in Maize by Fluorescence in Situ Hybridization

Area of Science:

• Plant genetics
• Reproductive biology
• Cytogenetics

Background:

• Flowering plants have two sperm cells per pollen grain, each participating in fertilization.
• Maize lines with B chromosomes exhibit preferential fertilization by one sperm type.
• Distinguishing between sperm cells has been challenging due to a lack of detectable differences.

Purpose of the Study:

• To develop a method for identifying and tracking B chromosome-containing sperm cells in maize.
• To investigate the behavior and fate of B chromosome-carrying sperm during fertilization.

Main Methods:

• Utilized a B chromosome-specific DNA sequence (pZmBs) for identification.
• Employed in situ hybridization to visualize and track sperm cells within pollen and pollen tubes.
• Correlated findings with existing genetic studies on B chromosome behavior.

Main Results:

• Successfully identified and tracked B chromosome-containing sperm using the pZmBs DNA sequence and in situ hybridization.
• Results align with previous genetic studies on B chromosome segregation during pollen development.
• Observed that the B chromosome-containing sperm's position (leading or trailing) in pollen tubes is random relative to the other sperm cell.

Conclusions:

• The study provides a reliable method to distinguish and track B chromosome-containing sperm cells.
• Confirms the preferential fertilization of the egg by B chromosome-carrying sperm in maize.
• Demonstrates the random spatial arrangement of sperm cells within the pollen tube, irrespective of B chromosome content.