Single gametophyte sequencing reveals that crossover events differ between sexes in maize

Area of Science:

• Genetics
• Plant Biology
• Molecular Biology

Background:

• Meiotic crossover (CO) is crucial for gametophyte production and genetic variation.
• CO patterns vary between species and sexes, but sex-specific maize COs lack detailed profiling.
• Understanding these differences is key for crop improvement.

Purpose of the Study:

• To profile sex-specific meiotic crossover patterns in maize independently of genetic background.
• To investigate the molecular mechanisms underlying CO production differences between male and female gametes.
• To explore the potential of maize as a model for studying CO maturation inefficiency (CMI).

Main Methods:

• Development of a novel method for isolating single female gametophytes for genome sequencing.
• Comparative analysis of CO frequencies and types (Class I and II) in male and female gametes.
• Application of the Beam-Film model for CO classification.

Main Results:

• Significantly higher COs in male (19.3/microspore) compared to female (12.4/embryo sac) maize gametes.
• Differential distribution of Class I and Class II COs between sexes, as predicted by the Beam-Film model.
• Identification of CO maturation inefficiency (CMI) in specific genetic backgrounds.

Conclusions:

• Maize exhibits distinct sex-specific meiotic crossover patterns.
• The findings provide insights into the molecular mechanisms of sexual dimorphism in COs.
• Maize serves as a valuable model for dissecting CMI and can aid in improving breeding efficiency via paternal selection.