Antagonistic kinesin-14s within a single chromosomal drive haplotype

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• Maize meiotic drive systems, Abnormal chromosome 10 (Ab10) and K10L2, operate on tandem repeat arrays (knobs).
• Ab10 encodes KINDR/knob180 and TRKIN/TR-1 kinesins; K10L2 encodes only TRKIN/TR-1.
• Previous research indicated KINDR/knob180 is the primary driver, with TRKIN/TR-1 playing a minor role.

Purpose of the Study:

• To investigate the role of the TRKIN/TR-1 system in maize meiotic drive.
• To characterize the K10L2 haplotype using long-read sequencing.
• To assess the impact of TRKIN gene function on Ab10 and K10L2 meiotic drive and fitness.

Main Methods:

• Long-read sequencing to assemble the K10L2 haplotype.
• CRISPR mutagenesis to inactivate the Trkin gene.
• Modeling to predict the population dynamics of Trkin.

Main Results:

• K10L2 shares homology with an internal region of Ab10.
• Trkin on Ab10 has a slightly deleterious effect on drive and fitness when paired with a normal chromosome 10.
• Functional Trkin on either Ab10 or K10L2 severely reduces Ab10 drive when paired with K10L2.

Conclusions:

• The Trkin gene does not enhance Ab10 drive or fitness and may be deleterious.
• The persistence of Trkin in Ab10 populations is questionable.
• Trkin might confer an unobserved advantage or is undergoing purging from the Ab10 population.