Be the first to like this
Genome size in plants can vary by orders of magnitude, but this variation has long been considered to be of little to no functional consequence.
Studying three independent adaptations to high elevation in Zea mays, we find that genome size experiences parallel pressure from natural selection, causing a linear reduction in genome size with increasing altitude.
Though reductions in repetitive content are responsible for the genome size change, we find that repeats are not targeted uniformly, but that the same repetitive sequences are removed as Z. mays taxa move to higher altitude.
To identify the phenotype influenced by genome size, we study how 20% variation in genome size in a single teosinte population impacts leaf growth.
We find that genome size variation correlates negatively with cell production rate but not cell size, suggesting that individuals with larger genomes require longer to complete a mitotic cycle.
We reanalyze data from maize inbreds to show that slower cell production can lead to a delay in flowering time, suggesting that genome size can be used as a developmental clock to help adapt maize to different altitudes.