Teosinte introgression modulates phosphatidylcholine levels and induces early maize flowering time

Abstract

AbstractAfter domestication from lowland teosinte parviglumis (Zea mays ssp.parviglumis) in the warm Mexican southwest, maize (Zea mays ssp. mays) colonized the highlands of México and South America. In the highlands, maize was exposed to lower temperatures that imposed strong selection on flowering time. Phospholipids are important metabolites in plant responses to low-temperature, low phosphorus availability and have also been suggested to influence flowering time.Here, we combined linkage mapping analysis with genome scans to identify High PhosphatidylCholine 1 (HPC1), a gene which encodes a phospholipase A1 enzyme, as a major driver of phospholipid variation in highland maize. Common garden experiments demonstrated strong genotype-by-environment interactions associated with variation at HPC1, with the highland HPC1 allele leading to higher fitness in highlands, possibly by hastening flowering.The highland maize HPC1 variant results in impaired function of the encoded protein due to a polymorphism in a highly conserved sequence. A meta-analysis indicated a strong association between the identity of the amino acid at this position and optimal growth in prokaryotes. Mutagenesis of HPC1 via genome editing validated its role in regulating phospholipid metabolism.Finally, we showed that the highland HPC1 allele entered cultivated maize by introgression from the wild highland teosinte Zea mays ssp. mexicana and has been maintained in maize breeding lines from Northern US, Canada and Europe.Thus, HPC1 introgressed from teosinte mexicana underlies a large metabolic QTL that modulates phosphatidylcholine levels and has an adaptive effect at least in part via induction of early flowering time..