Physiological adaptive traits are a potential allele reservoir for maize genetic progress under challenging conditions
Claude Welcker, Nadir Abu-Samra Spencer, Olivier Turc, Ítalo Stefanine Correia Granato, Romain Chapuis, Delphine Madur, Katia Beauchêne, Brigitte Gouesnard, Xavier Draye, Carine Palaffre, Josiane Lorgeou, Stéphane Melkior, Guillaume Colin, Thomas Presterl, Alain Murigneux, Randall J. Wisser, Émilie Millet, Fred A. van Eeuwijk, Alain Charcosset, François Tardieu
Abstract
Abstract Combined phenomic and genomic approaches are required to evaluate the margin of progress of breeding strategies. Here, we analyze 65 years of genetic progress in maize yield, which was similar (101 kg ha −1 year −1 ) across most frequent environmental scenarios in the European growing area. Yield gains were linked to physiologically simple traits (plant phenology and architecture) which indirectly affected reproductive development and light interception in all studied environments, marked by significant genomic signatures of selection. Conversely, studied physiological processes involved in stress adaptation remained phenotypically unchanged (e.g. stomatal conductance and growth sensitivity to drought) and showed no signatures of selection. By selecting for yield, breeders indirectly selected traits with stable effects on yield, but not physiological traits whose effects on yield can be positive or negative depending on environmental conditions. Because yield stability under climate change is desirable, novel breeding strategies may be needed for exploiting alleles governing physiological adaptive traits.