genotypebyenvironment

Genotype by environment interaction, often abbreviated as GxE, refers to the phenomenon in which the effect of a genotype on a phenotype varies across different environmental conditions. In other words, the relative performance of genotypes changes depending on the environment, making genetic effects non-additive with respect to environmental context.

GxE is central in genetics, plant and animal breeding, forestry, and ecology. In plant breeding, recognizing GxE leads to strategies for broad adaptation—genotypes that perform well across many environments—and specific adaptation—genotypes optimized for particular environments. This concept also helps explain why a superior genotype in one setting may underperform in another.

Measurement and analysis typically rely on multi-environment trials that span different locations and years. Statistical approaches include analysis of variance with interaction terms, linear mixed models, and dimension-reduction methods such as the additive main effects and multiplicative interaction (AMMI) model and GGE biplots. The idea of a reaction norm, which describes how a genotype’s phenotype changes along an environmental gradient, is another commonly used framework.

Implications of GxE include effects on the estimation of genetic merit and on breeding decisions. Breeders may select for stability and broad adaptation or exploit specific adaptation to target environments. In ecological genetics, GxE relates to phenotypic plasticity and local adaptation, illustrating how organisms optimize performance across diverse habitats.