Domain-Specific Variants Result in Positive Epistasis Stabilizing Terpene Synthase Structure and Ligand Binding in Coffea arabica Populations from Saudi Arabia

Coffea arabica is an allotetraploid crop species with limited genetic diversity. Its terpenesynthase (TPS) gene family plays a central role in flavor chemistry and ecological adaptation.Whole-genome sequencing followed by TPS gene family identification and variant analysis in C.arabica populations from Saudi Arabia revealed 69 TPS genes, of which only five carriedvariants, consistent with strong purifying selection acting on this family.