A Pan-Genomic Perspective: Comprehensive Dissection of the FIG Superfamily Unravels Its Evolution, Expansion, and Environmental Adaptation in Wheat

Background As a major global food crop, wheat faces dual pressures from population growth and deteriorating agricultural environments in efforts to increase its yield. The FIG superfamily, which plays a central role in photosynthetic carbon fixation and stress adaptation, represents a potential target for wheat genetic improvement. Results In this study, we conducted the first systematic pan-genomic analysis to investigate the evolution and function of the FIG superfamily in wheat. The results revealed that this family underwent significant expansion during plant evolution from aquatic to terrestrial habitats and from lower to higher forms, with functional divergence predating the green algal evolutionary stage. The members of this family were primarily derived from three ancestral species, and their expansion was largely driven by whole-genome duplication. Most members were found to be under purifying selection, whereas the TaVTC4-4B was subjected to positive selection. This gene is constitutively highly expressed in green tissues, and its promoter is enriched with cis-regulatory elements associated with light responsiveness, JA/ABA signaling, and stress responses. Expression analysis confirmed its strong responsiveness to salt stresses. Conclusions This study elucidates the evolutionary trajectory and functional landscape of the wheat FIG superfamily, providing a new foundation for precision breeding aimed at improving photosynthetic efficiency and stress resilience in wheat.