Dynamic metabolic-QTL analyses provide novel biochemical insights into the kernel development and nutritional quality improvement in common wheat.

Despite recent advances in crop metabolomics, the genetic control and molecular basis of wheat kernel metabolomes at different developmental stages remain largely unknown. Here, we performed a widely-targeted metabolic profiling in kernels at three developmental stages, namely grain filling kernels (FK), mature kernels (MK) and germinating kernels (GK), using a population of 159 recombinant inbred lines (RILs). A total of 625 annotated metabolites were detected, and 3173, 3143 and 2644 metabolite quantitative trait loci (mQTL) were mapped in FK, MK and GK, respectively. Only 52 mQTL were simultaneously mapped in all three stages, indicating a high stage-specificity of the wheat kernel metabolome. Subsequently, four candidate genes were functionally validated by in vitro enzymatic reactions and/ or transgenic approaches in wheat, with three of these mediating the tricin metabolic pathway. Meanwhile, both metabolite flux efficiencies within the tricin pathway and the superior candidate haplotypes were evaluated. Thus, the current work represents a comprehensive delineation of the pathway of tricin metabolism in wheat. Finally, further wheat metabolic pathways were re-constructed by updating them to incorporate the 177 candidates identified in the current study. To this end, our work not only provides new knowledge on wheat kernel metabolome variations, but also identifies important molecular resources for wheat nutritional quality improvement.