Using isobaric tags for relative and absolute quantification(iTRAQ) and associated analytic technologies,we have cataloged and compared 7 069 unique wheat proteins expressed during four substages of the filling stage. Among them,859 are differentially expressed,showing at least a 2-fold difference in concentration across substages. Differentially expressed proteins(DEPs) includind high-molecular weight glutenin subunit(W5 AIU1),low-molecular weight glutenin subunit(Q8 W3 V4),gliadin/avenin-like seed protein(D2 KFG9),and avenin-like protein(W5 DVL2),all of which have previously been identified as important for nutritional quality and bread-making properties,and all of which were found to increase at the latter stages of development. We have applied statistical techniques to group the proteins into hierarchical clusters,and have consulted databases to infer functional and other relationships among the identified proteins. Using isobaric tags for relative and absolute quantification (iTRAQ) and associated analytic technologies, we have cataloged and compared 7 069 unique wheat proteins expressed during four substages of the filling stage. Among them, 859 are differentially expressed, showing at least a 2-fold Differentially expressed proteins (DEPs) includind high-molecular weight glutenin subunit (W5 AIU1), low-molecular weight glutenin subunit (Q8 W3 V4), gliadin / avenin-like seed protein (D2 KFG9), and avenin -like protein (W5 DVL2), all of which have previously been identified as important for nutritional quality and bread-making properties, and all of which were found to increase at the latter stages of development. We have applied statistical techniques to group the proteins into hierarchical clusters, and have consulted databases to infer functional and other relationships among the identified proteins.