Identifying changes in the wheat kernel proteome under heat stress using iTRAQ

Wheat (Triticum aestivum L.) is one of the three major global food crops. High-temperature stress can affect its yield and quality. Studies of the effect of high-temperature stress on wheat kernel development are important because they can reveal the stability of wheat quality and lead to the genetic improvement of wheat quality traits. In this study, the isobaric tags for relative and absolute quantitation (iTRAQ) method was adopted to analyze changes in the protein expression profile of wheat cultivars under high temperature stress. The protein content of wheat grain increased under heat stress, while the SDS-sedimentation value and starch content decreased. Grain filling was deficient under high temperature stress, which reduced thousand-kernel weight but did not affect wheat kernel length. The 207 differentially expressed proteins identified in Gaocheng 8901 under heat stress were associated with energy metabolism, growth and development, and stress response. Gene Ontology enrichment analysis showed that the annotated proteins that were differentially expressed in Gaocheng 8901 under heat stress were involved mainly in stimulus response, abiotic stress response, stress response, and plasma membrane. A set of 78 differentially expressed proteins were assigned to 83 KEGG signaling/metabolic pathways. KEGG pathway enrichment analysis showed that this set of proteins was significantly enriched in members of 51 pathways, and the proteins participated mainly in protein synthesis in the endoplasmic reticulum, starch and sucrose metabolism, and reaction on ribosomes. Five differentially expressed proteins were involved in protein–protein interaction networks that may greatly influence the yield and quality of wheat grain. In wheat, high-temperature stress leads to a variety of effects on protein expression and may ultimately cause changes in yield and quality. Keywords: Winter wheat, Heat stress, GO enrichment, KEGG pathway enrichment, Interaction networks