Omics Data Reveal Putative Regulators of Einkorn Grain Protein Composition under Sulphur deficiency.

Understanding the molecular mechanisms controlling the accumulation of grain storage proteins in response to nitrogen (N) and sulphur (S) nutrition is essential to improve cereal grain nutritional and functional properties. Here, we studied the grain transcriptome and metabolome responses to post-anthesis N and S supply for the diploid wheat einkorn (Triticum monococcum). During grain filling, 848 transcripts and 24 metabolites were differentially accumulated in response to N and S availability. Total free amino acids per grain and 241 transcripts showed significant modifications of their accumulation profile during most of the grain filling period and were upregulated in response to S-deficiency. Among them, 24 transcripts strongly responded to S-deficiency and were identified in co-expression network analyses as potential coordinators of the grain response to N and S supply. Sulphate transporters and genes involved in sulphate and methionine metabolisms were activated, probably to regulate the pool of free amino-acids necessary for grain storage protein (GSP) synthesis and to limit the impact of S-deficiency on the accumulation of GSPs.