We previously showed that the synthesis of storage proteins is determined by the nitrogen availability per grain, through scaling laws independent of climatic conditions. The hypothesis we put forward is that these scaling laws are emerging properties of regulatory networks, notably of a transcriptional nature.
The synthesis of storage proteins is essentially regulated at the transcriptional level by the availability of assimilates. Several transcription factors (TFs) involved in this regulation have been identified and a certain number have already been cloned in wheat. However, the interactions between these TFs and storage proteins, and the pathways and mechanisms governing the transcriptional regulation of storage protein genes, are still very poorly understood. Similarly, the molecular mechanisms underlying the interactions between nitrogen and sulphur in the compensation phenomena between storage protein fractions have been very little studied. The development of functional genomics and bioinformatics tools now makes it possible to study these regulations in a global manner using a systemic approach that can link data obtained at several levels (mRNA, metabolites, enzymes, proteins, etc.) with a view to modelling, which implies:
1. identify and then model the underlying interaction networks and to link them to the ecophysiological model for nitrogen allocation in grain<
2. identify nodes (genes, metabolites, etc.) in these networks that enable modifications to the allocation laws governing protein nitrogen and sulphur allocation in grain
3. analyse the allelic variability of the genes associated with these regulatory nodes.