Email: wolfram.weckwerth@univie.ac.at

The nutritional value of wheat grains, particularly their protein and metabolite composition, is a result of the grain-filling process, especially in the endosperm. Here, we employ tissue-specific sampling and laser microdissection (LMD) combined with shotgun proteomics and metabolomics to generate a tissue- and cell type-specific proteome and metabolome inventory of developing wheat endosperm at different grain-filling stages [1,2].

We identified altogether more than 15000 proteins from four different tissues and cell types seed coat, embryo, endosperm and cavity fluid, aleurone cells, sub-aleurone cells, starchy endosperm cells, and endosperm transfer cells.

Cell-type accumulation of specific SUT and GLUT transporters, sucrose converting and starch biosynthesis enzymes correlate well with the respective sugar metabolites, suggesting sugar upload and starch accumulation. Changes in various protein levels between AL, SA and ETC support this metabolic switch from 15 to 26 DAA.

The distinct spatial and temporal abundances of proteins and metabolites revealed a contrasting activity of nitrogen assimilation pathways, e.g. for GOGAT, GDH and glutamic acid, in the different cell types from 15 to 26 DAA, which can be correlated with specific protein accumulation in the endosperm.

The integration of cell-type specific proteome and metabolome data revealed a complex metabolic interplay of the different cell types and a functional switch during grain development and grain-filling processes.

Zhang, S., Ghatak, A., Bazargani, M. M., Bajaj, P., Varshney, R. K., Chaturvedi, P., Jiang, D. & Weckwerth, W. Spatial distribution of proteins and metabolites in developing wheat grain and their differential regulatory response during the grain filling process. Plant J 107, 669-687, doi:10.1111/tpj.15410 (2021).

Zhang, S., Ghatak, A., Mohammadi Bazargani, M., Kramml, H., Zang, F., Gao, S., Ramsak, Z., Gruden, K., Varshney, R. K., Jiang, D., Chaturvedi, P. & Weckwerth, W. Cell-type proteomic and metabolomic resolution of early and late grain filling stages of wheat endosperm. Plant Biotechnol J, doi:10.1111/pbi.14203 (2023).