Human health is deeply rooted with the natural resources, which provide nutrition, and many current research emphasize in underpinning sustainable planetary health. With the socio-economic impacts of climatic drifts on the rise, the yield of nitrogen fixing legumes is being adversely affected by dehydration stress. Identifying the organelle-specific regulators for adapting to such environmental constraint would not only aid in understanding the molecular basis of stress-response, but developing fortified varieties (1). Nucleus (PM), designated as the cell’s control centre, hosts genetic information and regulates gene expression, we therefore aimed at understanding the dehydration-induced alterations in the expression patterns of the proteins and phosphoproteins hosted by the nucleus.
Four-week-old seedlings of a grain legume, chickpea, were subjected to gradual dehydration (2) and nuclear proteins (NPs) were extracted from unstressed control as well as from 72 and 144 h stressed tissues. Phosphopeptides were enriched by titanium-dioxide treatment followed by detection and relative quantification.
We identified 4832 NPs and 478 phosphosites, corresponding to 299 unique nuclear phosphoproteins (NPPs) involved in multivariate cellular processes including protein modification and regulation of gene expression, among others (3). The identified proteins included several novel kinases, phosphatases and transcription factors, besides 660 uncharacterised proteins. Spliceosome complex and splicing related proteins were dominant among differentially regulated NPPs, indicating their dehydration-modulated regulation. Phospho-motif analysis revealed stress-induced enrichment of proline-directed serine phosphorylation. Association mapping of NPPs revealed predominance of differential phosphorylation of spliceosome and splicing associated proteins. Also, regulatory proteins of key processes viz., protein degradation, regulation of flowering time and circadian clock were observed to undergo dehydration-induced dephosphorylation.
This inventory comprising several novel regulatory proteins and their precise sites of phosphorylation, would provide new insights into stress adaptation and enable directed genetic manipulations for developing climate-resilient crops.