Thermopriming coupled to epigenetic regulation is revealed through nuclear proteome integrative analysis in Pinus radiata.

Abstract

How abiotic stresses affect nuclear proteomes and mediate memory effects? Despite the relevance of this question is capital in the present context of climate change, its answer remains unknown for most species. This work defines how Pinus radiata nuclei respond, adapt, remember and learn from heat stress. Seedlings were heat-stressed at 45 ºC in a 10-day-stress and recovery experiment. Nuclear proteins were isolated and quantified by nLC-MS/MS and tissue DNA methylation dynamics studied, and potential acquired memory was analyzed in recovered plants. A second heat-stress experiment was performed to validate stress memory effects and quantify expression of key genes. Specific nuclear heat responsive proteins were identified, and its biological role evaluated employing a systems biology approach. In addition to HSP, several clusters involved in regulation processes, as epigenomic-driven gene regulation, some transcription factors and a variety of RNA-associated functions were discovered. Nuclei exhibited differential proteome profiles across experiment, being notably H2A histone and methyl cycle enzymes accumulated at the recovery step. Thermopriming effect is possibly linked to H2A abundance and the overaccumulation of spliceosome elements in recovered Pinus radiata plants. Results suggest that epigenetic mechanisms are playing a key role in heat stress tolerance and priming mechanisms.