Effects of Date Palm Waste Compost Application on Root Proteome Changes of Barley (Hordeum vulgare L.)

Proteomic analysis was performed to investigate the differentially abundant proteins (DAPs) in barley roots during the tillering stage. Bioinformatic tools were used to interpret the biological function, the pathway analysis and the visualisation of the network amongst the identified proteins. A total of 72 DAPs (33 upregulated and 39 downregulated) among a total of 2580 proteins were identified in response to compost treatment, suggesting multiple pathways of primary and secondary metabolism, such as carbohydrates and energy metabolism, phenylpropanoid pathway, glycolysis pathway, protein synthesis and degradation, redox homeostasis, RNA processing, stress response, cytoskeleton organisation, and phytohormone metabolic pathways. The expression of DAPs was further validated by qRT-PCR. The effects on barley plant development, such as the promotion of root growth and biomass increase, were associated with a change in energy metabolism and protein synthesis. The activation of enzymes involved in redox homeostasis and the regulation of stress response proteins suggest a protective effect of compost, consequently improving barley growth and stress acclimation through the reduction of the environmental impact of productive agriculture. Overall, these results may facilitate a better understanding of the molecular mechanism of compost-promoted plant growth and provide valuable information for the identification of critical genes/proteins in barley as potential targets of compost.