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

Abstract

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.

Keywords: barley; compost; differentially abundant proteins; proteome; qRT-PCR; roots.

Figure 1

Morphological effects of date palm waste compost in shoots and roots of barley plants. Scale bars: 5 cm.

Figure 2

Functional categories and subcellular localization of DAPs from roots: subcellular localization (a), molecular function (b), biological process (c) and protein class (d).

Figure 3

KEGG pathway enrichment of DAPs induced by date palm waste compost in barley roots.

Figure 4

Confirmation of proteomic results by quantitative real-time PCR (qRT-PCR). The white and black bars represent fold change of mRNA and protein abundances in barley roots, respectively.

Figure 5

Analysis for protein-protein (PPI) interaction network for the DAPs. The different line colours represent the types of evidence used in predicting the associations: neighbourhood (green), co-occurrence across genomes (blue), co-expression (black), experimental (purple) and association in curated databases (light blue) or texting (yellow). Disconnected nodes or proteins not connected to the main network were hidden in the network.

Figure 6

A model of date palm waste compost effects on barley plants.