Protein Profiling of Arabidopsis Roots Treated With Humic Substances: Insights Into the Metabolic and Interactome Networks.

Sohaib Roomi,Tayyaba Yasmin,Silvia Quaggiotti,Paolo Carletti,Sara Trevisan,Micaela Pivato,Giorgio Arrigoni,Giovanni Battista Conselvan,Antonio Masi

doi:10.3389/fpls.2018.01812

Abstract

Background and Aim: Humic substances (HSs) influence the chemical and physical properties of the soil, and are also known to affect plant physiology and nutrient uptake. This study aimed to elucidate plant metabolic pathways and physiological processes influenced by HS activity.Methods: Arabidopsis roots were treated with HS for 8 h. Quantitative mass spectrometry-based proteomics analysis of root proteins was performed using the iTRAQ (Isobaric Tag for Relative and Absolute Quantification) technique. Out of 902 protein families identified and quantified for HS treated vs. untreated roots, 92 proteins had different relative content. Bioinformatic tools such as STRING, KEGG, IIS and Cytoscape were used to interpret the biological function, pathway analysis and visualization of network amongst the identified proteins.Results: From this analysis it was possible to evaluate that all of the identified proteins were functionally classified into several categories, mainly redox homeostasis, response to inorganic substances, energy metabolism, protein synthesis, cell trafficking, and division.Conclusion: In the present study an overview of the metabolic pathways most modified by HS biological activity is provided. Activation of enzymes of the glycolytic pathway and up regulation of ribosomal protein indicated a stimulation in energy metabolism and protein synthesis. Regulation of the enzymes involved in redox homeostasis suggest a pivotal role of reactive oxygen species in the signaling and modulation of HS-induced responses.

Highlights

Humic substances (HSs) are complex, heterogeneous, and widely distributed mixtures of organic compounds with different functional groups and molecular masses
Significant differences in morphological parameters were evidenced in HS treated Arabidopsis plants compared to control
The enhanced abundance of the abovementioned enzymes involved in glycolysis, pentose phosphate pathway, and tricarboxylic acid cycle (TCA) cycle due to HS may result in an increase in the production of NAD(P)H, ATP and carbon skeletons needed for various vital cellular processes such as biosynthesis of macromolecules, which, in turn may explain the known effect of HS on plant growth

Summary

Introduction

Humic substances (HSs) are complex, heterogeneous, and widely distributed mixtures of organic compounds with different functional groups and molecular masses. These compounds represent the end products of microbial decomposition and chemical degradation of dead biota and are considered the major components of soil organic matter (Nardi et al, 2002) and the most. HS can be used directly on plants at low concentrations (Aguiar et al, 2012) to enhance plant growth, yield and nutrient uptake For this reason, HS constitute a category of plant biostimulants as defined in du Jardin (2012) and Calvo et al (2014): studying plant responses to these compounds might have a broader impact, elucidating the effects of biostimulants in general. This study aimed to elucidate plant metabolic pathways and physiological processes influenced by HS activity

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Conclusion