Proteomic Profiling and Protein-Protein Interaction Network Reveal the Molecular Mechanisms of Susceptibility to Drought Stress in Canola (Brassica napus L.) Reza Shokri-Gharelo 1 , Ali Bandehagh 1,* and Mohammad Anwar Hossain 2,* 1 Department of Plant Breeding and Biotechnology, University of Tabriz, Tabriz, 51368, Iran 2 Department of Genetics and Plant Breeding, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh * Corresponding Authors: Ali Bandehagh. Email: bandehhagh@tabrizu.ac.ir; Mohammad Anwar Hossain. Email: anwargpb@bau.edu.bd Received: 23 November 2021 Accepted: 17 January 2022 ABSTRACT Drought stress is one of the most important abiotic stresses that plants face frequently in nature. Under drought conditions, many morphological, physiological, and molecular aspects of plants are changed and as a result plants experience a remarkable reduction in growth, yield, and reproduction. To expand our understanding of the mole- cular basis of the plant response to drought stress, the proteomic profile and protein-protein network of canola (Brassica napus L.) were studied. The focus was to show molecular mechanisms related to canola susceptibility to drought stress. The experiment used a completely randomized design, implemented in a hydroponic system under greenhouse conditions. To impose drought stress, plants were exposed to Hoagland’ s solution supplemented with polyethylene glycol (PEG) 6000 for 7 days. The drought stress resulted in 161reproducible protein spots in two- dimensional electrophoresis of canola leaves. The t-student test showed 21 differentially abundant proteins (DAP), of which 2 and 19 were up and down accumulated, respectively. Two spots identified as 1-aminocyclopro- pane-1-carboxylate oxidase and D-2-hydroxyglutarate dehydrogenase showed an increased abundance of 2.11 and 1.77, respectively. The extended protein-protein interaction of differentially abundant proteins and KEGG analysis showed 47 pathways directly and indirectly associated with canola response to drought stress. DAPs with increased abundance were associated with amino acid and signaling processes, whereas DAPs with decreased abundance were mostly connected with pathways responsible for energy production. The results of the study will help to elucidate further the molecular events associated with the susceptibility to drought stress in canola. KEYWORDS Abiotic stress; differentially abundant protein; molecular function; proteomics; susceptibility 1 Introduction The challenges of abiotic stress have widely been under attention as one of the major constraints to crop production. On the other hand, increasing human population and demand for more food exacerbate these challenges alongside other constraints such as climate change and biotic stress [1]. These challenges to secure food production for the world demand crops which are resilient to such conditions [1]. Genetic engineering of crops to make them more tolerant to unfavorable conditions has been considered as one of the strategies to secure food production around the world [2]. However, a complexity of mechanisms This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. DOI: 10.32604/phyton.2022.020431 ARTICLE ech T Press Science