Transcriptomic effects of Aspergillus alliaceus on Orobanche during its pathogenesis

Abstract

The aim of this study was to investigate the pathogenicity of Aspergillus alliaceus (Aa), a fungal biocontrol agent, on Orobanche by transcriptomic tests. For this reason, the expression of several genes was analysed comparatively in the experimental (fungi applied) and control (fungi-free) groups. After fungal infection, the expression of antioxidant enzyme genes SOD (Mn-superoxide dismutase), CAT (catalase), and SOD2 (Zn-superoxide dismutase) and the genes GS (Glutamine synthetase), HSP70 (heat-shock protein), and apoptosis [BCL2, BAX, caspase3 (CASP3)], which are related to protein metabolism, were investigated in the both groups. In gene expression studies, gene expression of SOD was almost 2.5 times higher in the experimental group than in the control group (fungus-free, intact), while the expression levels of other antioxidant genes (CAT and SOD2) were significantly reduced. While GS, which is the N and protein metabolism balancer, was found to be relatively low as compared to the control group, however, the level of HSP70 (protein folding, chaperoning) was quite higher than the control. Gene expressions of all apoptotic genes, BAX (=apoptosis suppressive gene), CASP3 and BCL (=apoptosis inducer genes), were significantly lower than control group. All the results found for the control group were determined to be statistically significant. It was concluded that during Aa pathogenesis, (1) the increased SOD value was associated with ROS (reactive oxygen species) threats, (2) the fungi disturbed protein synthesis metabolism, and finally, (3) the inhibited antioxidant and apoptosis-based pathways compared to the control group. These conclusions were discussed in the light of slow but constantly lethal effects of Aa comparatively to other pathogenic fungus, Fusarium.