Scientific Study

Post-harvest aflatoxin contamination is a challenging issue that affects peanut quality. Aflatoxin is produced by fungi belonging to the Aspergilli group, and is known as an acutely toxic, carcinogenic and immune-suppressing class of mycotoxins. Evidence for several host genetic factors that may impact aflatoxin contamination has been reported, e.g., genes for lipoxygenase (PnLOX1 and PnLOX2/PnLOX3 that showed either positive or negative regulation with Aspergillus infection), ROS, and WRKY (highly associated with or differentially expressed upon infection of maize with A. flavusAspergillus flavus between resistant (ICG 1471) and susceptible (Florida-07) cultivated peanut genotypes. The gene expression profiling analysis was designed to reveal differentially expressed genes in response to the infection (infected vs mock-treated seeds). In addition, the differential expression of the fungal genes was profiled. The study revealed the complexity of the interaction between the fungus and peanut seeds as expression of a large number of genes was altered including some in the process of plant defense to aflatoxin accumulation. Analysis of the experimental data with 'keggseq', a novel designed tool for KEGG enrichment analysis, showed the importance of alpha-linolenic acid metabolism, protein processing in endoplasmic reticulum, spliceosome, and carbon fixation and metabolism pathways in conditioning resistance to aflatoxin accumulation. In addition, co-expression network analysis was carried out to reveal the correlation of gene expression among peanut and fungal genes. The results showed the importance of WRKY, TIR-NBS-LRR, ethylene, and heat shock proteins in the resistance mechanism.