Location: Crop Genetics and Breeding ResearchTitle: Insight into genes regulating postharvest aflatoxin contamination of tetraploid peanut from transcriptional profiling
|KORANI, WALID - University Of Georgia|
|CHU, YE - University Of Georgia|
|Holbrook, Carl - Corley|
|OZIAS-AKINS, PEGGY - University Of Georgia|
Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2018
Publication Date: 5/15/2018
Citation: Korani, W., Chu, Y., Holbrook Jr, C.C., Ozias-Akins, P. 2018. Insight into genes regulating postharvest aflatoxin contamination of tetraploid peanut from transcriptional profiling. Genetics. 209:143-156.
Interpretive Summary: The objective of this study was to identify genetic factors and biochemical pathways that function to limit aflatoxin production in resistant peanut genotypes. Differential expression analysis revealed five important biochemical pathways regulating resistance. In addition, results captured the fungal pathways that are differentially affected by fungal infection and aflatoxin production on resistant vs. susceptible peanut genotypes. The study highlighted the critical role of the alpha-linoleic acid metabolism pathway and certain WRKY genes likely regulating the jasmonate-based defense pathways to mitigate aflatoxin production. To further estimate the effects of these components on aflatoxin production and/or identify QTL, we have created a population between ICG 1471 and Florida-07 that is being advance to recombinant inbred lines.
Technical Abstract: Postharvest aflatoxin contamination is a challenging issue that affects peanut quality. Aflatoxin is produced by fungi belonging to the Aspergillus group, and is known as a 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), reactive oxygen species, and WRKY (highly associated with or differentially expressed upon infection of maize with Aspergillus flavus); however, their roles remain unclear. Therefore, we conducted an RNA-sequencing experiment to differentiate gene response to the infection by A. 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 the 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 Kyoto Enclopedia of Genes and Genomes enrichment analysis, showed the importance of alpha-linoleic acid metabolism, protein processing in the endoplasmic reticulum, spliceosome, and carbon fixation and metabolism pathways in conditioning resistance to aflatoxin accumulation. In addition, coexpression network analysis was carried out to reveal the correlation of gene expression among peanut and fungal genes. The results showed the importance of WRKY, toll/Interleukin1 receptor-nucleotide binding site leucine-rich repeat (TIR-NBS-LRR), ethylene, and heat shock proteins in the resistance mechanism.