Insight into Genes Regulating Postharvest Aflatoxin Contamination of Tetraploid Peanut from Transcriptional Profiling

Walid Korani; Ye Chu; C Corley Holbrook; Peggy Ozias-Akins

doi:10.1534/genetics.118.300478

Insight into Genes Regulating Postharvest Aflatoxin Contamination of Tetraploid Peanut from Transcriptional Profiling

Genetics. 2018 May;209(1):143-156. doi: 10.1534/genetics.118.300478. Epub 2018 Mar 15.

Authors

Walid Korani¹, Ye Chu¹, C Corley Holbrook², Peggy Ozias-Akins³

Affiliations

¹ Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, Georgia 31793.
² Crop Genetics and Breeding Research Unit, United States Department of Agriculture-Agricultural Research Service, Tifton, Georgia 31793.
³ Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Tifton, Georgia 31793 pozias@uga.edu.

Abstract

Postharvest 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), 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 Encyclopedia of Genes and Genomes enrichment analysis, showed the importance of α-linolenic 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.

Keywords: Aspergilli; Aspergillus flavus; KEGG enrichment analysis; aflatoxin; keggseq; peanut.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Aflatoxins*
Arachis / genetics*
Aspergillus flavus / growth & development
Aspergillus flavus / metabolism
Computational Biology / methods
Food Contamination*
Gene Expression Profiling*
Gene Expression Regulation, Plant*
Gene Ontology
Gene Regulatory Networks
Genotype
Reproducibility of Results
Tetraploidy*
Transcriptome*

Substances

Aflatoxins