Aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) are the most common aflatoxins produced by Aspergillus flavus in peanuts, with high carcinogenicity and teratogenicity. Identification of DNA markers associated with resistance to aflatoxin production is likely to offer breeders efficient tools to develop resistant cultivars through molecular breeding. In this study, seeds of 99 accessions of a Chinese peanut mini-mini core collection were investigated for their reaction to aflatoxin production by a laboratory kernel inoculation assay. Two resistant accessions (Zh.h0551 and Zh.h2150) were identified, with their aflatoxin content being 8.11%–18.90% of the susceptible control. The 99 peanut accessions were also genotyped by restriction site-associated DNA sequencing (RAD-Seq) for a genome-wide association study (GWAS). A total of 60 SNP (single nucleotide polymorphism) markers associated with aflatoxin production were detected, and they explained 16.87%–31.70% of phenotypic variation (PVE), with SNP02686 and SNP19994 possessing 31.70% and 28.91% PVE, respectively. Aflatoxin contents of accessions with “AG” (existed in Zh.h0551 and Zh.h2150) and “GG” genotypes of either SNP19994 or SNP02686 were significantly lower than that of “AA” genotypes in the mean value of a three-year assay. The resistant accessions and molecular markers identified in this study are likely to be helpful for deployment in aflatoxin resistance breeding in peanuts.

Histone methylation and acetylation play potential roles in plant growth and development through various histone modification (HM) genes. However, studies of HM genes are still limited in peanut (Arachis hypogaea L.), a globally important oilseed crop. Here, comprehensive identification and investigation of HM genes were performed using the whole genome of peanut, and a total of 207 AhHMs encoding 108 histone methyltransferases, 51 histone demethylases, 16 histone acetylases, and 32 histone deacetylases were identified. Detailed analysis of these AhHMs, including chromosome locations, gene structures, protein motifs, and protein–protein interactions, was performed. Tandem, segmental, transposed, dispersed, and whole-genome duplications were involved in the evolution and expansion of the HM gene families in peanut. Ka/Ks analysis indicated that the AhHMs underwent purifying selection. The expression profiles of the 207 AhHMs were investigated during the pod and seed development stages on the basis of the transcriptome sequencing results. Quantitative real-time PCR confirmed that eight AhHMs were differentially expressed during pod and seed development. These results provide data support for further studying the epigenetic mechanism of peanut histones, deepen the understanding of seed development, and provide a new direction for the cultivation of more high-yield and high-quality peanut varieties.