The chromatin accessibility landscape during early maize seed development

Cis-regulatory elements (CREs) are enriched in accessible chromatin regions (ACRs) of eukaryotes. Despite extensive research on genome-wide ACRs in various plant tissues, the global impact of these changes on developmental processes in maize seeds remains poorly understood. In this study, we employed the assay for transposase-accessible chromatin sequencing (ATAC-seq) to reveal the chromatin accessibility profile throughout the genome during the early stages of maize seed development. We identified a total of 37 952 to 59 887 high-quality ACRs in maize seeds at 0 to 8 days after pollination (DAP). Furthermore, we examined the correlation between the identified ACRs and gene expression. We observed a positive correlation between the open degree of promoter-ACRs and the expression of most genes. Moreover, we identified binding footprints of numerous transcription factors (TFs) within chromatin accessibility regions and revealed key TF families involved in different stages. Through the footprints of accessible chromatin regions, we predicted transcription factor regulatory networks during early maize embryo development. Additionally, we discovered that DNA sequence diversity was notably reduced at ACRs, yet trait-associated SNPs were more likely to be located within ACRs. We edited the ACR containing the trait-associated SNP of NKD1. Both NKD1^pro-1 and NKD1^pro-2 showed phenotypes corresponding to the trait-associated SNP. Our results suggest that alterations in chromatin accessibility play a crucial role in maize seed development and highlight the potential contribution of open chromatin regions to advancements in maize breeding.