Small RNA profiling reveal regulation of microRNAs in field peanut pod rot pathogen infection

In recent years, the prevalence of peanut pod rot in northern China has increased, thereby severely threatening peanut yield and quality. The purpose of this study is to identify and analysis miRNAs during the process of peanut responding to pod rot, providing theoretical basis for improving the disease resistance of peanut by genetic engineering. The DNA libraries were diluted and quantified for sequencing through the Small RNA sequencing technology using Illumina HiSeq 2000. The raw reads were clean after quality trimming. The expression profiles of miRNAs were constructed and its target genes were analysis by quantitative real time PCR. The validation of miR156 targets were conducted by the 5’ RACE PCR. The present study identified 334 peanut miRNAs, of which 97 were down regulated and 27 were up regulated. The expression of 15 miRNAs was performed by qRT-PCR. Target gene prediction shown 1,998 target genes and 2,646 target loci were predicted for 303 miRNAs. A total of 152 target genes were predicted for the 119 differentially expressed miRNAs. Correlation analysis of transcriptome sequencing results identified 14 genes, which are regulated by 10 miRNAs. Negative regulatory relationships were observed between four miRNAs and their respective putative target genes. Many different miRNAs were involved in the molecular regulation of peanut responding to pod rot by negatively regulating target genes. These miRNAs showed different expression trends, the same miRNA might target multiple genes and have multiple target sites.