Identification of microRNAs in Caragana intermedia by high-throughput sequencing and expression analysis of 12 microRNAs and their targets under salt stress
MicroRNAs (miRNAs) are endogenous small RNAs that play important roles in various biological and metabolic processes in plants. Caragana intermedia is an important ecological and economic tree species that is prominent in the desert environment of west and northwest China. To date, no investigation into C. intermedia miRNAs has been reported. In this study, high-throughput sequencing of small RNAs was performed to identify both conserved and novel miRNAs, and also their target mRNA genes in C. intermedia. Based on sequence similarity and hairpin structure prediction, 132 putative conserved miRNAs (12 of which were confirmed to form hairpin precursors) belonging to 31 known miRNA families were identified. Ten novel miRNAs (including the miRNA* sequences of three novel miRNAs) were also discovered. The expression of 12 miRNAs was validated in different tissues, and the 12 miRNAs were further assessed by qRT-PCR after salt treatment. Furthermore, 36 potential target genes of 17 known miRNA families and two potential target genes of one novel miRNA were predicted, and some target genes were also assessed by qRT-PCR after salt treatment. Our study provides a basic catalog of miRNAs and their targets, which will promote further understanding of the important roles of miRNAs in C. intermedia and in other species of the leguminous genus, Caragana. Overall design: Examination of small RNA expression profiling in three-weeks-old seedings of Caragana intermedia.