Identification of copper (Cu) stress-responsive grapevine microRNAs and their target genes by high-throughput sequencing

MicroRNAs (miRNAs) are a class of single-stranded non-coding small RNAs (sRNAs) that are 20–24 nucleotides (nt) in length. Extensive studies have indicated that miRNAs play important roles in plant growth, development and stress responses. With more copper (Cu) and copper containing compounds used as bactericides and fungicides in plants, Cu stress has become one of the serious environmental problems that affect plant growth and development. In order to uncover the hidden response mechanisms of Cu stress, two small RNA libraries were constructed from Cu-treated and water-treated (Control) leaves of ‘Summer Black’ grapevine. Following high-throughput sequencing and filtering, a total of 158 known and 98 putative novel miRNAs were identified in the two libraries. Among these, 100 known and 47 novel miRNAs were identified as differentially expressed under Cu stress. Subsequently, the expression patterns of nine Cu-responsive miRNAs were validated by quantitative real-time PCR (qRT-PCR). There existed some co...