Ethylene‐responsive miRNAs in roots of Medicago truncatula identified by high‐throughput sequencing at the whole genome level

Ethylene is one of the classical plant hormones involved in regulation of numerous physiological processes ranging from seed germination and plant growth to fruit ripening and senescence. Emerging evidence indicates that microRNAs play important roles in regulation of plant growth, development, and hormonal signaling by affecting expression of target genes. To search for the role of microRNAs in mediation of ethylene-dependent inhibition of root elongation, we constructed two small RNA libraries from roots of the legume model plant Medicago truncatula treated with or without ACC and obtained more than 30 million raw reads by high-throughput sequencing. By mapping to the M. truncatula genome sequence and comparing to miRBase 16, we identified 291 and 270 known miRNAs in the control and ACC libraries and 2 new miRNAs. Based on bioinformatics analysis, we predicted the potential targets of the ethylene-responsive miRNAs. Further, the possible role of the ethylene-responsive miRNAs in the ethylene-induced inhibition of root elongation is discussed. These findings highlight important roles of miRNAs in mediation of ethylene-dependent physiological processes in general and root elongation in particular.