Identification and Expression Analysis of microRNAs in Response to Dormancy Release During Cold Storage of Lilium pumilum Bulbs

MicroRNAs (miRNAs) play important roles in post-transcriptional regulation as well as in various biological and metabolic processes. Lilium pumilum originated from northern China with a high ornamental value, and is important for Lilium resistance breeding. The dormancy of the bulbs has a serious effect on flowering quality. In this study, the miRNAs from samples at 0 days (S1 stage), 30 days (S2 stage), 60 days (S3 stage) and 90 days (S4 stage) of cold storage were sequenced to reveal the dormancy mechanism of Lilium pumilum. Through ultrastructural observation and physiological index measurement, we found that Lilium pumilum bulbs were released from dormancy during low-temperature storage. We further conducted miRNAs sequencing; a total of 17 conserved miRNAs were identified from 12 families, two nonconserved miRNAs were found that belonged to two families, and 38 novel miRNAs were predicted. MiRNA-target pairs analysis showed that some biological processes, including antioxidant reactions, epigenetic modification and abiotic stress, were induced in response to low-temperature conditions. Some transcription factors, plant hormone signalling pathways, and enzymes involved in plant growth and development were also activated to break the bulb dormancy. The study initially revealed the complex regulatory mechanisms of miRNAs for dormancy release during low-temperature storage. Comprehensive sequence information and target gene data were obtained by miRNAs sequencing, which determined that miRNAs regulation of bulb dormancy release in low temperature.