Identification And Differential Expression Analysis Of MicroRNAs Under Cold Stress In Populus Tomentosa

Populus tomentosa Carr.(Chinese white poplar) is a native specie in section Leuce with fast-growing and high wood quality in northern China. Cold stress is one of the most common abiotic factors affecting plants, and it adversely affects plant growth, development, and spatial distribution. MicroRNAs (miRNAs) are small, non-coding RNAs that regulate the expression of target mRNAs in plant growth, development, abiotic stress responses, and pathogen responses. To understand the roles of microRNAs under cold stress in Populus tomentosa, we constructed two small RNA libraries from plants treated or not treated with cold stress (4℃for8h). High-throughput sequencing of the two libraries identified144conserved microRNAs belonging to33microRNA famicrolies and29new microRNAs (as well as their corresponding microRNA*s) belonging to23microRNA families.19cold-responsive microRNAs, two new microRNAs and their corresponding microRNA*s were validated by qRT-PCR. A total of101target genes of the new microRNAs were predicted using a bioinformatics approach. These target genes are involved in growth and resistance to various stresses. The results demonstrated that Populus microRNAs play critical roles in the cold stress response.