The miRNA-mRNA regulatory networks of the response to NaHCO stress in industrial hemp (Cannabis sativa L.).

Background: Industrial hemp is an important industrial crop and has strong resistance to saline-alkaline stress. However, research on the industrial hemp response to NaHCO stress is limited. Therefore, the response mechanisms of industrial hemp under NaHCO stress were analysed through miRNA-mRNA regulatory networks.

Results: Seedlings of two salt-alkali tolerant and sensitive varieties were cultured in a solution containing 100 mM NaHCO and randomly sampled at 0, 6, 12, and 24 h. With prolonged NaHCO stress, the seedlings gradually withered, and the contents of jasmonic acid, lignin, trehalose, soluble protein, peroxidase, and superoxide dismutase in the roots increased significantly. The abscisic acid content decreased and then gradually increased. Overall, 18,215 mRNAs and 74 miRNAs were identified as differentially expressed under NaHCO stress. The network showed that 230 miRNA-mRNA interactions involved 16 miRNAs and 179 mRNAs, including some key hub novel mRNAs of these crucial pathways. Carbon metabolism, starch, sucrose metabolism, plant hormone signal transduction, and the spliceosome (SPL) were crucial pathways in industrial hemp's response to NaHCO stress.

Conclusions: It is speculated that industrial hemp can regulate SPL pathway by upregulating miRNAs such as novel_miR_179 and novel_miR_75, thus affecting starch and sucrose metabolism, plant hormone signal transduction and carbon metabolism and improving key physiological indices such as jasmonic acid content, trehalose content, and peroxidase and superoxide dismutase activities under NaHCO stress.