Identification of microRNAs and their targets responding to low-potassium stress in two barley genotypes differing in...

MicroRNAs (miRNAs) have diverse and crucial roles in plant growth and development, including in the response to abiotic stresses. Although plant responses to K deficiency are well documented at the physiological and transcriptional levels, the miRNA-mediated post-transcriptional pathways are still not clearly elucidated. In this study, high-throughput sequencing and degradome analysis were performed using two barley genotypes differing in low-K tolerance (XZ149, tolerant and ZD9, sensitive), to determine the genotypic difference in miRNAs profiling. A total of 270 miRNAs were detected in the roots of XZ149 and ZD9 at 2 d and 10 d after low-K treatment, of which 195 were commonly found in both genotypes. Their targets were further investigated by bioinformatics prediction and degradome sequencing approach. The results showed that ata-miR1432-5p might act as a regulator participating in Ca²⁺ signaling pathways in response to low-K stress. The difference in the miR444/MADS-box model as well as pathways mediated by miR319/TCP4 and miR396/GRF could be attributed to high tolerance to low-K stress in XZ149. In addition, other conserved and novel miRNAs families associated with low-K tolerance were also detected. The current results provide molecular evidence for understanding the possible involvement of miRNAs in the regulation of low-K tolerance.