micro RNA s contribute to enhanced salt adaptation of the autopolyploid Hordeum bulbosum compared with its diploid ancestor

Summary Several studies have shown that autopolyploid can tolerate abiotic stresses better than its diploid ancestor. However, the underlying molecular mechanism is poorly known. micro RNA s (mi RNA s) are small RNA s that regulate the target gene expression post‐transcriptionally and play a critical role in the response to abiotic stresses. Duplication of the whole genome can result in the expansion of mi RNA families, and the innovative mi RNA –target interaction is important for adaptive responses to various environments. We identified new micro RNA s induced by genome duplication, that are also associated with stress response and the distinctive micro RNA networks in tetraploid and diploid Hordeum bulbosum using high‐throughput sequencing. Physiological results showed that autotetraploid Hordeum bulbosum tolerated salt stress better than its diploid. Comparison of mi RNA s expression between diploid and tetraploid check ( CK ) and salt stress revealed that five mi RNA s affected by genome doubling were also involved in salt stress response. Of these, miR528b‐3p was only detected in the tetraploid, and downregulated under salt stress relative to that in tetraploid CK . Moreover, through target prediction, it was found that miR528b‐3p was not only involved in DNA replication and repair but also participated in salt stress response. Finally, by analyzing all the differentially expressed micro RNA s and their targets, we also discovered distinguished micro RNA s–target regulatory networks in diploid and tetraploid, respectively. Overall, the results demonstrated the critical role of micro RNA s in autopolyploid to have better tolerance salt stress.