Conserved and novel heat stress-responsive microRNAs identified by deep sequencing in Pyropia yezoensis

Pyropia yezoensis is commonly known as a valuable marine red alga. As a cold-temperate species, high temperature is a critical abiotic stress factor that can affect the growth and development of this seaweed. Exploring the regulatory mechanisms of P. yezoensis resistance to high temperatures has significance in breeding high temperature-resistant strains. To investigate the potential role of microRNA (miRNA) regulation in heat stress, we constructed and sequenced four libraries (one control and three heat stressed). A total of 1213 miRNAs, corresponding to 174 miRNA families and 10 miRNAs precursors producing 14 novel mature miRNAs were identified. Among them, 98 miRNAs were differentially expressed under heat stress. The quantitative PCR of six selected miRNAs verified the deep sequencing data. This study represents the first set of heat-responsive miRNAs from P. yezoensis, and provides valuable information for understanding the miRNA-mediated heat stress responses and resistance mechanisms in P. yezoensis. The results offer a foundation for future studies on the genetic improvement of Pyropia heat stress tolerance.