Overexpression of Lol-miR11467 negatively affects osmotic resistance in Larix kaempferi 3 × L. gmelinii 9

Background Larch (Larix gmelinii (Rupr.) Kuzen.) is an important timber and ecological tree species in northern China. Excellent germplasm resources have been acquired through time-consuming traditional breeding. Molecular breeding offers a promising approach to shorten the breeding cycle and achieve genetic improvements more efficiently. MicroRNAs (miRNAs) are non-coding, single-stranded small RNAs that primarily affect plant growth and stress resistance, including drought stress. However, the study of miRNAs in larch under drought stress has not been well explored. Results In this study, to investigate the function of Lol-miR11467 under PEG osmotic stress in larch, embryogenic callus tissue of Larix kaempferi 3 × L. gmelinii 9 was employed as the experimental material, serving as the explants for this study. Lol-miR11467was transferred into the explants using an Agrobacterium-mediated method to determine the physiological changes and survey gene expression changes in overexpressing Lol-miR11467 cell lines. The results showed that the fresh weight, peroxidase (POD), soluble protein and soluble sugar content of the overexpressing Lol-miR11467 were lower than that of the wild-type, while malondialdehyde (MDA) content increased under PEG osmoticstress. Transcriptome analysis showed that genes associated with phenylpropanoid metabolism, transcription factors, oxidoreductase, plant hormone signal transduction, glucose metabolism and bioprotective macromolecules were mainly downregulated in Lol-miR11467 cell lines. Conclusions Overall, these results indicated that the drought resistance of the overexpressing Lol-miR11467 cell lines was reduced. This study'sfindings might provide a foundation for understanding the molecular mechanisms of miRNAs under PEG osmotic stress in larch, potentially contributing to the development of strategies for improving plant resilience to environmental stresses.