Auxin signalling activation and flavonoid metabolic dynamics in mowing Leymus chinensis

While mowing imposes mechanical stress on Leymus chinensis, moderate mowing intensity paradoxically enhances its regrowth capacity. We aimed to elucidate how L. chinensis orchestrates its defence response at the molecular level. We conducted integrated transcriptomic and metabolomic profiling to identify key changes in gene expression and metabolite levels. Our focus was on the modulation of flavonoid biosynthesis and phytohormone signalling pathways, which are crucial for stress adaptation. Our analyses revealed significant modulation in flavonoid biosynthesis, which is known for its role in plant defence mechanisms. Additionally, we observed changes in phytohormone signalling pathways that are essential for growth regulation and stress response. Characterization of the Aux/IAA gene family identified LcIAA3 as a key player in the mowing stress response, with its expression consistently upregulated. The modulation of flavonoid biosynthesis and phytohormone signalling pathways under moderate mowing intensity is central to L. chinensis's enhanced regrowth. LcIAA3, which is upregulated post-mowing, is likely involved in these processes and may be a significant factor in the plant's stress response. Further functional validation is necessary to confirm its role. Our study provides valuable insights into the molecular mechanisms of mowing tolerance and potential breeding targets for improving the resilience of forage crops under moderate mowing conditions.