Abstract:

To explore the herbicidal mechanism of 4,8-dihydroxy-1-tetrahydronaphthone (4,8-DHT), this study carried out a weed seed germination experiment to assess the inhibitory effects of four concentrations of 4,8-DHT (0.5, 1.0, 2.5, and 5.0 mmol/L) on nine weed species (Lindernia procumbens, Eleusine indica, Salvia japonica, Taraxacum mongolicum, Avena fatua, Poa annua, Digitaria sanguinalis, Cynodon dactylon, Echinochloa crusgalli). In accordance with industry standards, representative weeds (L. procumbens and A. fatua) that meet germination rate criteria and sensitivity to 4,8-DHT were selected. Physiological-biochemical parameters analyses and transcriptomic profiling were employed to further reveal their potential mechanisms of action. The results demonstrated that high concentrations of 4,8-DHT (>2.5 mmol/L) significantly inhibited the seed germination of all nine tested weed species, and the inhibitory effect was concentration-dependent. At 5.0 mmol/L, 4,8-DHT exhibited inhibition rate of 89.9% and 86.3% for L. procumbens and A. fatua, respectively. The physiological-biochemical analyses revealed that as the concentration of 4,8-DHT increased, the activities of peroxidase (POD) and catalase (CAT) in the weeds exhibited a pattern of initially increasing and subsequently decreasing. Meanwhile, the levels of malondialdehyde (MDA) and proline (Pro) continuously increased, indicating that 4,8-DHT might impede the physiological activities of the weeds by interfering with the antioxidant defense system and the metabolism of osmotic regulatory substances. Transcriptomic analysis further disclosed that after treating L. procumbens with 4,8-DHT, a substantial number of differentially expressed genes were generated. Among these, the treatment group at 5 mmol/L (3295 genes) was significantly larger than that at 0.5 mmol/L (1858 genes), and these genes were mainly enriched in pathways including glutathione metabolism, glyoxylate and dicarboxylate metabolism, carbon fixation pathways, and plant-pathogen interactions. The research findings uncovered the potential mechanism by which 4,8-DHT inhibits the growth of weeds at the physiological-biochemical levels, offering scientific guidance for the development and practical application of 4,8-DHT as a novel plant-based herbicide.

Key words: 4,8-dihydroxy-1-tetrahydronaphthone, seed germination, physiological-biochemical parameters, transcriptomic profiling, functional mechanism