Allelochemicals of the invasive tree species Senna spectabilis alleviate antioxidant enzyme activities in native plants of Western Ghats.

Invasive alien species are major threats to biodiversity worldwide. Senna spectabilis is one such species that has been introduced to several countries, including India. This study aimed to investigate the allelopathic potential of aqueous extract of leaves of Senna spectabilis on native plants. For these five native plant seedlings (Ailanthus tryphysa (AT), Pongamia pinnata (PP), Tectona grandis, Hopea parviflora (HP), and Dendrocalamus strictus (DS)) of 6 months old were root fed with leaf extract of S. spectabilis for 3 years. Assays such as metabolic activity, L-proline estimation, lipid peroxidation and antioxidant enzymes (Superoxide dismutase, Catalase, Ascorbate peroxidase and Polyphenol oxidase) were used to assess the allelopathic potential of S. spectabilis, and finally, bioactive phytochemical compounds like Neophytadiene, Nerolidol, 2,4-Ditert-Butylphenol etc. were identified by gas chromatography coupled with mass spectrometry (GC–MS). The effects of S. spectabilis extracts highly varied depending on the native species and the variable measured. Regarding antioxidant enzyme activities of the native species, APX and CAT were generally higher in AT and HP, independently of the treatment with S. spectabilis extracts. However, SOD of AT and PP clearly increased as the concentration of the S. spectabilis extracts increased. In general, S. spectabilis extracts tend to increase formazan content of HP and DS and proline content of PP. GC‒MS analysis detected 28 phytoconstituents in the S. spectabilis leaf extracts and 7 plant allelochemicals were identified, including phenolic compounds, fatty acids, and terpenoids. These findings suggest that S. spectabilis has strong allelopathic potential, which could contribute to its invasive potential. The present study highlights the need for effective management strategies to control the spread of this invasive species and the importance of selecting specific native species for restoration programs. [ABSTRACT FROM AUTHOR]