Abstract:

【Objective】This experiment was conducted with the aim of defining changes in metabolic pathways in response to mandibulate insect feeding and providing references for the growth and protection of Chinese pine (Pinus tabuliformis).【Method】Pure P. tabuliformis forest in good growth status in Huangtuliangzi Forest Farm of Pingquan City, Chengde City, Hebei Province was the experimental field. Branches with consistent branch length and height above the ground in four directions were stimulated by ten pine caterpillars (Dendrolimus tabulaeformis) for feeding stimulation and leaf clipping control for mechanical damage. The pine needles were collected 3 cm below the chewing or cutting sites. The CK group received no treatment (0 h, recorded as 0 h), and 10 intact pine needles were collected. Metabolome and total flavonoid contents were measured in the needles at 0, 2 and 8 h after the different treatment modes. The plant hormones JA, SA, IAA and ABA were measured using needles at 0, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0, and 8.0 h after different treatments.【Result】Analysis of metabolomics showed that the top three pathways mainly annotated and enriched for DAMs compared to 2.0 h after FS and LCC are flavonoid biosynthesis, amino acid metabolism, and arginine and proline metabolism; the top three pathways mainly annotated and enriched for DAMs compared to 8.0 h after FS and LCC are flavonoid biosynthesis, linoleic acid metabolism, and flavonoid and flavonol biosynthesis. Thus, D. tabulaeformis feeding stimulation can significantly induce the upregulation of flavonoid expression at the chewing sites of needles when compared to the leaf clipping control. The plant hormones, JA and IAA, showed expression trends consistent with those of the corresponding substances in the metabolome. A significant positive correlation between JA and SA, JA and IAA and IAA and ABA (P< 0.05) was observed. 【Conclusion】Thus, the flavonoid pathway is one of the main pathways involved in resistant formation in conifers. Simple damage mechanisms did not induce significant differences in JA, IAA and ABA; thus, JA, IAA and ABA are involved in the development of resistance and growth during biotic stress.

Key words: Pinus tabuliformis, Dendrolimus tabulaeformis, feeding stimulation, induced resistant, plant hormone, flavonoid pathway, metabolome