Application of methyl jasmonate reduces growth but increases chemical defence and resistance againstHylobius abietisin Scots pine seedlings.

Scots pine (Pinus sylvestrisL., Pinaceae) produces a terpenoid resin which consists of monoterpenes and resin acids that offer protection against herbivores and pathogen attacks. Methyl jasmonate (MJ) is a potential plant elicitor which induces a wide range of chemical and anatomical defence reactions in conifers and might be used to increase resistance against biotic damage. Different amounts of MJ (control, 10 mm, and 100 mm) were applied to Scots pine to examine the vigour, physiology, herbivory performance, and induction of secondary compound production in needles, bark, and xylem of 2-year-old Scots pine seedlings. Growth decreased significantly in both MJ treated plants, and photosynthesis decreased in the 100 mmMJ treated plants, when compared to 10 mmMJ or control plants. The large pine weevil (Hylobius abietisL.) (Coleoptera: Curculionidae) gnawed a significantly smaller area of stem bark in the 100 mmtreated plants than in the control or 10 mmtreated plants. The 100 mmMJ treatment increased the resin acid concentration in the needles and xylem but not in the bark. Furthermore, both MJ treatments increased the number of resin ducts in newly developing xylem. The changes in plant growth and chemical parameters after the MJ treatments indicate shifts in carbon allocation, but MJ also affects plant physiology and xylem development. Terpenoid resin production was tissue-specific, but generally increased after MJ treatments, which means that this compound may offer potential protection of conifers against herbivores. [ABSTRACT FROM AUTHOR]