D3440: Growth and defense responses to herbivory cues in a woody plant species

In plants expression of resistance through development of various physical and chemical defense traits in response to herbivory is well-documented. In addition, plants may also respond to herbivory through compensatory growth, a relatively less studied mechanism. Compensatory growth is especially important in seedlings in which defense traits are still developing and leaf area is critical to future growth potential. Here we investigated how sugar maple, Acer saccharum seedlings respond to three different herbivory treatments (water control, slug mucus and methyl jasmonate (MJ)). There is increasing evidence that mucus cues can alter plant growth and defense traits.

Beginning 4 weeks post emergence, seedlings were treated every 3^rd day (5 times) with water, locomotion mucus of Arion subfuscus or MJ. Plant responses were followed for 88 days. At 3- days post treatment, MJ seedlings had fewer leaves, less leaf area, and total biomass compared to control seedlings. However, growth did not differ between MJ and control treatments 88 days post treatment indicating compensatory growth in MJ treated seedlings. Moreover, mucus and water treated seedlings did not initially differ in growth, but at day 88- post treatment aboveground biomass of mucus treated seedlings was higher than control suggesting overcompensation. Plant chemistry analysis and herbivore bioassays are underway.