Date of Award
Spring 2024
Project Type
Thesis
Program or Major
Natural Resources
Degree Name
Master of Science
First Advisor
Serita D Frey
Second Advisor
Jessica Ernakovich
Third Advisor
Stuart Grandy
Abstract
Invasion of temperate forests by Alliaria petiolata (garlic mustard) may be affected by interactions with arbuscular mycorrhizal fungi (AMF). Although AMF are generally mutualists of land plants, they suppress the growth of close relatives of garlic mustard1–3. Garlic mustard produces indolic glucosinolates, a class of organic compounds known to suppress AMF4,5 and which may protect the plant from AMF antagonism. We would therefore expect a negative interaction between these organisms. Contrary to this expectation, we show that AMF inoculation promotes garlic mustard growth, and this effect is influenced by investments in plant defense. AMF inoculation and subsequent colonization increased plant growth in three geographically distinct garlic mustard populations, both in controlled laboratory conditions and in an in situ natural invasion. In contrast to typical arbuscular mycorrhizal symbioses, AMF did not produce arbuscules within garlic mustard roots where nutrient exchange occurs, but AMF inoculation did increase tissue N content and soil inorganic nitrogen availability. AMF inoculation also shifted glucosinolate production, with a strong negative correlation between glucosinolate production and plant growth. Our findings reveal a new phenotype of AMF symbiosis which lacks arbuscules but still promotes plant growth in the presence of an adjacent mycorrhizal symbiont. Prior assumptions that garlic mustard suppresses AMF are inadequate to explain the success of this invader since it clearly benefits from interactions with AMF. This study is the first to demonstrate simultaneous increases in plant biomass and tissue N with AMF inoculation in a mustard plant, with important implications for invasion biology and agriculture.
Recommended Citation
Trombley, Joshua A., "A Novel ‘Adjacent Mycorrhizal Symbiosis’ in Invasive Garlic Mustard" (2024). Master's Theses and Capstones. 1854.
https://scholars.unh.edu/thesis/1854