Data for: Soil microbiota explain differences in herbivore resistance between native and invasive populations of a perennial herb

Soil microbiota can either slow down or facilitate plant invasions through
their effects on plant performance. Associations with soil microbiota can
also modify other plant traits such as herbivore resistance, which can
indirectly affect the outcome of plant introductions. We studied the
effects of soil microbiota on the perennial herbaceous legume Lupinus
polyphyllus that hosts nitrogen-fixing mutualistic bacteria. We compared
the plant performance, herbivore resistance, and volatile organic
compounds (VOCs) of plants from native (North American) and invasive
(Finnish) populations of the species that were inoculated with intact or
autoclaved soil from an invasive population. We found that plants of both
origins greatly benefited from the intact soil inoculum with respect to
all performance measures considered, suggesting that beneficial
nitrogen-fixing rhizobia in the soil play a major role in shaping plant
phenotypes. For three traits, effects of the intact soil inoculum were
stronger in plants of native origin than in plants of invasive origin
(number of leaves, herbivore resistance, and total biomass). With the
intact soil inoculum, plants of invasive origin were more resistant to
snails than plants of native origin. Strikingly, differences in resistance
to snails between plants of different origins disappeared entirely when
soil microbes were reduced. Soil inoculum treatment altered the
composition of the leaf VOC bouquet similarly regardless of plant origin.
Synthesis: These results demonstrate the ability of L. polyphyllus to
associate with and benefit from putatively novel soil microbiota including
rhizobia, which has likely contributed to its invasion success.
Furthermore, it appears that the invasive populations have adapted to be
less reliant on their symbionts, which further facilitates species spread.
To our knowledge, this is the first study to demonstrate that differences
in herbivore resistance between native and invasive plant populations of
the same species can depend entirely on soil microbiota.