Biogeographic differences in the allelopathy of leaf surface extracts of an invasive weed

IRIMIA RE; LOPES SMM; SOTES GJ; CAVIERES LA; EREN Ö; LORTIE CJ; FRENCH K; HIERRO J; ROSCHE C; CALLAWAY RM; PINHO E MELO TMVD; MONTESINOS D

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2019 vol. 21 p. 3151 - 3168

1387-3547

Allelopathy, the release of chemicals by plants that inhibit thegermination and growth of competing species, can be an important trait for invasivesuccess. However, little is known about potential biogeographical differencesin allelopathy due to divergent regional eco-evolutionary histories. To testthis, we examined the allelochemical potential of the highly invasive species Centaureasolstitialis from six world regions including native (Spain, Turkey) andnon-native ranges (Argentina, Chile, California and Australia). Seeds fromseveral populations in each region were collected and grown under common gardenconditions. Allelopathic potential and chemical composition of three leafextract concentrations of C. solstitialis from each region: 0.25%, 0.5%, 0.75%(w/v-1) were assessed on the phytometer Lactuca sativa. The mainallelochemicals present in the leaf-surface extract were sesquiterpene lactonesthat varied in major constitutive compounds across regions. These leaf extractshad strong inhibitory effects on L. sativa seed germination and net growth. Summedacross regions, the 0.25% concentration suppressed germination by 72% andradicle elongation by 66%, relative to the controls. At the 0.5% concentration,no seeds germinated when exposed to extracts from the non-native ranges ofArgentina and Chile, whereas germination and radicle growth were reduced by 98%and 89%, respectively, in the remaining regions, relative to controls.Germination and seedling growth were completely inhibited at the 0.75%concentration extract for all regions. Some nonnative regions werecharacterized by relatively lower concentrations of allelochemicals, suggestingthat there is biogeographical variation in allelopathic expression. Thesefindings imply that rapid selection on the biochemical signatures of an exoticinvasive plant species can be highly region-specific across the world.