Different benefit from clonal integration of stress signal between a stoloniferous alien invasive plant and its congeneric native one

Under heterogeneous resource supply, alien invasive plants with clonal growth can benefit more from clonal integration than their native ones. However, different benefit from translocation of non-resource substance (such as stress signal or hormone) between invasive alien clonal plants and native congener remains poorly understood. To address this, we conducted a pot experiment to explore translocation of stress signal, induced by local exogenous abscisic acid (ABA) application, within clonal networks of alien invasive plant Wedelia trilobata and native congeners W. chinensis subjected to drought stress (20 % soil moisture). In W. trilobata, chlorophyll fluorescence parameters (F_v/F_m, ΦPSII and qP) and photosynthetic parameters (P_n and G_s) of young ramets significantly increased 2–3 days after ABA application to old ramets. In contrast, W. chinensis exhibited a delayed response, with a significant increase in F_v/F_m of young ramets observed only after 3 days, and increases in P_n and G_s delayed until 17 days. A similar temporal difference was observed when ABA was applied to young ramets; chlorophyll fluorescence and photosynthetic parameters in old ramets of W. trilobata responded more rapidly than those in W. chinensis. At the end of experiment, exogenous ABA application significantly promoted biomass accumulation in alien invasive plant W. trilobata, but had no significant effect on the W. chinensis. It is suggested that translocation of stress signal may improve growth performance more in invasive alien clonal plant than its native congeners. Consequently, translocation of stress signal may confer a competitive advantage to invasive alien clonal plants over native plants, further contributing to its invasiveness.