Frontiers in plant science
Parasitism induces negative effects of clonal integration in the invasive plant Sphagneticola trilobata regardless of nutrient heterogeneity
By Wu TX, Zhang S, Xia J and 1 others.
Abstract
Introduction
Clonal integration typically enhances the fitness of clonal plants in heterogeneous resource environments, whereas it reduces fitness under parasitic stress. However, it remains unclear whether parasitic stress interacts with nutrient heterogeneity to affect the ecological effects of clonal integration.
Methods
We conducted a greenhouse pot experiment using the invasive clonal plant Sphagneticola trilobata, with or without one ramet parasitized by Cuscuta chinensis, and with or without severing the connection (allowing or preventing integration), under heterogeneous or homogeneous nutrient supply, combined with 15N tracing. Results and discussion: Our results showed that (1) compared with the severed treatment, the connection treatment significantly increased C. chinensis biomass and markedly decreased the biomass of connected but unparasitized ramets, but did not affect the biomass of directly parasitized ramets, ultimately leading to a significant decrease in the total biomass of clonal fragments of S. trilobata; (2) heterogeneous nutrient supply significantly intensified the detrimental effect of C. chinensis on parasitized ramets, but did not significantly affect connected unparasitized ramets; and (3) neither nutrient heterogeneity nor parasitism by C. chinensis affected the amount of 15N translocated among ramets. Collectively, these findings indicate that under parasitic stress, clonal integration has detrimental effects on plant fitness. Nutrient heterogeneity intensified the negative effects on parasitized ramets in poor patches but did not alter the detrimental effects on whole clonal fragments. Thus, C. chinensis suppresses S. trilobata consistently across nutrient conditions, supporting its potential as a biocontrol agent.