Clonal integration can promote the growth and spread of Alternanthera philoxeroides in cadmium-contaminated environments

Clonal plants are able to support the growth of their ramets in stressful environments via clonal integration between the ramets. However, it remains unclear whether the developmental status of stressed ramets affects the role of clonal integration. Here, we explored the effects of clonal integration at both the ramet level and the whole clonal fragment level when the apical ramets (younger) and basal ramets (older) were subjected to different concentrations of cadmium contamination. We grew pairs of ramets of Alternanthera philoxeroides, which were connected or disconnected by stolon between them. The apical and basal ramets were either uncontaminated or individually subjected to Cd contamination at concentrations of 5 mg kg(-1) and 50 mg kg(-1), respectively. Our results showed that clonal integration significantly promoted the growth of apical ramets subjected to Cd contamination. More importantly, under high Cd treatment, clonal integration also had a significant positive effect on the fitness of the whole clonal fragments. However, clonal integration did not affect plant growth when basal ramets were subjected to Cd contamination. Our study reveals the influence of the developmental status of stressed ramets on the role of clonal integration in heterogeneous heavy metal stress environments, suggesting that clonal integration may facilitate the spread of A. philoxeroides in Cd-contaminated habitats.

Automated summary

Clonal integration supports the growth of stressed ramets in Cd-contaminated environments, but its role may be influenced by the developmental status of the stressed ramets. This study found that clonal integration significantly enhanced the growth of apical ramets under Cd contamination and positively affected the fitness of the whole clonal fragments under high Cd treatment. However, clonal integration did not affect plant growth when basal ramets were subjected to Cd contamination. These findings highlight the importance of considering the developmental status of stressed ramets in understanding the role of clonal integration in heterogeneous heavy metal stress environments.