Clonal Integration between Zoysia Ramets Improves Overall Resistance under Heterogeneous Pb and/or Pyrene Stresses by Modulating AsA-GSH Cycle

Abstract

Pb and Pyrene, prevalent in soil, significantly affect plants. Ascorbate-glutathione (AsA-GSH) cycle is crucial for plant antioxidant defense mechanisms. Understanding the clonal integration of clonal plants in heterogeneous contaminated soil is important. This work investigates the potential effects of clonal integration on the key players in specifically the metabolism, AsA-GSH cycle, in Zoysia japonica ramets under three heterogeneous stresses (Pb and/or Pyrene) and two stolon connection statuses (connected and disconnected ramets). The results showed that connected stressed ramets exhibit higher biomass accumulation and lower H2O2 content compared to disconnected stressed ramets. This can be attributed to the enhancement of Ascorbate Peroxidase (APX) enzyme activity, the preservation of Glutathione Reductase (GR), Dehydroascorbate Reductase (DHAR), and Monodehydroascorbate Reductase (MDHAR) activity. Furthermore, there was a reduction in the decline of Ascorbic Acid (AsA) and Glutathione (GSH), and a decrease in the rise of Dehydroascorbic Acid (DHA) and Glutathione Disulfide (GSSG). Among three heterogeneous stresses, clonal integration performs better under Pb or Pyrene stress than under Pb + Pyrene stress. Our study highlights the vital role of clonal integration in maintaining redox balance and supporting the success of clonal plants in toxic environments, even under severe combined stress.