Arbuscular mycorrhizal fungi improve the adaptation of a high-latitude population of the invasive plant Wedelia trilobata to low-temperature stress

Abstract:

[Background] The invasive plant Wedelia trilobata presents wide distribution in southern China and a trend of expanding towards the north. Arbuscular mycorrhizal fungi (AMF) play a significant role in plant growth and responses to environmental stress. However, the role of AMF in the population expansion of W. trilobata and the adaptation of this plant to low-temperature stress remains unclear. [Objective] To investigate the role of AMF in the low-temperature stress responses of the Wenzhou and Sanya populations of W. trilobata, explaining the northward expansion of W. trilobata populations from the perspective of symbiotic microorganisms. [Methods] We selected stem segments of the Sanya and Wenzhou populations of W. trilobata from the southernmost and northernmost regions, respectively, of its current distribution in China, and used the stem segments of the native species W. chinensis as the control. We conducted a controlled pot experiment. The experiment was designed with inoculation of the AMF strain Rhizophagus intraradices and simulated low-temperature treatment. By analyzing the AMF colonization indices and the growth and physiological indices of plants from different populations, we explored the role of AMF in the adaptation of different populations of W. trilobata to low temperatures. [Results] AMF significantly enhanced the aboveground and belowground biomass of the Wenzhou and Sanya populations of W. trilobata at normal temperatures. Furthermore, AMF significantly increased the belowground biomass of the Wenzhou population at low temperatures. Meanwhile, the inoculation of AMF significantly improved the maximal photochemistry efficiency while significantly reducing the content of flavonols in the Wenzhou population at low temperatures. [Conclusion] AMF significantly promoted the growth of W. trilobata and significantly enhanced the tolerance of the high-latitude population to low temperatures. Therefore, we found that symbiosis with AMF may be one of the important microbial factors for the norward expansion of W. trilobata populations.