Transcriptome Analysis of Populus tomentosa Reveals Molecular Mechanisms of Jasmonate Signaling Pathway on Arsenic Tolerance Induced by Arbuscular Mycorrhizal Fungi

Abstract

Simple Summary Arsenic (As) contamination represents a global soil-pollution issue that impairs plant growth and threatens human food safety. Arbuscular mycorrhizal fungi (AMF) can form beneficial symbiosis with plant roots and improve plant resistance to toxic metalloids. Populus tomentosa, a fast-growing poplar species, shows great potential for As phytoremediation. However, it is still unclear how AMF mediate As stress resistance in this tree species. In this study, a pot experiment was conducted with or without Rhizophagus irregularis inoculation under non-As or As stress conditions. AMF colonization status, plant-growth performance, and root morphological traits were determined, and transcriptome sequencing was conducted. As stress limited AMF colonization and damaged P. tomentosa seedling performance, while R. irregularis inoculation improved biomass and root development to relieve As toxicity. Transcriptome sequencing revealed that many differentially expressed genes were induced by R. irregularis inoculation and As stress. Pathways related to signal transduction of jasmonate (JA) biosynthesis and metabolism were strongly activated by R. irregularis inoculation under As stress. Key transcription factor hubs such as GATA5 and WRKY57 linked mycorrhizal signals to JA-related gene expression in P. tomentosa seedlings under As stress. Our results revealed that AMF regulated JA-dependent transcriptional networks to enhance As tolerance in P. tomentosa seedlings, supporting the application of AMF-assisted poplar phytoremediation for soil remediation.