javascript:void(0) Hybridization is a potent mechanism for generating genetic diversity and transferring adaptive genetic loci across species or populations (lineages), enabling organisms to explore broader ecological niches. However, the effects of hybridization between species/lineages with different ploidy levels remain underexplored. In this study, we used transcriptomic approaches to investigate the abiotic stress tolerance of common reed (Phragmites australis) and in relation to polyploidy and hybridization. Our findings revealed that a brackish water population of a tetraploid lineage acquired salinity tolerance through adaptive introgression from an octoploid lineage. Among 46 adaptive genes with high FST values between populations, nine were significantly enriched in response to salicylic acid. In a common garden experiment, we chose two hybrid genotypes with similar genetic backgrounds to assess the consistency of adaptability from introgression under varying cadmium (Cd) concentrations. The Heze genotype exhibited a significant decline in net photosynthesis rate and chlorophyll content with increasing Cd concentrations, whereas the Panjin genotype exhibited greater tolerance. Correspondingly, the Heze genotype also had a higher number of differentially expressed genes under both low and high Cd concentrations. These findings suggest that introgressed loci may have varying functions in hybrid populations. This study enhances our understanding of how hybridization between lineages of different ploidy levels can lead to improved stress tolerance and its role in adaptive evolution.

Phragmites australis is the dominant species in the Yellow River Delta and plays an important role in wetland ecosystems. Ecological responses of the P. australis community to soil properties were investigated in 96 areas along the coastal-inland regions in the Yellow River Delta of China. The aim was to evaluate the relationship between phenotypic variation and environmental factors, reveal which functional traits could well respond to changes in electrical conductivity and soil water content, and the ecological strategies of P. australis. Within the range of soil water content (9.39–36.92%) and electrical conductivity (0.14–13.29 ms/cm), the results showed that the effects of soil water content and salinity were not equally important for the characterization of the morphological and physiological variability, and that plant functional traits including leaf traits and stem traits responded more strongly to soil salinity than soil water content. Our results suggested that salinity leads to reduced average height, specific leaf area, leaf area, and base stem diameter, but increased leaf water content and leaf thickness. The relationships between functional traits and electrical conductivity were generally linear and logarithmic. The coefficients of variation of morphological traits showed more phenotypic plasticity than the physiological traits. Salinity also led to the stress tolerator/competitor-stress tolerator (S/CS) strategies of P. australis; with the decrease of environmental stress, the main strategy gradually moved to the competitor (C) strategy, making P. australis the dominant species in the Yellow River Delta. KEYWORDS: Soil water content, Electrical conductivity, Functional traits, Plasticity, Life strategies.