eLife Assessment
This important study demonstrates that nutrient resorption efficiency in the widespread wetland grass Phragmites australis is largely canalized by phylogeographic lineage, ecotype and geographic origin, rather than responding plastically to short-term salt stress. The findings have implications beyond plant ecophysiology because they suggest that predictions of wetland nutrient cycling under increasing salinization should account for the genetic composition of plant populations. The evidence supporting the central conclusions is compelling, based on a well-designed common-garden experiment involving 110 genotypes, paired control and salinity treatments, and convergent metabolomic, ionomic and whole-plant evidence confirming that the treatment imposed substantial physiological stress. The interpretation is nevertheless limited to one growing season and a single, moderate salinity treatment, leaving open whether chronic, more severe or multigenerational exposure might induce plastic or transgenerational responses; further clarification of the relationships among phylogeographic lineage, ecotype and latitude, and a more cautious interpretation of the variance explained by latitude, would strengthen the manuscript.