Polymer amendment regulates cadmium migration in cadmium contaminated cotton field: Insights from genetic adaptation and phenotypic plasticity.

Polymer materials have been widely used in the remediation of soil heavy metal contamination for their good performance in the absorption of metal ions. To reveal the effect of polymer amendment (PA) on the remediation of cadmium-contaminated cotton fields, the cadmium (Cd) fractions in soil, Cd concentration in cotton organs, bioconcentration factor (BCF) of Cd, translocation factor (TF) of Cd, and the antioxidant capacity and photosynthesis of functional leaves were evaluated combining with the transcriptomic and metabolomic analyses, in barrel experiments in the field at the flowering and boll-forming stage of cotton. The results showed that, cotton improved the tolerance to Cd through self-regulation in Cd-contaminated soil. The expression of oxoglutaric acid and jasmonic acid were down-regulated by the application of PA to improve the photosynthetic rate (7.71%-46.20%), chlorophyll content (17.59%-63.18%), chlorophyll fluorescence (7.66%-32.25%), and antioxidant enzyme activity (15.49%-45.50%) of functional leaves, and the down-regulation of the expression of jasmonic acid and up-regulation of the expression of stearic acid reduced the exchangeable Cd concentration in the soil, which reduced the transport of Cd from the root to the bolls (54.39%). Thereby, the balance of the genetic adaptation and phenotypic plasticity of cotton was achieved, and the cell structure of leaves was restored. This study deepens our understanding of the molecular mechanism of PA in the remediation of Cd contamination in cotton fields, and provides guidance for the remediation of heavy metal contamination in farmland soil and agricultural safety under drip irrigation.