Transgenerational effects of elevated CO 2 : Downregulation of photosynthetic efficiency and stomatal sensitivity to drought

Increasing atmospheric CO 2 and drought are major symptoms of anthropogenic climate change with profound effects on plant growth. Transgenerational memory (i.e. influence of the parental environment on offspring phenotype and performance) has been suggested as a relevant mechanism for plants to build-up adaptative capacity for rapid environmental changes. However, this mechanism of pre-adaptation remains poorly investigated so far. We investigated intra- and transgenerational effects of elevated CO 2 on drought response of wheat. We used seeds from a FACE (Free Air Carbon Dioxide Enrichment) experiment with ambient and elevated CO 2 to grow plants in climate chambers in which we varied CO 2 , atmospheric water demand and soil moisture. We quantified photosynthetic efficiency, stomatal sensitivity and biomass production. We observed intragenerational upregulation of photosynthetic efficiency but transgenerational downregulation of photosynthetic efficiency, stomatal sensitivity and water use efficiency as response to maternally elevated CO 2 . Plant biomass was affected by drought and experimental CO 2 but not by maternal CO 2 . Our study showcases the importance of transgenerational memory effects when studying climate change response of plants and could have major implications for our understanding of global dynamics of carbon sequestration. It highlights the pressing need for multi-generational experiments accounting for transgenerational memory effects of elevated CO 2 .