High CO2 induction of pathogenesis-related responses in plants: signaling, metabolic pathways, and agronomic impact – HIPATH

Despite food security concerns linked to effects of climate change, knowledge of how increased CO2 impacts plant-pathogen interactions remains extremely fragmentary. Based on our recent observations that growth of Arabidopsis and common bean at elevated CO2 is sufficient to induce biotic stress responses, the HIPATH project brings together six teams working at two French centers in Orsay and Clermont-Ferrand to identify how this effect impacts on plant productivity and pathogen resistance and to elucidate the underlying mechanisms. HIPATH will use reverse and forward genetics to identify genes involved in coupling high CO2 to induction of pathogenesis-related (PR) metabolism, establish whether specificity exists between monocotyledonous and dicotyledonous species in the effects of high CO2, define the impact of high CO2 on PR responses in a crop growing in the field, and identify genetic variation that can be exploited in breeding programs. The programme will be conducted on several plant species, with the aim of evaluating taxonomic specificities in responses to high CO2. The use of Arabidopsis will favour rapid progress, via genetic screens, while the impact of high CO2 on biotic stress will also be investigated in an agronomically important dicot (bean), as well a model and crop monocot (Brachypodium and wheat). The programme wll generate new insights into CO2 signalling, identify links between primary and secondary metabolic pathways, provide new information on salicylic acid synthesis pathways in plants, and assess the impact of CO2 on biotic stress responses in different genotypes of wheat growing in field conditions. Fundamental knowledge generated in these areas will be relevant to predicting plant performance in future climates and to efforts to optimize conditions for effective priming for improved resistance to biotic invaders.