A molecular study of Italian ryegrass grown on Martian regolith simulant

In the last decade, the exploration of deep space has become the objective of the national space programs of many countries. The International Space Exploration Coordination Group has set a roadmap whose long-range strategy en-visions the expansion of human presence in the solar system to progress with exploration and knowledge and to accel-erate innovation. Crewed missions to Mars could be envisaged by 2040. In this scenario, finding ways to use the local resources for the provision of food, construction materials, propellants, pharmaceuticals is needed. Plants are impor-tant resources for deep space manned missions because they produce phytochemicals of pharmaceutical relevance, are sources of food and provide oxygen which is crucial in bioregenerative life support systems. Growth analysis and plant biomass yield have been previously evaluated on Martian regolith simulants; however, molecular ap-proaches employing gene expression analysis and proteomics are still missing. The present work aims at filling this gap by providing molecular data on a representative member of the Poaceae, Lolium multiflorum Lam., grown on pot-ting soil and a Martian regolith simulant (MMS-1). The molecular data were complemented with optical microscopy of root/leaf tissues and physico-chemical analyses. The results show that the plants grew for 2 weeks on regolith simulants. The leaves were bent downwards and chlorotic, the roots developed a lacunar aerenchyma and small brownish deposits containing Fe were observed. Gene expression analysis and proteomics revealed changes in tran-scripts related to the phenylpropanoid pathway, stress response, primary metabolism and proteins involved in trans-lation and DNA methylation. Additionally, the growth of plants slightly but significantly modified the pH of the regolith simulants. The results here presented constitute a useful resource to get a comprehensive understanding of the major factors impacting the growth of plants on MMS-1.