Improving crop plant productivity in the current scenario of global climate change is among the major challenges for an evergrowing human population.In this respect,there is great interest in root symbioses such as arbuscular mycorrhizas (AMs) and nitrogen-fixing symbioses (NFSs),with their ability to feed plants with microbe-derived inorganic nutrients and extend plant tolerance to drought,salt stress,and pathogenic attacks (Harman and Uphoff,2019).