Non-host Plant Species: Definition, Description, and Mechanisms of Interaction with Arbuscular Mycorrhizal Fungi

About 18–29% of vascular plant species, e.g., important crops, are not involved in a symbiotic interaction with arbuscular mycorrhizal fungi (AMF). These species are known as “non-host” plants. However, these plants can be colonized under certain conditions and develop rudimentary AM (RAM) phenotypes, which often results in a decrease in plant growth and an increase in resistance to pathogens and insects. Several “symbiosis toolbox” genes that are present in the genome of host plants are conserved in non-host plants. Moreover, specific non-symbiotic genes can be brought into play for symbiosis in non-host plants. Altogether, the results show that molecular connections with the symbiosis machinery have still remained in non-host plants, which can enhance the prospect of engineering this functional trait for agricultural plants.