Arbuscular mycorrhizal fungi-mediated drought stress tolerance in kenaf (hibiscus cannabinus l.): a mechanistic approach

Drought is one of the important factors limiting crop growth. Plants can enhance resistance to various stressors by forming symbiotic relationships with arbuscular mycorrhizal fungi (AMF). However, the regulatory mechanism of AMF on the drought tolerance of kenaf remains unclear. Therefore, we studied the effects of inoculating Claroideoglomus etunicatum (C. etunicatum, Ce) on the growth, gaseous exchange, antioxidant enzymes activity, osmotic regulatory substances, endogenous hormones, elemental content, and drought resistance related gene expression in kenaf under different water conditions, as well as the changes in soil enzymes after inoculation with Claroideoglomus etunicatum (Ce). The results showed that the biomass of kenaf inoculated with AMF significantly increased under drought conditions; For the aboveground parts of kenaf, inoculation with AMF improved the gas exchange parameters, and synthesized more osmotic regulatory substances to resist drought stress. At the same time, AMF also enhanced the scavenging ability of reactive oxygen species and reducing the cell damage caused by ROS; For the root of kenaf, AMF promoted the root development, enhanced the ability of plant element and water absorption, and significantly increased the content of IAA and ABA in the roots of kenaf under drought stress, reaching 26.45% and 6.69%, respectively. The content of globulin-related soil proteins (GRSP) were increased after inoculation with AMF, and the soil enzymes activity was improved, making the soil easier to maintain water, for the growth of kenaf; Furthermore AMF regulate the expression of aquaporin related genes (HcPIP1;2, HcPIP2;7) and improved the tolerance of kenaf to drought. Our study is not limited to the direct effects of AMF on plants, but also indirectly affects plants by analyzing the effects of AMF on the physicochemical properties of soil in plant roots. These results indicate that AMF played an important role to promote the growth of kenaf under drought conditions.