Arbuscular mycorrhizal fungi alleviate root damage stress induced by simulated coal mining subsidence ground fissures

Coal mining results in surface subsidence and induces the development of ground fissures that damage surrounding plant roots. Very few studies have explored the stress of root damage caused by ground fissures and whether arbuscular mycorrhizal fungi (AMF) can relieve root damage stress induced by ground fissures. In the present study we simulated ground fissure induced root damage, examined the resultant changes in endogenous hormones, root system morphology, leaf area, leaf chlorophyll content, nutrient content and biomass of maize, and examined the ameliorative effects of AMF on maize with root damage. Ground fissures led to significantly higher levels of endogenous abscisic acid (ABA) but significantly reduced levels of indole-3-acetic acid (IAA), gibberellins (GA) and cytokinin (CTK). In addition, ground fissures led to significantly reduced root biomass, total root length, root tip number, total root volume, plant nutrient content, leaf chlorophyll content and leaf area. The shoot biomass of root damaged maize decreased significantly by 46%. By contrast, AMF increased IAA and CTK levels in maize roots, reduced ABA levels, improved the hormone balance of damaged plants, increased total root length, root tip number, total root volume, leaf area and leaf chlorophyll content, increased nutrient content and increased shoot biomass by 34%. Overall, by simulating coal mining subsidence ground fissures, the study investigated the effects of root damage stress on plant biomass, found that AMF can alleviate the mechanical damages to the root system, and provided a theoretical basis for microbial remediation in areas subject to subsidence due to coal mining.