Effects of arbuscular mycorrhizal fungi on maize growth and drought tolerance under drought stress
[Objective]The present study aimed to understand the effects and mechanism of Arbuscular Mycorrhizal Fungi(AMF)on maize growth and drought tolerance under drought stress.[Method]A maize hybrid widely planted in Yunnan province was used as materials,which was planted in pots and treated with AMF inoculation and non-inoculation controls,respectively,under different water stress conditions,then the soil physicochemical properties,mycorrhizal colonization rate,plant phenotype,rhizosphere soil bacterial community of different treatments were collected and analyzed.[Result]AMF could infect maize roots well and form symbionts,but the mycorrhizal colonization rate decreased with the increase of drought severity;Inoculating AMF could increase the pH value of maize rhizosphere soil,and thus reduced soil acidity.In-oculating AMF could promote the growth of maize plants,but did not affect the growth cycle of plants;Compared with non-inoculation control,the relative water content of maize leaf increased,the osmotic regulating substances reduced to varying degrees,and the activity of antioxidant enzyme under moderate drought increased significantly for AMF inoculation,so the damage of drought to plants was alleviated.AMF inocula-tion resulted in a change in the number of bacteria OTUs in the rhizosphere soil,and the number of significantly enriched OTUs increased with the increase of drought severity.AMF inoculation under drought stress could increase the diversity of bacterial communities,alter the structure of bacterial communities,and enrich the metabolic function of rhizosphere soil bacterial communities.There were significant correla-tions between the abundance of bacterial community in maize rhizosphere soil and mycorrhizal colonization rate,soil pH,plant height and dry weight.The mycorrhizal colonization rate was positively correlated with soil pH,plant growth indicators,chlorophyll content,relative water content of leaves,antioxidant enzyme activity,while negatively correlated with soluble sugar content,malondialdehyde content and proline con-tent.Among the dominant bacteria in rhizosphere soil,Cyanobacteria,Bacteroidetes,Actinobacteria,and Firmicutes had a certain degree of correlation with plant growth and drought tolerance.[Conclusion]Inoculating AMF can reduce soil acidity,promote maize growth and enhance its drought tolerance.At the same time,it can increase the diversity of maize rhizosphere soil bacterial communities,change the structure and function of rhizosphere bacterial communities,which will provide reference for further utilizing AMF to improve maize's response to drought stress.
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