| Because of its drought tolerance and rapid growth,it which is Populus cathayana Rehd.has become a pioneer tree for wind prevention and sand fixation and commercial tree species.However,the incidence of poplar canker disease is increasing with the increasing expansion of poplar plantation area and the single cultivation and management mode,which seriously restricts the development of forestry.In order to explore the effect of arbuscular mycorrhizal fungi on improving the resistance of poplar to canker disease,this study took poplar as the experimental material,inoculated with Rhizophagus irregularis and then inoculated with Dothiorella gregaria.To study the effect of arbuscular mycorrhizal fungi(AMF)on the resistance of poplar to canker disease,the main results are as follows:1.The inoculation of AMF promoted the growth of poplar and the content of permeable substances.The biomass of poplar inoculated with AMF was significantly increased.Under healthy conditions,the fresh weight of leaves and roots of poplar inoculated with AMF,increased by 68.69% and 30.45%,respectively.Under the stress of pathogenic bacteria,the weight of leaves and stems increased by 35.26% and 43.95%.The incidence of canker disease was significantly reduced from 73.81% to 61.56%,and the disease index was reduced by30.15%.The total root area,surface area and root length of infected poplars increased by23.21%,21.28% and 30.29% after inoculation with AMF.Inoculating AMF significantly increased the Mg and P content of poplar in root,and the content of Mg was significantly increased by 185.11%,and the content of P was increased by 52.20% under disease stress.The contents of chlorophyll and cellulose increased by 65.08% when AMF was inoculated simultaneously.The results showed that the inoculation of poplar could change the root morphology,increase the absorption area to improve the ability of the plant to absorb nutrients,promote the growth of poplar,and improve its own defense function.The accumulation of malondialdehyde in roots and stems of infected poplars was significantly decreased by 31.88%and 47.81% with AMF inoculation.After inoculation with AMF,the content of proline increased by 545.74%,in roots by 241.86%,and soluble protein increased by 77.19% and175.44% respectively in leaves and stems.These results indicated that AMF could improve the antioxidant capacity of poplar,induce the production of proline and other secondary metabolites,and improve the disease resistance.2.AMF inoculation increased the activity of antioxidant enzymes and pathogen-related proteins of poplar and enhanced the disease resistance.AMF inoculation could increase PPO activity,SOD activity in roots and CAT activity in leaves.PPO activity increased by 210.65% in leaves,113.78% in roots and 205.20% in stems,respectively.SOD activity in roots and CAT activity in leaves increased by 69.72% and54.95%,respectively.Inoculation of AMF could also increase the activity of pathogen-related proteins in poplar.The activity of chitinase in roots of poplar inoculated with AMF decreased,but the activity of β-1,3-glucanase,polygalacturonase and pectin methyl esterase increased after inoculating with AMF,and the activity of β-1,3-glucanase in roots increased by 35.50%.The polygalacturonase activity was increased by 40.08%,and the activity of pectin methyl esterase in stem was increased by 30.43%.Among them,the polygalacturonase activity in the stem of infected poplar was significantly increased by 106.35% after inoculation with AMF,indicating that AMF could improve the activities of disease-related antioxidant enzymes and disease-course related proteins in poplar,inhibit the growth of pathogenic bacteria and reduce the incidence of canker disease.Therefore,AMF could promote the growth of plants,increase the content of osmotic substances and reduce the incidence of canker disease.AMF could also improve the antioxidant capacity of poplar,improve the activity of path-related proteins and enhance the disease resistance of poplar. |
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