Colonization Characteristics and Diversity of Arbuscular Mycorrhizal Fungi in the Rhizosphere of Iris lactea in Songnen Saline-alkaline Grassland

To understand arbuscular mycorrhizal(AM)fungi resources and develop AM fungal species in ornamental plants with saline-alkaline tolerances,Iris lactea,which grows in the Songnen saline-alkaline grassland with a high ornamental value,was selected as the experimental material,and the colonization characteristics of its roots and the AM fungal diversity in its rhizosphere were explored.The results of the observations and calculations of mycorrhizae from ten different samples showed that AM fungi colonized the roots of I.lactea and formed Arum-type mycorrhizal structures.There was a significant correlation between soil spore density and pH value,while the colonization rate showed a fluctuating trend with increasing pH values.The observed colonization intensities were of Levels II(1%–10%)or III(11%–50%),and the vesicle abundances were of grades A2 or A3 among different sites.AM fungi produced a large number of mycelia and vesicles in the roots of I.lactea after colonization.Thirty-seven species belonging to 15 genera of AM fungi were isolated from the rhizosphere of I.lactea and identified by morphological identification.Funneliformis and Glomus were the dominant genera,accounting for 21.79%and 20.85%of the total number,respectively.F.mosseae and Rhizophagus intraradices were isolated in all samples with importance values of 58.62 and 51.19,respectively.These results are expected to provide a theoretical basis for the analysis of the salt tolerance mechanism of I.lactea and for the discovery,exploration and further screening of AM fungal resources with salinity tolerances in saline-alkaline soils.

Arbuscular Mycorrhizal Fungal Colonization at Different Succession Stages in Songnen Saline-Alkali Grassland

Arbuscular mycorrhizal(AM)fungi can form symbiosis with 90%of the vascular plants and play important roles in ecosystem.To realize the AM fungal colonization at different succession stages in saline-alkali land and screen AM fungi species with great functions,roots and soil samples were collected from the three succession stages of Songnen saline-alkali grassland.The soil properties and AM fungal colonization were measured,and the fungus distributed extensively in three stages was annotated by sequencing for AML1/AML2 target,subsequently,maize was selected as the host to verify its colonization.The results showed that the soil properties improved with the succession of saline-alkali grassland.The plants’communities of the three stages could be colonized by AM fungi,and the colonization rate of Leymus chinensis(the third stage)ranged from 66.67%to 100%,Puccinellia tenuiflora(the second stage)ranged from 50%to 80%,while the Suaeda glauca(the first stage)was only 35%–60%.Glomeraceae sp1 was identified as the dominant AM fungi species which occurred frequently in the succession of saline-alkali land with the isolation frequency,relative abundance,and importance value of 100%,18.1%,and 59.1%,respectively.The colonization rate of Glomeraceae sp1 in maize ranged from 80%to 87%and similar mycorrhizal characteristics were detected in the roots of P.tenuiflora,S.glauca,and L.chinensis,indicating that Glomeraceae sp1 colonized the samples in the field.The correlation matrix indicated that colonization rate,colonization intensity,and vesicle abundance were closely related to soil conditions most,and they were related significantly to all the soil properties except cellulase activity.Besides,redundancy analysis(RDA)showed that soil properties drove the changes of AM fungal colonization and sporulation.These results will provide theoretical support for realizing the relationship between AM fungal colonization and soil conditions,and also for the exploration of AM fungi species with great functions.

Claroideoglomus etunicatum improved the growth and saline-alkaline tolerance of Potentilla anserina by altering physiological and biochemical properties

To investigate the effects of arbuscular mycorrhizal(AM)fungi on the growth and saline–alkaline tolerance of Potentilla anserina L.,the seedlings were inoculated with Claroideoglomus etunicatum(W.N.Becker&Gerd.)C.Walker&A.Schüßler in pot cultivation.After 90 days of culture,saline–alkaline stress was induced with NaCl and NaHCO_(3)solution according to the main salt components in saline–alkaline soils.Based on the physiological response of P.anserina to the stress in the preliminary experiment,the solution concentrations of 0 mmol/L,75 mmol/L,150 mmol/L,225 mmol/L and 300 mmol/L were treated with stress for 10 days,respectively.The mycorrhizal colonization rate,mycorrhizal dependence,chlorophyll content,malondialdehyde content,antioxidant enzyme activities,osmoregulation substances content and water status were measured.The results showed that with the increase of NaCl and NaHCO_(3)stress concentration,mycorrhizal colonization rate,colonization intensity,arbuscular abundance and vesicle abundance decreased,and reached the lowest value at 300 mmol/L.Strong mycorrhizal dependence was observed after the symbiosis with AM fungus,and the dependence was higher under NaHCO_(3)treatment.Under NaCl and NaHCO_(3)stress,inoculation with AM fungus could increase chlorophyll content,decrease malondialdehyde content,increase activities of superoxide dismutase,peroxidase and catalase,increase contents of proline,soluble sugar and soluble protein,increase tissue relative water content and decrease water saturation deficit.It was concluded that salt–alkali stress inhibited the colonization of AM fungus,but the mycorrhiza still played a positive role in maintaining the normal growth of plants under salt–alkali stress.