| Arbuscular mycorrhizal(AM)fungi were widely distributed in various habitats including saline-alkali soils.The existence of AM fungi improved the structure and soil fertility of salinealkali soils.At the same time,the growth,development and diversity of AM fungi were also affected by soil factors,plant species and other factors.The unique composition of AM fungal community usually existed in saline-alkali land,which was different in the rhizosphere of the different plant or the same plants in different environments.The functions of AM fungi on plants were also different due to the various hosts.Under saline-alkali stress,AM fungi established mycorrhizal symbionts with plant roots,which had a certain impact on the growth,development and stress resistance of the host plants.Ajuga multiflora Bunge,a wild flower with high ornamental value,naturally distributed in the songnen saline grassland,and had been found to have a certain antioxidant capacity.A.reptans L.was a perennial herb belonging to the same genus as A.multiflora with strong adaptability.Compared with A.multiflora,the colored-leaf cultivar(A.reptans ‘Persian Pearl’)was of higher ornamental value and more widely used,making it an excellent ground cover plant.No reports had been reported on the symbiosis between A.multiflora,A.reptans and AM fungi.This study carried out an investigation on the diversity of AM fungi in the rhizosphere of A.multiflora in Songnen saline-alkali grassland,and the AM fungal community was inoculated to the root of A.reptans to deeply explored the functions of natural AM fungi in enhancing the ability of plants to tolerate salt and alkali from the aspects of growth,physiology and biochemistry of A.reptans by using pot experiment and simulating saline-alkali stress.The purpose of the study was to further understand the AM fungal resources in saline-alkali soil,to provide a certain theoretical rationale for further popularizing the application of AM fungi-Ajuga plants in saline-alkali soils restoration,and then provide new ideas and ways for improving saline-alkali agricultural land by mycorrhizal technology.The main results of this research were as follows:(1)The root systems of A.multiflora at 6 sampling sites in Songnen saline-alkali grassland were colonized by AM fungi to form Arum arbuscular mycorrhiza,and the colonization rate reached 100%.The colonization intensity,arbuscule abundance and vesicle abundance showed different degrees of differences in different samples.(2)A total of 38 species of AM fungi belonging to 11 genera in the rhizosphere soil of A.multiflora were identified by morphological methods.There were 11 AM fungal species of Glomus which was the genus with the highest species abundance,and 7 AM fungal species of Acaulospora,4 AM fungal species of Claroidoglomus,Rhizophagus,as well as Septoglomus,2AM fungal species of Funneliformis,and Sclerocystis,as well as 1 species of Ambispora,Pacispora,Paraglomus and Scutellospora respectively.At the same time,with the use of highthroughput sequencing technology,100 virtual species of AM fungi belonging to 5 genera with clear species information were identified,of which the most species were Glomus,with a total of 81 species.In addition,there were 8 species of Glomus,5 species of Diversipora,4 species of Claroidoglomus,1 species of Ambispora and Archaeospora.(3)By analyzing the dominance of species and genera identified by morphology,the dominant genera(Important value>50%)of AM fungi obtained in the rhizosphere of Ajuga multiflora were Acaulospora,Glomus,Rhizophagus,Sclerocystis,Septoglomus.The dominant species(Important value>50%)were Se.deserticola,A.delicata,G.reticulatum,G.melanosporum,G.pansihalos,S.sinuosa and Se.constrictum.The results of high-throughput sequencing showed that the virtual species of Glomus species VTX00130 had the highest relative abundance and were distributed in all sampling sites.(4)By analyzing the effects of soil factors such as soil p H,EC,the contents of soil organic matter,total nitrogen and total phosphorus on AM fungi,it was found that soil p H,salt content and total nitrogen were negatively correlated with the colonization level of AM fungi and positively correlated with spore density(P<0.05);Soil organic matter content and total nitrogen content had a positive correlation with spore density,but had little relationship with species richness of AM fungal community(P<0.05);Soil total phosphorus content was negatively correlated with spore density and species richness,but not with the colonization ability of AM fungi(P<0.05).(5)Through the inoculation test of AM fungi,a strong symbiotic ability between AM fungal community in the rhizosphere of A.multiflora and A.reptans was verified.AM fungi and A.reptans also formed Arum arbuscular mycorrhiza.(6)Although the colonization ability of AM fungi was affected by saline-alkali stress,it still effectively promoted the growth and development of A.reptans.Firstly,the growth of roots was improved by increasing the total root length,root surface area,root volume and root branch number;Secondly,it promoted the absorption of water,phosphorus,promoted plant photosynthesis,thus accumulating the biomass of A.reptans;Then,by accumulating more osmoregulation substances such as soluble protein and soluble sugar,the osmoregulation ability of A.reptans was improved and the osmotic stress was alleviated;Finally,by increasing the activity of SOD and the content of GSH,the antioxidant capacity of A.reptans was improved,oxidative damage was reduced and the MDA content in plants was also reduced,so as to AM fungi improved saline-alkali tolerance and the growth of A.reptans. |
PDF Full Text Request