Research On Diversity And Function Of Arbuscular Mycorrhizal Fungi From Taraxacum Mongolicum Rhizosphere In Songnen Saline-alkali Grassland

Arbuscular mycorrhizal fungi(AMF)are the most important type of endophytic fungi,and can form a symbiotic relationship with the roots of more than 80%of higher terrestrial plants in nature.AM symbiosis plays an important role in improving the growth of host plants and enhancing the tolerance of plants to various stresses.In addition,AMF was currently used in horticultural crops.In this experiment,the roots of Taraxacum mongolicum and its rhizosphere soil collected from Songnen saline-alkali grassland were used as materials to study the infection characteristics of AM fungi.The diversity of AM fungi was analyzed by morphological identification and molecular biological identification,which also used to determine the dominant AM fungal species in presence of dandelion roots.In addition,pot experiments were conducted to investigate the effects of inoculation dominated Glomus mosseae on dandelion seedlings regarding growth,nutrient absorption,tissue water content,chlorophyll content,antioxidant enzymes and physiological metabolism characteristics.Moreover,the relevant mechanism for salt tolerance of dandelion was explored.The key research findings as below:1.The soil pH values of rhizosphere soil collected from dandelion in Songnen saline-alkaline grassland reached from 7.34 to 8.63.Under different pH habitats,dandelion roots were also infected by AM fungi and formed a typical paris-type mycorrhizal structure.However,there were significant differences in colonization characteristics at different soil pH values,with a vesicle abundance of 33%at pH 7.66,a vesicle abundance of 36.8%and 27.3%at pH 7.80,and a clump abundance of 1.9%and 2.85%,respectively.When the pH is 7.52,the vesicle abundance reaches a maximum of 39.35%,the abundance abundance reaches a maximum of 19.7%at pH 7.76.and at the pH of 7.80,7.76 and 7.66,the infection intensity reaches the highest 92.5%.2.In the 10 soil samples of dandelion roots collected in this experiment,21 genera and 6 species were identified by morphological analysis,among which 10 species were Glomus,accounting for 47.6%of the total species.Glomus mosseae is the dominant species of dandelion roots,possessing 80%importance values.5 species of Acaulospora,3 species of Scutellospora,and genus Pacispora,Archaeospor,and Gigaspora each one also included.On this basis,Nested-PCR was used to further identify the dominant species of Glomus mosseae,which was initially identified by morphological identification.The sequence number of MH660533 was obtained in NCBI,and the results were identical with the morphological identification.The accuracy of morphological identification was further verified.3.Pot experiments showed that dandelion(60d in growing period)formed a stable symbiotic relationship with the dominant strain,Glomus mosseae.Salt stress solutions with five concentration gradients of 0,100,200,300,and 400 mM were used to conduct a 10 d stress test on dandelion grown for 60 days.The results showed that the dandelion inoculated with AMF increased the biomass as well as plant height and the mycorrhizal dependence reached 48.33%in 400 mM concentration of NaCl.Mycorrhiza-inoculated improved the ability of dandelion to absorb water under salt stress and increased the chlorophyll content in dandelion,with SOD,POD,CAT activity and soluble protein content increased to different degrees while mycorrhizal treatment reduced MDA,proline and relative conductivity in dandelion.4.Under salt stress,the content of Na+was increased compared with no salt treatment whether inoculation AMF or not.In addition,the excessive accumulation of Na+in the Taraxacum mongolicum resulted in a decrease in the content of P,Fe and Zn elements.Glomus mosseae increased the elements content of P,Mg,Cu,and Zn in dandelion while reducing the absorption of Na+.Overall,arbuscular mycorrhiza can increase the uptake of nutrients by dandelion under salt stress and reduce the absorption of Na+to promote the ion balance in dandelion.In this experiment,the diversity of AM fungi around the roots of Taraxacum mongolicum in Songnen saline-alkali grassland was investigated in order to obtain a Saline-Alkali-Tolerant strain of AM fungi,and the response of AMF-Taraxacum mongolicum symbiotic system to salt stress was studied.The aim of this stuay was to provide a new approach and idea for improving and restoring saline-alkali agricultural land with mycorrhizal technology,and to provide a reference to popularize the application of Taraxacum Mongolic in remediating salt lands.