Diversity Of Arbuscular Mycorrhizal Fungi In Root Systems And Inter-root Soils Of Wine Grapes At The Eastern Of The Helan Mountains And Their Correlation With Soil Factors

The wine grape region at the east of the Helan Mountains in Ningxia has been recognized by experts from both domestic and foreign as one of the best ecological zones for grape growth due to its advantaged geographical conditions.However,the clear-cut long-term cultivation of vineyards has led to poor soil and a decrease of microbial diversity,which have resulted in poor plant growth,reduced resistance to adversity and lower fruit quality.Arbuscular mycorrhizal fungi(AMF)establish symbiotic relationship with most higher plants,colonize plant roots,and form hyphae,vesicles,hyphae rings and other structures.Numerous studies have shown that AMF can promote water transport and nutrient uptake in plants,improve the resistance of host plants to biotic and abiotic stresses,promote plant growth and improve plant yield and quality.However,studies on AMF in the root system of wine grapes in the eastern Helan Mountains have not yet been reported.In this study,we collected root samples and inter-root soil samples from different varieties of wine grapes in different ecological zones and different growth periods in the eastern Helan Mountains,and used high-throughput sequencing technology to comprehensively analyse the composition and diversity of inter-root AMF communities in wine grapes,in order to provide a reference for making full use of AMF resources in wine grapes.The AMF colonisation status of the root system of wine grapes in different ecological zones and its correlation with soil factors were investigated,and the effect of AMF colonisation on soil nutrient transformation and utilisation was explored.The main findings were as follows,1.Illumina MiSeq high-throughput sequencing technology was used to analyze the structural characteristics of the inter-root AMF communities of ’Cabernet Sauvignon’(CXZ),’Merlot’(ML)and’Chardonnay’(XDL)grapes at Yuanshi Chateau.The results showed that all three varieties of wine grapes can be colonized by AMF,of which Glomus is the dominant genus.187 OTUs were obtained in the three varieties of wine grapes,attributed to 20 AMF species in four genera,with the highest relative abundance of Glomus,accounting for 99.21%of AMF.a-diversity analysis showed that the ML samples Shannon index was significantly higher than CXZ,while ML and XDL were not significantly different;the Simpsoneven index of ML and XDL were all significantly higher than CXZ;Non-significant differences in sobs index between wine grape varieties;PCoA analysis showed that wine grape varieties changed the inter-root AMF community structure;AMF Lefse multi-level species difference analysis showed that Glomus-MO-G17-VTX00114 and unclassified_g__Glomus_f__Glomeraceae are the iconic taxa of CXZ;Glomus-perpusillum-VTX00287 is the iconic taxon of ML;Glomus-sp_-VTX00304 and Glomus-viscosum-VTX00063 are iconic taxa of XDL.2.Illumina MiSeq high-throughput sequencing technology was used to examine the differences in AMF diversity and community composition of inter-root soils of wine grapes in the eastern foothills of Helan Mountains,and to analyze the effects of soil factors on AMF community diversity.The results showed that:(1)The OTUs detected in the inter-root soil of wine grapes at different periods and sample sites were 93 and 187,attributed to three genera 11 species and five genera 30 species,respectively.Glomus is a dominant genus in wine grapes at different growth periods and in different locations.(2)The Shannon and Simpsoneven index of AMF diversity were significantly higher in July than in May and September,while the Sobs index were not significantly different between the periods(P<0.05).The Sobs,Shannon and Simpsoneven indices showed some variability among the different sites,all showing significantly higher(P<0.05)in the LL sample than in the other samples.(3)Correlation analysis showed that total N,pH and soil peroxidase were significantly and positively correlated with Sobs index and Shannon index(P<0.05),while pH and Simpsoneven index were significantly and positively correlated(P<0.05).Of these,peroxidase has the greatest impact on AMF diversity.3.To further investigate the colonization of AMF in the root system of wine grapes at the eastern foot of the Helan Mountains in Ningxia,root and soil samples were collected from vineyards of HD,GL,ZH,LL,XXW,XG and FHD.The root and soil samples of ’Cabernet Sauvignon’ were collected at three soil levels:0～20 cm,20～40 cm and 40～60 cm,to study the colonisation of AMF and its correlation with soil factors.The results showed that the root system of wine grapes was colonised by AMF and formed hypha,vesicle circles and hypha rings in all seven sites.Spatial heterogeneity in AMF colonization rates and spore densities was evident in the seven sample sites.The highest total AMF colonization rate and spore density were found in the ZH,with 70.04%and 252 spores/50g of soil,respectively,while the lowest average colonisation rate was found in the HD sample,at 6.28%.The XXW sample site had the lowest mean spore density of 63 spores/50g of soil.The maximum values of total AMF colonization rate and spore density in the seven sample sites were mainly concentrated in the 0～40 cm soil layer,and there was some variability among different soil layers.Principal component analysis showed that alkaline nitrogen,sucrase,urease,alkaline phosphatase,catalase and total nitrogen combined to reflect the inter-root soil nutrient status of wine grapes in the seven winery sample sites at the eastern foot of the Helan Mountains.AMF colonisation is influenced by soil factors.Soil factor correlation analysis showed that AMF spore density was highly significantly and positively correlated(P<0.05)with organic matter,alkaline dissolved nitrogen,sucrase,alkaline phosphatase and urease.AMF total colonisation rate,colonisation intensity,mycelial colonisation rate and vesicle colonisation rate were highly significantly positively correlated with fast-acting phosphorus,pH and catalase activity(P<0.05).It shows that AMF can form a good symbiosis with wine grape roots and that the ecological distribution of AMF is closely related to soil factors.4.To clarify the effect of grass cultivation on AMF enrichment in the inter-root soil of wine grapes.The effect of in-row grassing on AMF colonisation rate and spore density in grape roots in ZH and XG was studied using ’Cabernet Sauvignon’ roots and inter-root soil,and the correlation between AMF colonisation and soil factors was analysed.Compared to clear-cut cultivation,the AMF colonisation rate and spore density of endophytic tall fescue in ZH,increased by 15.36%and 40.06%respectively.The AMF colonisation rate and spore density of endophytic amaranth AMF in the rows of XG increased by 28.66%and 135.56%respectively.Tall fescue was significantly more enriched in AMF spores than Amaranthus(P<0.05).Significantly higher soil nutrient content under the sod-culture.Redundancy analysis showed that spore density,colonization rate,mycelial colonization rate and colonization intensity were positively correlated with fast-acting phosphorus and alkaline phosphatase,respectively,and highly significantly negatively correlated with pH.It shows that the artificial grass is more conducive to the establishment of a symbiotic relationship between beneficial microorganisms and the grape root system,promoting the transformation of soil nutrients for the uptake by the grape root system.