| Naked barley(Hordeum vulgare L.var.Nudum Hook.F.)was a specific forage and food crop of Qinghai-Tibet plateau in China.Naked barley had strong cold resistance and short-growth period characteristics,which was the only normal grain in the cold area where altitude was more than 4200 meters.However,the Naked barley was threatened by root rot diseases in recent years.Therefore,this study investigated the occurrence dynamics and took some samples of Naked barley root rot diseases in Qinghai-Tibet plateau of northwest China,such as Gannan Tibetan Autonomous Prefecture,Gansu province and Qinghai province.A series of research of Naked barley root rot diseases and influence to rhizosphere micro-ecology were done with pathogen and rhizosphere micro-ecology,and the following aspects are mainly included:(1)The investigation of the harm of root rot diseases on Naked barley seedling and adult plants was carried out in Qinghai-Tibet plateau of northwest of China from 2015 to 2016,respectively.Naked barley root rot diseases incidence was 5% to 20% in the field.Samples of 102 pieces seedling and 75 pieces adult plants of Naked barley root rot diseases were collected.(2)Naked barley root rot pathogens were separated by ordinary plate separation method.Pathogen purification was done by using single spore separation method.And pathogenicity was determined by a beaker of water-agar and potted plants methods.The 235 pathogen strains were isolated from Naked barley root rot disease samples verified by Koch's rule.There were 134 Fusarium avenaceum strains,26 Bipolaris sorokiniana strains,24 Fusarium equiseti strains.Fusarium avenaceum was advantage pathogen in each region.Followed by Fusarium equiseti or Bipolaris sorokiniana in the majority.There were different pathogens constitution found in different parts,such as Fusarium flocciferum and Fusarium langsethiae were characteristic pathogen in Gannan of Gansu province,however,in Haidong and Haibei,Qinghai province,Microdochium bolleyi and Nectria gliocaldioides were characteristic pathogens.(3)The types of Naked barley root rot disease had been identified as 4 kinds that were Naked barley Crown rot,Common root rot,Microdochium root rot and Nectria root rot,which based on the pathogen,symptoms,and previous studied of same kind of crops.The Naked barley Crown rot was distributed most widely,and its pathogens were Fusarium avenaceum,Fusarium equiseti,Fusarium acuminatum,Fusarium flocciferum and Fusarium langsethiae.The Common root rot pathogen was Bipolaris sorokiniana.In addition,The Microdochium root rot and Nectria root rot were widely distributed in Qinghai province and pathogen was Microdochium bolleyi and Nectria gliocaldioides,respectively.(4)The strains of pathogen had different pathogenicity between same species by studying Naked barley root rot diseases pathogen pathogenicity test.The incidence of beaker of water-agar method was higher than that of the potted method,and significant difference.But after correlation analysis showed that the two pathogenic determination methods was significantly related,which suggested that two methods had the same result trend to determine the incidence and the index of disease.(5)The plate confrontation culture method and fermentation method were used for screenning anti-bacteriostasis strains.The result showed that Streptomyces acidiscabies AP11 was a potential anti-pathogens to Naked barley root rot diseases.(6)The Fusarium equiseti genome was assembled by primary and senior assembly in Illumina Hiseq4000 platform and Pac Bio platform,respectively.The result showed that the assembly had slightly different in different platforms,but no significant difference was found.Genome size was 40.55 Mb.GC content was 47.92%.There were 16 chromosomes.And the major gene length were 200-999 nt.(7)Many genes related to Fusarium equiseti D25-1 biological process were found by gene functional annotation,such as cell process,metabolism,molecular function and so on.Many genes related to Fusarium equiseti D25-1 pathogenicity were found by the carbohydrates relevant enzymes comments,PHI notes,cytochrome P450 annotation.Genetic distance was found by comparative genomics analysis,the Fusarium equiseti D25-1 and Fusarium pseudograminearum were the most closely related in the group,followed by Fusarium avenaceum,but Bipolaris sorokiniana was the least related in the group.(8)The field rhizosphere soil enzyme activity between healthy and diseased Naked barley were measured.The result showed that Naked barley root rot diseases occurrence caused its rhizosphere soil catalase,sucrase,urease and reduced alkaline phosphatase activity,but cellulose enzyme activity was risen.The incidence of Naked barley root rot and sucrase,urease activity were significantly and negatively correlated.(9)The Naked barley rhizosphere soil microbial biomass and microorganisms number of healthy field and diseased field were measured by spread plate method.The result showed that Naked barley root rot diseases caused its rhizosphere soil metabolic processes and the change of soil microbial community structure.The Naked barley root rot diseased fields rhizosphere soil microbial biomass nitrogen and phosphorus were decreased,the amount of bacteria and actinomycetes were decreased,too.But the fungi number was increased.(10)The Naked barley rhizosphere soil 16 S r DNA and 18 S r DNA microbial of healthy fields and diseased fields were tested by high throughput sequencing method,which found that Naked barley rhizosphere soil bacteria and fungi community structure were changed in phylum,class,order,family and genus by root rot diseases occurrence.Compared with healthy Naked barley rhizosphere soil microbial community structure.The more root rot disease,the greater differences in Naked barley rhizosphere soil microbial community structure were.The Naked barley rhizosphere soil microbial community structure varied in different growth period of Naked barley and region,too. |
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