The Species Diversity Of Botryosphaeria Pathogen From Poplar Canker In Shandong Province

Poplar is a major tree species for the development of four-side greening,farmland shelterbelt and fast-growing and high-yield timber forests in Shandong Province and even in northern China.It plays a key role in the protection of economic,social and ecological environment of Shandong province.With the continuous expansion of the planting area of poplar plantations and the simplification of varieties,poplar canker disease is getting worse,which seriously affects the healthy and sustainable development of poplar plantations in Shandong Province.The fungus Botryosphaeria is the main cause of poplar canker disease.In order to clarify the species diversity of poplar cankers in Shandong Province,this study carried out research on the culture,morphology,molecular biology and pathogenicity of pathogens,and the research results are as follows:1.The experiment collected,isolated and purified the pathogens of 107,108,110 poplar cankers from 16 cities in Shandong Province.A total of 78 specimens were collected,and 52 strains were obtained ford separation and purification.2.According to the color,size,agglutination degree,pigment and colony edge characteristics of 52 kinds of bacteria,52 tested strains were divided into 5 characteristic types.According to the characteristics of fruiting bodies on the PDA medium,the canker was found.Most of the fruiting bodies are black or grayish white,superficial,semi-buried or buried,solitary or concentrated,mostly spherical or oblate,individual strains are solitary,and other tested strains are solitary or concentrated.Clonal fruiting bodies can produce two types of conidia: large conidia and small conidia,and two strains of individual strains are mixed.The conidia of Sdau18-40 strain in the test strain was brown,and the conidia of Sdau07-159 strain was light yellow at first,then turned into light brown to dark brown,and the conidia of other strains were colorless.3.Setting 8 temperature gradients from 5 ℃to 40℃ at the interval of 5℃,the growth temperature of mycelium was found to be in the range from 5 ℃to 40℃,and the optimum temperature was 25℃.4.ITS,β-tubulin,EF1-α,Lsu,Ssu,Frpb2 6 specific primers for PCR amplification,sequence alignment,combined with single gene or multiple gene sequences,combined with the culture and morphological characteristics of the pathogen.52 tested strains were identified as B.dothidea,B.obtusa,B.rhodina,of which 48 strains were B.dothidea,accounting for 92% of the tested strains,and were the dominant species of poplar canker in Shandong Province.B.rhodina and B.obtusa each accounted for 4% of the strains,which were sporadic species of poplar canker in Shandong Province.Phylogenetic analysis showed that B.dothidea was closely related to B.obtusa and B.rhodina,while B.obtusa and B.rhodina were closely related.Meanwhile B.dothidea was found to have intraspecific differentiation.5.The paper selected the representative strains with the most typical pathogens in culture,morphology and molecular biology,and the method of inoculation of apple fruit by artificial stab wounds was used to determine the pathogenicity of different kinds of pathogens.The results showed that there is difference in pathogenicity among the 3 pathogens of poplar cankers.B.rhodina is the most pathogenic,B.dothidea is medium,and B.obtusa is the weakest.In summary,The experiment clarified the species and diversity of poplar cankers in Shandong Province,and only three species of pathogens caused by poplar canker disease in Shandong Province were found.The above research results provide a theoretical basis for the scientific prevention and control of poplar canker disease in Shandong Province in the future.