Isolation,Identification And Antagonism Of A Nthracnose And Endophytic Bacteria From Tree Peony

Peony is a perennial deciduous shrub of the genus Paeonia in the family Paeoniaceae,with high medicinal,ornamental and oil values.In the long-term artificial cultivation process,the diseases and insect pests of peony are becoming more and more serious,which affects the economic value of peony.In the hot and humid summer,the leaf diseases of peony caused by anthracnose are particularly prominent.The application of chemical pesticides has a certain control effect,but it is easy to make the anthracnose bacteria resistant to resistance,and it will also destroy the soil structure.With the new requirements put forward by the sustainable development of agriculture for the prevention and control of traditional diseases,microbial pesticides have been widely concerned by researchers due to their advantages of high efficiency,low toxicity,environmental protection and wide sources.In this study,the pathogenic bacteria were isolated and identified from peony anthracnose samples collected from the flower base of Hunan Agricultural University.The antagonistic strains of P.anthracis were isolated,screened,and identified from the stems and roots of healthy peony,and their antagonistic ability was evaluated,and their growth-promoting properties on plants were explored.In order to lay a foundation for further research on the interaction between pathogenic bacteria and endophytes,and provide a new way for the control of peony anthracnose.The results of this study are as follows:(1)Through the methods of tissue isolation,pathogenicity detection,morphological and molecular biology identification,the main pathogen of peony anthracnose collected in the flower base of Hunan Agricultural University was identified as Colletotrichum gloeosporioides.(2)The endophytic bacteria were isolated from healthy peony roots and stems by the dilution coating plate method,and a total of 64 endophytic bacteria were isolated.Screening,the results showed that strains FJ1.3,ZJ1.4,ZJ1.5,XG1.4 had good inhibitory effect on pathogens,and the growth inhibition rates were 51.39%,48.1%,41.67% and 36.11%,respectively.(3)After morphological,physiological and biochemical characteristics and molecular biology identification,strain FJ1.3 is Bacillus subtilis,strain ZJ1.5 is Bacillus amyloliquefaciens,strain ZJ1.4 is Bacillus tequilensis,strain XG1.4 is Bacillus alcalophilus.(4)The growth-promoting ability of the four most antagonistic endophytic bacteria was measured.The results showed that all four strains had the ability to secrete IAA and fix nitrogen.Among them,strain ZJ1.5 had the strongest ability to secrete IAA,and the concentration of IAA was as high as 17.02 mg/L,the ability of strain FJ1.3 to secrete auxin was the second,which was 16.94 mg/L.None of the four antagonistic bacteria had the ability to dissolve phosphorus.(5)The antibacterial test of the fermentation broth of the four antagonistic bacteria after fermentation and the control effect of the peony leaves on the peony anthracnose were determined,and it was again proved that the four antagonistic bacteria had the inhibitory effect on the peony anthracnose.The results of the fermentation broth bacteriostatic test showed that all the four antagonistic bacterial fermentation broths had bacteriostatic effects on peony anthracnose,and the most bacteriostatic strain was FJ1.3,with a bacteriostatic rate of 35.13%.The leaf lesions of the peony leaves inoculated with the fermentation broth of the four strains were significantly smaller than those of the clear water control.After 5 days of inoculation,the control effect of the strain FJ1.3 on peony anthracnose reached 47.06%.Followed by ZJ1.4,the control effect was 22.48%.(6)The metabolic secretions of antagonistic bacteria were measured,and the results showed that all 4 antagonistic bacteria could produce protease,and the strain ZJ1.5 had the highest enzyme yield,and the ratio of the diameter of the transparent circle to the diameter of the colony reached 5.67;the strain ZJ1.5,ZJ1.4 and FJ1.3 can all produce cellulase,among which strain FJ1.3 has the highest enzyme yield,and the ratio of the diameter of the transparent circle to the diameter of the colony reaches 22.50;none of the four strains has the ability to produce β-1,3-Glucanase capacity.To sum up,the pathogen of peony anthracnose is Colletotrichum gloeosporioides,strains FJ1.3 and ZJ1.5 have good inhibitory effect on pathogenic bacteria,have good IAA production and nitrogen fixation ability,and can produce destructive effects on the cell wall of pathogenic bacteria of proteases and cellulases.