Biocontrol Potential Of Chaetomium Globosum Against Fusarium Spp.-the Pathogenic Fungi Of Panax Notoginseng Root Rot Diseases

The root rot disease is very serious in plantation of Panax notoginseng(Burk)F.H.Chen,and there is no effective approaches to treat the disease.Therefore,the development of notoginseng industry has been threaten by the reduced production owing to the disease.In our preivious research,Chaetomium spp.presented stronger biocontrol effect against the disease,inferring to its potential application in planting notoginseng.In this paper,the isolate Chaetomium globosum YIM PH30719 with the highest activity against the pathogenic fungi Fusarium oxysporum,F.solani,F.flocciferum was selected for further investigations.qPCR method was employed to survey the colonization ability of C.globosum YIM PH30719,and the effects on the pathogenic F.oxysporum.The combination biocntrol efficiency with some common used fungicides was also investigated inthis study.The obtained results were summarized as following.1.In the confronting tests,C.globosum YIM PH30719 could surpressed the growth of the main pathogenic fungi F.oxysporum,F.solani,F.flocciferum which are the causaul agents of notoginseng root rot diseases,with a inhibition rate more than 90%.The fermentation extract of C.globosum YIM PH30719 also showed obvious inhibition to the tested fungi.2.Five commonly-used fungicides–mancozeb,procymidone,iprodione,polyoxins and thiophanate-methyl/thiram,were employed to investigate the toxicity against C.globosum YIM PH30719 and the pathogenic F.oxysporum.At the concentration of 400 mg/L,polyoxins and thiophanate-methyl/thiram could completely inhibited the spore's germination of YIM PH30719,while mancozeb,procymidone and iprodione with the inhibitive rate of 97%,85%and 86%,respectively.In the radical growth tests,thiophanate-methyl/thiram presented the strongest activity against YIM PH30719 and F.oxysporum with growth-stop at the concentration of 20 mg/L,and showed the inhibition rates of 43%and 11%,respectively,at the concentration of 0.6 mg/L.At the concentration of 400 mg/L,the growth inhibition rates of mancozeb,procymidone,iprodione and polyoxins against YIM PH30719 were 100%,6%,78%and 59%,respectively,while their rates on F.oxysporum 33%,43%,68%and 55%,respectively.3.The results of qPCR showed that C.globosum YIM PH30719 could colonize ing the soil cultivated with 3-year-old notoginseng plants and control the concentration of F.oxysporum with the same efficiency as the combined use of fingucides applicated in the normal agro-management.In the seedling(1-year-old notoginseng)soil,C.globosum YIM PH30719 also could colonize under the condition of application of fungicides,and the concentration began decline after 45 d colonization.In the control experiments,the concentration of F.oxysporum was constant with a concentration of 10~5~10~6(gene copies/g dry soil)under applicating the combined fungicides.In the experiments,the concentration of F.oxysporum changed with different curves.It rose at beginning and declined with the combined application of C.globosum YIM PH30719 and procymidone/iprodione,declined within 75 d to 10~2(gene copies/g dry soil)with C.globosum YIM PH30719 and mancozeb/polyoxin,and also presented a decrease with C.globosum YIM PH30719.Therefore,C.globosum YIM PH30719 should be a potential biocontrol agent that could be applicated with chemical fungicides.