| Beauveria bassiana is one of the most widely used fungi for pests control in agriculture and forestry.In recent stduies,it has been found that B.bassiana had the ability to colonize in plant tissue,promoted plant growth and development,and improved plant resistance against stress.However,most studies on the use of B.bassiana to induce the resistance of host plants have focused on plant leaf diseases,while few on soil-borne diseases.Sclerotinia sclerotiorum is an important pathogen causing plant sclerotinia disease,and many biocontrol fungi have good biocontrol effect on it.However,it has not been reported to use B.bassiana to control the disease.In order to understand the colonization ability of B.bassiana in rape(Brassica napus L.)and sunflower(Helianthus annuus L.)and its resistance agaisnt Sclerotinia sclerotiorum,a plant-b.bassiana symbiosis was constructed by seed soaking and root irrigation,respectively.The effect of B.bassiana on the growth of sunflower and rape was evaluated by measuring the chlorophyll and the height of tht two tested plants,and the disease incidencewas analyzed,and the amont of B.bassiana and S.Sclerotiorum was detected by fluorescent quantitative PCR,to identify the distribution of the both fungi in plants.The main results obtained in this experiment are as follows:1.Seed soaking and root irrigation enabled the B.bassiana spores successfully colonize in sunflower and rape plants and promoted plants growth.The highest colonization rates of B.bassiana in sunflower and rape were 36.67% and 33.33%respectively after seed soaking,and which were 53.33% and 43.33% respectively after root irrigation,and the germinated hyphae of B.bassiana could be observed in the plants after colonization.Compared with the control group,the height and chlorophyll content of sunflower and rape plants treated with B.bassiana were increased.In the pot experiment of sunflower,the maximum increase of plant height was 20.27%(P<0.05,F=2.575),and the maximum increase of chlorophyll was 13.26%(P<0.05,F=29.506),and which were 20.47%(P<0.05,F=17.353),and 8.83%(P<0.05,F=25.288)in the pot experiment of rape.2.The disease incidence caused by S.sclerotiorum could be reduced via spores of B.bassiana colonization in both sunflower and rape.In the pot experiment of sunflower,the incidence of the disease was decreased by 50.00%(P<0.05,F=36.200),and which was 30%(P<0.05,F=21.000)in the pot experiment of rape.The results also showed that the colonization of B.bassiana could delay the symptom of the disease.3.The results showed that the content of B.bassiana in the leaves of infected plants increased relatively when the plants were infected by the pathogens,which mean that B.bassiana was actively recruited to soil when plants were stressed by pathogens.B.bassiana played an antagonistic role in S.sclerotiorum infection,thus inhibiting the proliferation of the pathogen,induced the plant disease resistance.This study clarified the endophytic characteristics of B.bassiana and its resistance against plant diseases,and discussed the distribution of B.bassiana and pathogen in host plants under biological stress.This study broadens the scope of the control of plant diseases by entomopathogenic fungi,and lays a foundation for further exploring the relationship between entomopathogenic fungi and plants,at the same time,it can provide guidance for the rational use of bio-control microorganisms to control plant diseases. |
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