| Cordyceps cicadae is an important entomopathogenic fungus,which is regarded as a traditional Chinese medicinal material and an important health food for mass industrial production.The solid culture substrate containing a large amount of mycelium was uselessly discarded when the fruited bodies of C.cicadae were harvested.A valuable utilization of the harvested solid culture substrate of C.cicadae（HSC）will improve the comprehensive economic benefits of the C.cicadae industry.C.cicadae as a rhizosphere fungus may pose effects on plant growth and biological stress resistance.In this study,HSC from industrial production of C.cicadae was tested as a biological fertilizer and biological plant growth promotor to observe the effects of adding HSC on the growth and pest resistance of tobacco（Nicotiana tabacum）.Physiological properties as well as metabolites and metabolic pathways of C.cicadae against tobacco were analyzed.The main results were as follows:The HSC showed a significant promoting effect on tobacco growth in the whole growth period.Plant height,leaf length,leaf width,and number of tobacco leaves increased by 18.46%,33.56%,21.02%and 93.29%compared with the control group,respectively,on the 35thday after fungal inoculation.At the same time,compared with the control,the number of tobacco seeds treated with HSC increased by 152.14%,and the promotion of reproductivity growth reached a very significant level.The addition of HSC had no significant effect on the fungal infection incidence of Tobacco botrytis.At the same time,the treatment posed some positive effect on alatae aphid attraction,which led the proportion of alatae aphids in the treatment was significantly higher than that in the control.Quantitative determination of chlorophyll and photosynthesis of tobacco leavesrevealed that the chlorophyll a and chlorophyll b contents in tobacco leaves of HSC addition treatment were significantly increased by an increase rate of 53.56%and 48.09%,respectively.HSC treatment also led to a significant improvement in photosynthetic efficiency,and intercellular CO2concentration,while a very significant negative correlation to stomatal conductance and transpiration rate.Further metabolomics study showed that there were 778 different metabolites in tobacco leaves between the HSC treated group and the control group,among which 466were up-regulated and 312 were down-regulated,mainly including organic acid compounds,lipid compounds,heterocyclic compounds,organic oxygen compounds,etc.Among them,organic acid compounds,lipid compounds and some other differential metabolites of tobacco were related to tobacco quality and flavor.The HSC treatment up-regulated a large number of tobacco flavor substances,by which the quality and aroma of tobacco leaves were significantly improved.The relationship between organic acid compounds,lipid compounds,heterocyclic compounds and the aroma compounds of tobacco as well as their metabolic pathway were discussed in more detail.The HSC treatment significantly improved vegetative growth and reproductive growth of tobacco as well as tobacco leaf quality. |
