The Application Of Composite Nano-selenium Drug Loading System In Prevention And Treatment Of Plant Grey Mould

Grey mould is a common crop disease caused by the infection of Botrytis cinerea(B.cinerea),which exists in various plants such as vegetables,fruits,flowers and even fruits.Globally,it has caused approximately US $1.1 billion in annual economic losses,while the cost of controlling grey mould has reached US $1.26 billion per year.B.cinerea can infect various tissues of the plant,including petals,fruits,leaves and stems through stomata or wounds and penetration,and then gradually show symptoms.In addition,due to the low temperature latent characteristics,B.cinerea can also cause serious damage to plants and fruits during storage,transportation and sales.At present,the main method used to control grey mould is chemical therapy,but long-term use of high doses of fungicides will lead to high residue,environmental and food pollution,and even make the strains resistant.Based on the above research background,two functionalized selenium nanosystems were designed and synthesized for the control of plant grey mould,aiming to develop new nano-pesticide which can replace traditional agricultural chemicals.Among them,the mesoporous selenium nanostructure was used for the loading of effective drugs.Based on the microenvironment of plant grey mould and the change of light temperature,they can achieve the precise release of drugs and the efficient killing of B.cinerea,and reduce the application of traditional pesticides and its damage to the environment.This article is divided into three chapters.In chapter 1: We firstly elaborated the symptoms and harms of grey mould,and introduced the pathogenic mechanism and characteristics of B.cinerea.Subsequently,the main measures for the prevention and treatment of B.cinerea.were discussed,and the intelligent responsive materials used in nano-pesticides and their application progress in plant diseases,insect pests and weeds were also summarized.Finally,the purpose and significance of this topic were explained..In chapter 2: The key to control grey mould is to prevent B.cinerea in advance and grasp the dosage and timing of drugs.Herein,we prepared mesoporous nano-selenium(MSe NPs)with high loading efficiency by CTAB template method,combined with antifungal drug Thiophanate-Methyl(TM)and p H-responsive polyacrylic acid(PAA)to construct composite nano system(TM@MSe@PAA NPs)which used as the control agent for plant grey mould.TM@MSe@PAA NPs can response to the release of TM to effectively kill B.cinerea under the condition of p H reducttion caused by the infection of B.cinerea.At the same time,compared with TM alone,TM@MSe@PAA NPs have good water solubility,and long-term application in crops without significantly affect their growth and development.In addition,TM@MSe@PAA NPs showed low-dose and high-efficiency antifungall effects in vitro and in vivo experiments on tomato and grape plants,which inproved the photosynthesis efficiency of plants to some extent.The prevention-inhibition integrated nano-selenium delivery system TM@MSe@PAA NPs designed in this chapter have showed good effects in defense and resistance to B.cinerea,and have potential application value in controlling plant grey mould.In chapter 3: Grey mould caused by B.cinerea is very destructive to the fruit,causing serious damage to its appearance and quality.We used temperature-responsive material Low Melting Point Agarose(LA)to combine MSe NPs with drug Iprodione(Ipr)loaded to construct the temperature-sensitive composite nano-gel(Ipr@MSe@LA NPs).As a biodegradable material,LA has a large surface area that can adhere to fungus for capturing,and can rapidly soften and release Ipr when the temperature rises.In the in vitro antifungal test,Ipr@MSe@LA NPs could effectively inhibit the production of B.cinerea colonies,and adhere to the surface of B.cinerea,achieving the effect of capturing fungus and killing them.In addition,in the in vitro fruit storage test,Ipr@MSe@LA NPs could increase the storage time of strawberries,achieving similar fresh-keeping function,and enhance the photosynthesis related fluorescence parameters of strawberry plants with good biocompatibility.The temperature-sensitive composite nano-gel Ipr@MSe@LA NPs designed in this chapter have excellent effects on controlling strawberry grey mould and prolonging the storage time of fruits,and is expected to become an effective strategy for controlling plant grey mould.