Effects Of Exogenous Melatonin And Selenium On Botrytis Cinerea Resistance Of Strawberry

Strawberries are susceptible to gray mold caused by Botrytis cinerea during planting,transportation and postharvest storage,and their yield and quality are seriously affected.In order to explore an effective and safe method for the prevention and control of strawberry gray mold,this experiment used’Hongyan’strawberry fruit as the material,inoculated with B.cinerea,during the white fruit period,and treated with different concentrations of exogenous melatonin（MT）and exogenous selenium（Se）.The control effect of MT and Se on strawberry gray mold,physiological and biochemical indexes,and the expression of disease resistance genes were determined to clarify the effects of exogenous MT and Se on strawberry gray mold resistance.On the one hand,it provides theoretical guidance for the prevention and control of strawberry gray mold in agricultural production;on the other hand,it provides some ideas for the subsequent application of MT and Se in improving plant disease resistance,and provides a theoretical basis for further use of its improved chemical fungicides.The main results are as follows:（1）By culturing B.cinerea on PDA plates with different concentrations of MT and Se,it was found that MT had no significant effect on the growth of B.cinerea,while Se 18mg·L^-1,24 mg·L^-1,32 mg·L^-1could directly inhibit the growth of B.cinerea.（2）The physiological and biochemical determination of strawberry fruit inoculated with B.cinerea showed that the infection of B.cinerea could increase the content of endogenous MT and salicylic acid（SA）in strawberry fruit,and increase the content of superoxide anion（O₂^-）and hydrogen peroxide（H₂O₂）in active oxygen metabolism.（3）Strawberry fruits were pretreated with different concentrations of MT and Se solutions,and then inoculated with B.cinerea to observe the incidence of strawberry gray mold.The results showed that 50μmol·L^-1 MT solution,18 mg·L^-1Se solution,and 50μmol·L^-1 MT and 18 mg·L^-1 Se combined treatment of strawberry fruits could better inhibit strawberry gray mold.（4）The physiological indexes of strawberry fruit treated with exogenous MT and Se were measured.It was found that MT treatment alone increased the soluble sugar content and also decreased the endogenous SA content of strawberry fruit.Se treatment alone could reduce the contents of anthocyanin,soluble sugar and ascorbic acid（Ascorbic acid,As A）in strawberry and delay fruit ripening;The combination of MT and Se increased the content of anthocyanin,soluble sugar and As A,and increased the resistance substances of strawberry fruit.Whether MT or Se alone or MT and Se combined treatment of strawberry fruit,can reduce the H₂O₂ content in the active oxygen metabolism.（5）By measuring the expression of key genes and resistance-related genes in anthocyanin pathway,it was found that B.cinerea could induce the expression of GLU gene and inhibit the expression of Fraa1 and SOD genes.MT alone could up-regulate the expression of F3H gene and inhibit the expression of Pru and GLU gene.Se treatment alone increased the expression levels of ANS,DFR,TT19,F3H,Pru,and Fraa1 genes in strawberry fruit.While MT and Se combined treatment increased the expression levels of ANS,CHS,DFR,TT19,CHI,MYB10,F3H,and inhibit the expressions of SOD and GLU genes in strawberry fruits.In this test,it was found that the infection of B.cinerea could increase the contents of endogenous MT and SA in strawberry fruit,and increase the contents of O₂^-and H₂O₂ in active oxygen metabolism.Secondly,the concentration of Se above 18 mg·L^-1 in PDA plate could directly inhibit the growth of B.cinerea while 50μmol·L^-1 MT solution,18mg·L^-1Se solution,and 50μmol·L^-1and 18 mg·L^-1 Se combined treatment could better inhibit strawberry gray mold.It provides a potentially effective method for the prevention and control of strawberry gray mold.