Screening And Biocontrol Efficacy Research Of Antagonism Yeast Synergistic Agent Against Postharvest Mango Anthracnose

Mango is a tropical fruit that is popular with consumers all over the world.Postharvest mango anthracnose,caused by Colletotrichum gloeosporioides(Penz)Sacc,is the major diseases of the mango postharvest industry,which seriously affect the sensory quality and economic value of mango,resulting in huge losses.Currently,prevention of postharvest anthracnose is mainly dependent on chemical fungicides,but its negative impact on the environment and human health,has become one of the issues of concern to the public.Biological control is the development direction of the fruit and vegetable diseases prevention and control,by antagonistic microorganisms to control diseases of fruits and vegetables has been hot research,conform to the national development strategy of green and environmental sustainability,in favor of the Antagonistic Yeast more by researchers,because of the Antagonistic Yeast with biocontrol effect is good,strong resistance,low nutrient requirements,low investment cost;generally does not produce toxins,not on human health and the natural environment harm;genetics and genetic transformation system of relatively clear in can by gene engineering technology to improve biocontrol effect.At present,the use of antagonistic microbial control of mango anthracnose disease at home and abroad are reported,but antagonistic yeasts prevention effect and chemical sterilization agent still has a large gap compared and the use of most of the Antagonistic Yeast in the analysis phase.In order to realize the commercial application of antagonistic yeasts and need to strengthen the separation and screening is more effective in inhibiting postharvest mango anthracnose pathogen of yeast,and how to improve the Antagonistic Yeast control effect is to put into commercial production using the key.The purpose of this research is to screen out effective antagonism yeasts,and screen out the safe and healthy chemical synergist to improve the effectiveness of the antagonistic yeast.At the same time,measuring the incidence of mango anthracnose,the fruit quality and the activity of disease-related enzyme to study its antagonistic effect.The results of the experiments were drawn as following:(1)A total of 71 strains of yeast were isolated from the rhizosphere soil of mango tree in Changjiang orchard of Hainan province.Through the method of confront culture,the yeast strain named 'LW' was screened out,which had the most antagonistic effect to Colletotrichum gloeosporioides,the inhibition zone diameter of it was 12.25mm.The vivo test showed that lesion diameter of mango fruits(cv.'Hongyu')treated by LW at concentration of 1.0×108 cfu/mL was only 11.67mm,it was much lower than the control fruits of 29.63mm,the antagonistic effect was very significant.Through the analysis of colony,cell morphology,and 26s rDNA sequence,LW was identified as Metschnikowia pulcherrima.(2)The experiment of inhibiting effect on natural disease by Metschnikowia pulcherrima showed that anthracnose disease index of fruits treated by Metschnikowia pulcherrima at concentration of 1.O×108 cfu/mL was only 9.2 under 25 ? after 20 days,and was 9.87 under 15 ? after 24 days,which are significantly lower than other concentration and control group.(3)Through the method of confront culture,AEB,FEB,HEB three combinations were screened out,which had the obviously positive effect to Metschnikowia pulcherrima against Colletotrichum gloeosporioides,the inhibition zone diameter of them respectively were 14.72mm,14.67mm and 15.15mm.(4)In vivo test showed that lesion diameter of mango fruits treated by AEB was only 9.13mm;it was much lower than other treatments.The experiment of inhibiting effect on natural disease showed that anthracnose disease index of fruits treated by AEB was only 4.12 under 25 ? after 20 days,and was 5.74 under 15 ? after 24 days,which was significantly lower than other treatments.Therefore,a combination of the CMC-Na,SA and MeJA were selected as the synergistic agent.(5)After studying on the application effect of AEB,AEB1(0.03%CMC-Na?20?g/mL SA?10? mol/L MeJA?Metschnikowia pulcherrima at concentration of 1.0×108 cfu/mL)was proved of having the most inhibiting effect on natural disease,better maintaining the quality of the fruit and delaying the maturity of the fruit's ageing process.AEB1 also obviously improved the activity of polyphenol oxidase,phenylalanin ammonia lyase,Chitinase and ?-1,3-glucanase of mango fruits at the same time.