Research Of Identification Of Mulberry Fruit Pathogencic Fungi And Its Postharvest Microbial Preservation Techniques

Mulberry fruit belongs to berries,riched in nutrition and bioactive compounds, which is known as one of the best healthy fruit in the 21 st century. The important reasons which cause the yield loss of mulberry fruits are pre-harvest popcorn disease and its post-harvest saprophytic disease. Identification pre- and post-harvest pathogenic fungi of mulberry fruit,antagonism of biocontrol microbial on rot pathogens of mulberry and its effect onn quality of postharvest mulberry by postharvest treatment are the three aspects of this study. The main results as follows:(1) Fruiting body were cultivated and identifed of sclerotia. Mulberry sclerotia were collected from the mulberry orchard, then used to carpogenic germination. There were three kinds of sporophore according morphology structure. The r DNA-ITS sequences were obtained by using ITS1 and ITS4 primers, the strain with Max identities are Ciboria shiraiana strain(99%), Scleromitrula shiraiana strain(97%), Ciboria carunculoides strain(98%) by Blast homology analysis in NCBI database..(2) Three saprophytic fungi were isolated. Fungi were isolated from postharvest rotting mulberry fruit, and their pathogenicity were tested accoding koch's postulates. They were fungus of Botrytis spp, Rhizopus stolonifer and Mucor spp.accoding to morphology ananlysis and Blast homology analysis of r DNA-ITS sequences in NCBI database.(3)TR16,TR16 and BS are antagonistic to saprophytic fungus of mulberry fruit in vitro. Accoding the result of the dural culture method and inhibition growth of rotting fungi by culture filtrate, the mechanisms the pathogen affected by Trichoderma harzianum TR16,Trichoderma longibrachiatum TR66 were by competition, parasitism and secondary metabolites,1% CTS as control to evaluate the antifungal activity of TR16 and TR66 cultural filtrate. Colonization of TR16 and TR66 were superior than pathogen(?50%).By dual culture method, the inhibition rate of TR16 and TR66 on hypha growth of rot fungus were between60% and 80%, the inhibition rate of BS on the Botrytis spp strain was 58.02%.The inhibition rate of the raiculus of hypha growth of saprophytic fungi RF1, RF2 and RF3 by 1% CTS was 30.12%,24.53% and 18.75% compared with control, respectively. TR66 cultural filtrate showed highest inhibition rate, significantly higher than 1%CTS and TR16 cultural filtrate treatment(p<0.05). TR16 cultural filtrate, compared with 1%CTS, had significant inhibition effect on RF2 strain, no significantly diference between RF1 and RF3.(4) Effect of spore suspension and cultrure filtrate of TR16, TR66 and BS on the postharvest quality of mulberry fruit was researched. 1%CTS as the experiment control,distilled water as the blank control, were used to treate the postharvest mulberry fruit to study the effect of different treatments on mulberry quality. The result showed that % CTS could inhibit rotting rate, weight loss rate, the decline of the content of total soluble solids(TSS) and ascorbic acid(AAC), bioactive compound content, and decline of DPPH radical scavenging capacity of mulberry fruit compared with blank control. The content of TSS and AAC of mulberry can significantly inhibited by TR66,BS treatmenst. Bioactive compounds- anthocyanin, flavonoids and phenolics could be induced by elicitors in postharvest fruit. Three kinds of bioactive content of mulberry fruit increased firstly, and then decreased during storage. After 21 d storage, anthocyanin content of CTS, TR16, TR66 and BS treated mulberry fruit significantly incresed when compared with the blank control(P<0.05), the content of phenolics of mulberry fruit treated by culture filtrate of three biocontrol microbe were significantly incresed when compared with the blank control(P<0.05),quality of mulberry treated with the culture filtrate of TR66 was best,all of the quality index were significantly higher than 1%CTS treatment.This study identified the pathogenic fungus of two kinds of mulberry fruit disease,firstly. Secondly,the feasibility of application of biocontrol microbial on the mulberry fruit preserbation was studied primarily by examination the antagonism of biocontrol agents to the rotting fungi and its influence on the quality of mulberry fruit. We aimed at provide the theory and practice basis on the mulberry disease control and its postharvest microbial preservation technology.