The Screening And Preliminary Antagonistic Mechanism Of Kiwi Fruit Soft Rot

Kiwi soft rot is one of the major postharvest disease of kiwifruit,which could cause serious financial loss.It is prevalent that the chemical microbicide be used in present market,however people pay increasing attention to the reagent residual and the resistance of pathogen caused by the use of chemical microbicide.On the contrary biological control is healthy,effective and getting more and more attention.The purpose of this reseach is to screen the antagonistic microorganism of kiwi soft rot,as well as to study the preliminary antagonistic mechanism and authenticate the biocontrol strain filtrated.The experimental results as follows:1.We selected the biocontrol strains which effectively against kiwi soft rot.We found 5 strains which could inhibit the growth of fungus of kiwi soft rot by in vitro experiments(strain H-Z and S1-4,strain bd-5-1,strain Wei 1 and Wei 3).On the basis of rDNA ITS sequence analysis,strain H-Z and S1-4 both were identified to be Wickerhamomyces anomalus,the strain of bd-5-1 was authenticated to be Cyberlindnera fabianii,Wei 1 and Wei 3 were both authenticated to belonged to Bacillus through rDNA 16 S sequence analysis.2.Through the in vivo experiment of strain H-Z,we found that when the concentration of strain H-Z is 1.0×108 CFU/mL,the rotting rate is only 36.7%,compared with the control group of 100% rating,which illustrating H-Z has the significant antagonistic effect against kiwi soft rot.By studying the antagonistic mechanism we found that firstly,strain H-Z can inhibit the growth of pathogen through being parasitic on the hypha of kiwi soft rot both in vitro and in vivo.Secondly,there exists competitive effect of nutrition between the strain H-Z and soft rot.Glucose,sucrose and maltobiose et al.have been used both by strain H-Z and kiwi soft rot,they don't use citric acid neither.The nitrogen sources both H-Z and the pathogen used are asparagines,actamine and glutamic acid et al..According to the species of monosaccharides and amino acids belonged to the kiwi fruit,we can draw the conclusion that the strain of H-Z and the pathogen co-compete glucose and mannose,they have no competition towards nitrogen source.3.There exists nutrition competitive effect between the strain of bd-5-1 and kiwi soft rot.According to the species of monosaccharides and amino acids belonged to the kiwi fruit,the carbon source that bd-5-1 and soft rot co-compete are glucose,and they both use 3 kinds of amino acids,which are glutamic acid,proline and tyrosine respectively.Therefore we can conclude that there exists carbon and nitrogen source between the strain of bd-5-1 and kiwi soft rot.