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Identification and Pathogenic Analysis of Plant Pathogenic Fungi and Mycoparasited in Zhoukou

Author: ShiYang
Tutor: YangQingXiang;LiChengWei
School: Henan Normal
Course: Microbiology
Keywords: Erysiphauceae A.quisqualis S.sclerotiorum single-spore isolation ITS identification diseasetest
CLC: S476
Type: Master's thesis
Year: 2012
Downloads: 70
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Powdery mildew and Sclerotinia sclerotiorum are two kinds of the most important plant diseases inChina. Ampelomyces quisqualis is an important mycoparasite of powdery mildew fungus with resistanceagainst most used chemical fungicides, which has potential to control powdery mildew. Because differentaccessions of A.quisqualis could show genetic differences, and the potential application of A.quisqualis isaccession dependent. Therefore, screening A.quisqualis resources to obtain potential new accessionssuitable for local application on fungal disease prevention is important. S.sclerotiorum is a filamentousAscomycete fungus with a wide host range, which causes server losses of the rapeseed production,especially in the southern areas. The disease at the year of serious outbreak can infect to50-80%of plants,which is one of the most important disease of rapeseed causing serious damage to rapeseed production bothon yield and on quality.In this paper, characteristics of A.quisquals in Zhoukou and interaction between the A.quisquals andpowdery mildew fungi were investigated. Characteristics of S. sclerotiorum in Zhoukou and it’s interactionwith the susceptible and tolerant genotypes of rapeseed were studied.The results are as following:1. Powdery mildew appearing in colonies of white patches prevalently on leaves of tomato was foundin Zhoukou of Henan Province. The microscopic morphology and molecular identification of the pathogensthat Cause this disease were studied in terms of internal transcribed spacer (ITS) sequence and phylogenetictrees. The conidia which were borne singly, cylindrical, or ellipsoid-cylindrical without branch wereobserved under the scanning electron micriscipy (SEM). The ITS sequence is highly homologous to ITSsequences from O.neolycopersici(AB163916、AB094991), It draws a conclusion that the pathogen oftomato powdery mildew in Zhoukou belongs to O.neolycopersici.2. An strain of A.quisqualis was isolated from powdery mildew infected rose balsam (Impatiensbalsamina L.) in Zhoukou city of Henan province with the method of single-spore isolation. Themorphology and microscopic analysis indicated that the isolated stain was A.quisqualis. Universal primersITS1and ITS4for fungi were used to amplify the internal transcribed spacer (ITS) region of the isolated strain, which resulted in a578bp band. The PCR product was sequenced and analyzed by using BLAST,which showed100%homology to AQ in Germany and USA. It further proved that the isolated strain was A.quisqualis. A.quisqualis was inoculated on powdery mildew of Euonymus japonicus, after one-weekinoculation, it showed that the powdery mildew gradually become yellow or shallow brown, and thepowdery mildew gradually disappear, indicating that the A. quisqualis isolate of powdery mildew on RoseBlasam from Zhoukou area can be used for the prevention of powdery mildew.3. The result showed that A.quisqualis can grow at temperatyre of10-30℃and the optimaltemperature was20℃. The pH value of5-10, the optimal pH value for its growth and sporulation were at7.The optimal C source was lactose, and the optimal N source was peptone. Light could effectively stimulateAQ growth and sporulation.4. A strain of S. sclerotiorum was isolated from rapeseed in Zhoukou city of Henan province with themethod of single-spore isolation. The morphology and microscopic analyses indicated that the isolatedstain was S. sclerotiorum. Universal primers ITS1and ITS4for fungi were used to amplify the ITS regionof the isolated strain, which resulted in a640bp band. The PCR product was sequenced and analyzed byusing BLASTn, which showed100%homology to found S.sclerotiorum. It further proved that the isolatedstrain was S.sclerotiorum.5. The result showed that S.sclerotiorum can grow at temperatyre of15-35℃and the optimaltemperature was25℃. The pH value of5-10, the optimal pH value for its growth and sporulation were at8.The optimal C source was sugar, and the optimal N source was yeast extract. Light could effectivelystimulate S.sclerotiorum growth and sporulation.6. Fungal suspension of S. sclerotiorum was used to inoculate susceptible and tolerant phenotypes ofrapeseed. Four days after inoculation, the infected leaves were stained with trypan blue to study themechanism difference of responses to S. sclerotiorum by different rapeseed genotypes. It indicated that noobvious difference between two genotypes, except that the length of hypha on tolerant genotype wereshorter than those on susceptible genotype of rapeseed. The infection processes of S. sclerotiorum ontomato and Arabidopsis leaves were also investigated. It indicated that S. sclerotiorum can infect tomatoand Arabidopsis. Further study will be carried out to test whether AQ can prevent the growth of S.sclerotiorum.

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CLC: > Agricultural Sciences > Plant Protection > A variety of control methods > Biological control
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