Identification Of Germplasm Resources For Anthracnose Resistance(Diospyros Kaki Thunb.)and Screening Of Disease-resistance Related Genes DkWRKY In Persimmon

Persimmon(Diospyros kaki)is a traditional fruit with rich vitamins and minerals,which can be eaten directly or processed deeply..Anthracnose of persimmon as a common fungal disease occurred frequently in production parks all over the country,which seriously affected the development of industry of persimmon and the economic income of fruit farmers.On the basis of field investigation,the occurrence rule of anthracnose of persimmon was studied.It will lay a theoretical foundation for screening and utilization of resistance resources and breeding for resistance to persimmon in the future.At the same time,WRKY transcription factors related to disease resistance were screened,their relative expression levels were measured and analyzed,and the key genes of salicylic acid synthesis were quantitatively analyzed.The results are as follows:1.Observe the symptoms of persimmon anthracnose infection in different tissue parts.In 2021-2022,the anthracnose of national persimmon germplasm resource nursery was studied.Causing widespread disease.The isolation and identification of persimmon anthracnose were conducted based on the morphological characteristics,multi-gene sequence cluster analysis and pathogenicity detection.It was comprehensively identified as Colletotrichum horii.2.Field investigation of persimmon germplasm resources showed that persimmon fruits were more susceptible to anthracnose than branches.According to the severity of disease,persimmon fruits were divided into five resistance levels: high susceptibility,moderate susceptibility,susceptible,medium resistance and high resistance.Forty-three persimmon varieties were identified,including 8 highly resistant varieties,4 resistant varieties,5medium resistant varieties,3 susceptible varieties and 23 highly susceptible varieties.Twenty varieties were selected from the identified resistance resources,and their agronomic characteristics were analyzed.The sweet persimmon varieties such as ’Youhou’ and ’Taishuu’had strong resistance to anthracnose,which had great value in production and application,and could be used as materials for cross breeding of sweet persimmon varieties.3.Real-time quantitative fluorescence(q RT-PCR)analysis of the changes in the expression of resistance regulatory factors after inoculation of anthrax infection solution in the new shoots of the highly resistant variety ’Jixinhuang’ and the highly susceptible variety’Fupingjian Persimsima’ showed that the relative expression levels of two Dk WRKY genes were significantly different,namely Dk WRKY1-like,Dk WRKY21;WRKY gene sequence and protein structure analysis were cloned.Both WRKY proteins contained significant WRKY conserved domain.Subcellular results showed that Dk WRKY is a transcription factor located in the nucleus.After the infection of pathogens,the lignin content in the branches of the two varieties increased,and the lignin content in the highly resistant varieties was higher than that in the highly susceptible varieties.The increase of lignin content in plant tissues enhanced the resistance to anthracnose.After the infection of pathogens,plants activated the defense response through the salicylic acid(SA)signaling pathway.Real-time fluorescence quantitative analysis showed that the relative expressions of key genes of salicylic acid(SA)anabolic pathway Dk PAD4,Dk ISC2,Dk PAL1,Dk NPR1 and Dk TGA1 were induced to increase after the infection of pathogen.