Evaluation Of The Resistance Of Sichuan Walnut Varieties To Anthracnose And Study On The Correlation Of Its Leaf Inclusions

In order to select Sichuan walnut varieties with good resistance to anthracnose,this paper through morphology,rDNA-ITS sequence analysis and Koch identification to identify and verify the walnut anthracnose pathogen;Three kinds of evaluation methods were adopted,including field investigation,field artificial inoculation and indoor artificial inoculation.Comparing the advantages and disadvantages and reliability of these methods,we screened the best evaluation method and screened out walnut varieties(lines)with high resistance to anthracnose;The content changes of 8 kinds of leaf inclusions before and after inoculation with Anthracnose in field were measured,and the correlation between them and walnut resistance was investigated.The main results are as follows:1.The CN2016-05 fungi obtained from the leaf separation of the walnut anthracnose were analyzed by rDNA-ITS sequence,and the result was C.gloeosporioides,the fragment was 545 bp,the similarity rate was 99%,the login number was KC341951.1,and the morphological identification result was also C.gloeosporioides.2.In the 3 inoculation methods,the results of artificial inoculation leaves in the field and the fruits were inoculated indoors were the best.According to the results of field inoculation of leaves and indoor inoculation of fruits,10 varieties of high resistance to Walnut anthracnose were screened out: Chuanzao No.1,Shujiang No.1,Yanyuanzao,Panhe,No.200,No.71,Liaohe,No.64,No.92,Qingxiang.These walnut clones can be used as the excellent germplasm resources of walnut resistant to anthracnose,and are expected to breed new varieties.3.Before and after inoculation,the content(activity)of SOD,POD,PPO,chitinase and total phenol,proline and soluble sugar in 9 walnut varieties were significantly different.After inoculation,the content(activity)of POD,PPO,chitinase and soluble sugar increased.These 3 enzymes may be involved in the biochemical reaction against pathogenic bacteria,and the increase of soluble sugar may regulate the permeation potential of the leaves.4.Before inoculation,the chitinase of walnut varieties(lines)had a significant negative correlation with disease index,that is,the stronger the disease resistance of walnut,the higher the activity of chitinase.Chitinase activity can be preliminarily used as an auxiliary index of resistance.There is no significant correlation between the other 7 kinds of inclusions and disease resistance,which needs further study.