Species Identification And Virulence Differentiation Of Pathogenic Fungi Of Forest Tree Rot Disease In Xinjiang

To clarify the species of pathogens of forest rot disease in Xinjiang,and to study the morphological differences,genetic relationship and pathogenic differentiation of pathogens of different host sources,to provide a theoretical basis for the comprehensive prevention and control of forest rot disease under the ecological conditions of Xinjiang oasis.In this study,a large number of rot disease samples from different host sources and typical symptoms were collected,and the pure culture of rot fungi was obtained by Koch’s rule;Through morphological observation,combined with molecular biology methods,the species of rot disease pathogens from different host sources were determined;Finally,the pathogenicity differences of rot pathogens from different host sources were clarified by indoor in vitro shoot inoculation method.The main findings are as follows:1.81 rot disease strains from different host sources were collected and isolated.According to different culture characteristics,the 81 strains of rot disease were divided into 8 groups,namely,white difficult-to-produce colonies,white-prone colonies,light yellow colonies,light green colonies,dark green colonies,brown-green colonies,The yellow colony group and the brown colony group.Through the observation of fruit body morphology,the fruit bodies are divided into 4 types,namely single-chamber type,multi-chamber neatly arranged type,multi-chamber labyrinth-like non-shared chamber wall type and multi-chamber labyrinth-like shared chamber wall type type.According to the size of conidia,it is divided into macrospore group,mesospore group and microspore group.2.A phylogeny was constructed based on the ribosomal DNA internal transcribed spacer gene sequence(r DNA-ITS),transcription elongation factor gene sequence(EF-1α)gene,and RNA synthase second subunit gene sequence(RPB2)of the tested strains The results showed that the forest rot pathogens in Xinjiang mainly included Cytospora ambiens,Cytospora chrysosperma,Cytospora leucostoma,Cytospora pruinopsis,Cytospora parasitica,Cytospora ribis and Valsa malicola.3.Revealed the diversity of Ascocystis fungal hosts in Xinjiang.C.ambiens hosts apple trees and pear trees;C.chrysosperma has the most extensive host,including 19 hosts such as mountain peach,elm leaf plum,and walnut tree,among which 6 new hosts were discovered;The hosts of C.leucostoma are apricot,peach and elm plum;C.parasitica hosts crabapple trees;The host of C.ribis is birch;The host of the strain C.sp.to be identified is a cold-resistant rose;V.malicola Ailanthus and a newly discovered host species;C.pruinopsis hosts elm and one newly discovered host.4.The rot disease strains from different host sources are all pathogenic to poplar,but the virulence is significantly different.The virulence has nothing to do with the culture characteristics of the rot pathogen,but is related to the strain species.Among them,C.chrysosperma and C.ambiens are highly pathogenic strain;Finally,it was found that the disease spots increased with the decrease of the water content of the branches after the drought simulation treatment of the isolated branches,indicating that drought stress may have a promoting effect on the occurrence of rot.In summary,This paper clarifies the species of pathogenic fungi of forest tree rot disease in Xinjiang,supplements 8 new recorded hosts of Ascocystis fungus,enriches the geographical distribution of forest tree rot disease in Xinjiang,increases the polygene molecular data of pathogenic fungi of forest tree rot disease in Xinjiang,and verifies each strain.The differences in pathogenicity have laid a foundation for further research on forest rot disease in Xinjiang.