Pathogenic And Biological Characterization Of T-DNA Insertion Mutants In Colletotrichum Gloeosporioides Casual Organism Of Apple Anthracnose

The apple anthracnose leaf spot caused by C.gloeosporioides is an important disease of apple in recent years in China.16 T-DNA insertion mutants of C.gloeosporioides were selected from a mutant library which created through ATMT method,the pathology and biology characters were further studied.Through this study,the relative pathogenicity-associated genes were selected,the better condition for colony growth and sporulation were identified,and it is helpful for the further study on their pathogenicity mechanism and for the management of the disease.The main results of the study are as follow:Through inoculation test on wound apple fruit,5 pathogenicity related insertion mutants were screened out,among of them,mutants A4204,M44,A3638 and A1598 lost the pathogenic capability completely,mutant A1919 and A1643 produced slightly symptoms on wound apple fruits.Insertion mutant A3638 had poor colony growth in all medium,means that this gene is also positively control the vegetative growth.Sporulation of mutant A4204 increased obviously compared with wild isolate stj16,means the gene A4204 negatively control the conidia production,bioinformatics analysis and subcellular location of the protein A4202 identified its function on cell division;4 insertion mutants(M44,A2983,A3144 and G1183)strongly decreased the sporulation of the fungi,it means that they positively control the production of the conidia.Biology study indicated that: 1)the Rose Bengal Agar(RBA)medium decreased the mycelium growth,but it can increase the sporulation for most of the isolates;2)most of the isolates fit to a large p H range(from p H4.0 – p H8.0),but mutant A4204 doesn‘t grow well at p H4.0 and p H8.0,and mutant M44 just has optimum grew at p H8.0;3)12h light and 12 h dark condition stimulate the sporulation for most of tested mutants,but A1764 mutant more sporulated at regular dark condition.Based on the biology study,the best growing and sporulation condition for all the tested isolateswere found.All the mutants and stj16 grew vigorously at 25?C?30?C,for stj16,it produced the highest number of conidia at 30?C compared with other temperature,it explained the environment condition of the field for benefit the breaking of the disease,namely the pathogen can break fast and cause severe damage in the high humid condition and rainy season in the summer.