Identification of informative markers associated with virulence trait of Cytospora chrysosperma (Pers.) Fr. isolates on walnut seedlings using RAPD and ISSR markers

This study was conducted to determine the relationship of RAPD and ISSR markers with virulence of 58 isolates of Cytospora chrysosperma (Pers.) Fr. on walnut seedlings using stepwise regression. The results of RAPD and ISSR tests showed that 10 out of 20 RAPD primers and 12 out of 20 ISSR primers had significant amount of appearance, polymorphism and repeatability among different isolates. Ten and twelve selected primers showed a high amount of polymorphic respectively 94.7% and 95.8% in different isolates. For further analysis the data of virulence trait, was considered as dependent variable and molecular data (0,1) were entered as independent variables in the regression models and the bands with high R2 in regression models were selected for further discussion. Five RAPD markers were related to virulence and totally explained 43.7% of variation of the trait. Out of them two markers showed positive relation and 3 of them showed negative relation with the virulence. The highest percentage of explained variance belonged to marker A7=1900 bp (R2=18.2%) and lowest was due to marker OP13=400 bp (R2=4.8%). Also five ISSR markers were related to virulence and totally explained 39% of variation of the trait. Out of them 3 markers showed positive relation and two of them showed negative relation with the virulence. The highest percentage of explained variance belonged to marker UBC864=350 bp (R2=11.6%) and lowest was due to marker UBC880=740 bp (R2=5.4%). Indentified markers could be used for marker assisted selection (MAS) and therefore to identify isolates.