Genetic Variation Among Four Local Isolates of Oidium neolycopersici, one of the Causal Agents of the Powdery Mildew Disease of tomato using Inter Simple Sequence Repeats (ISSR) Technique

Abstract

Oidium neolycopersici is one of the tomato powdery mildew pathogens in greenhouses. This study aimed to determine the genetic relatedness and pathogenicity of four local isolates (M8, M10, G12, and R12) of O. neolycopersici using the Inter Simple Sequence Repeats (ISSR) technique. The DNA of the isolates was amplified using 23 ISSR primers. The results obtained showed that there was no significant variation in pathogenicity among the tested isolates. Only 11 primers gave polymorphism among the studied isolates, yielding a total of 191 bands; 58 of which were polymorphic, and the polymorphism rate was 31%. The number of polymorphic bands ranged between 1 band with the primer A8 to16 bands with the primer E11, with an average of 5.2 bands per primer. Genetic divergence values were low in general, ranging between 0.05 and 0.26, which means high genetic relatedness between the isolates. The phylogenetic tree was divided into two main clusters: the first included the two isolates M10 (Alkhrab region) and M8 (Alademah region), which had a 95% genetic similarity. The second included G12 and R12 isolates with a high degree of relatedness (92%), but lower than the previous ones, even though the two isolates were collected from the same region (Matn Abu Raya). The results revealed that ISSR technique was effective in detecting diversity and genetic relatedness among O. neolycopersici isolates.

Keywords:

Oidium neolycopersici, powdery mildew, genetic variation, tomato, ISSR.