Seyed Bagher Mahmoudi - Sugar Beet Seed Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
Maryam Saffarian Abbaszadeh - Clemson University, South Carolina, USA.
Saeed Abbasi - Department of Plant Protection, College of Agriculture, Razi University, Kermanshah, Iran.
Reza Farrokhinejad - Department of Plant Protection, College of Agriculture, Shahid Chamran Universty of Ahvaz, Ahvaz, Iran.

Cercospora leaf spot caused by Cercospora beticola has a great negative impact on yield and quality of sugar beet. In the present study, pathogenic and genotypic variation of ۲۴ C. beticola isolates collected from different regions of Iran were studied using RFLP of the Internal Transcribed Spacer (ITS-RFLP), and Random Amplified Polymorphic DNA (RAPD-PCR). Pathogenic variability and genotype × isolate interaction were evaluated in greenhouse experiments on five sugar beet cultivars (FD۰۰۱۸, HM۱۸۳۶, Puma, Eudora and Monatuna). All of the ۲۴ isolates tested were found to be pathogenic on the cultivars with significant variation in disease severity. Results of RAPD analysis showed wide DNA polymorphism among the Iranian C. beticola isolates. Restriction pattern of the internal transcribed spacer of rDNA (ITS۱-۵.۸-ITS۴) was studied using three restriction endonucleases: EcoR۱, Taq۱, and Busr۱. The length of undigested DNA fragment of all isolates was estimated to be ۵۰۰bp without rDNA polymorphism after digestion with EcoR۱ (۲۸۰, ۲۷۰ bp), Taq۱ (۳۳۰ bp) and Busr۱ (۲۴۰, ۲۲۰, ۹۰ bp). RAPD and ITS-RFLP markers showed the highest level of genetic diversity which confirms the variation in C. beticola detection.

Cercospora beticola, genotype × isolate interaction, Pathogenicity, RAPD fingerprinting, بیماری زایی, انگشت نگاری به کمک RAPD, تعامل جدایه در ژنوتیپ, Cercospora beticola