Detection and molecular characterization of Polymyxa betae, transmitting agent of sugar beet rhizomania disease, in Iran

The plasmodiophorid Polymyxa betae is considered as the only natural transmitting agent of Beet necrotic yellow vein virus (BNYVV), the most devastating agent of sugar beet fields throughout the world. To evaluate for the first time the genetic diversity of P betae isolated from different autumn and spring sugar beet fields, and also to detect the presence of virus in these isolates, susceptible sugar beet plants (cv. Regina) were grown in soil samples collected from 10 different regions of Iran. P betae detection was carried out using root microscopic observations, DAS-ELISA, and PCR-based methods. Results showed the presence of plasmodiophorids in all soil samples. Complementary assays also revealed the presence of viruses in soil samples collected from Khorasan Razavi, Fars, Hamadan and Kermanshah regions. The genetic diversity was evaluated through comparing glutathione-S-transferase nucleotide sequences amplified by PCR with the Internal Transcribed Spacers region. Results showed no significant differences in nucleotide sequences between virus-bearing and virus-free isolates of P betae.