میزبانان جدید Polymyxa betae از ایران

Polymyxa betae was first described as the parasite of sugarbeet root by Keskin in 1964. However, it is its role in the survival and transmission of Beet necrotic yellow vein virus which makes P. betae economically important. Weed hosts may play a more important role than sugar beet and spinach in the spread and persistence of P. betae. The reported weed hosts of P. betae include Amaranthus retrosflexus, Atriplex patula, Chenopodium album, Portulaca oleracea, P. grandiflora, Papaver argemone, Silene alba, S. vulgaris, S. noctiflora and Stellaria graminea. In the present work, we examined weeds of sugar beet fields in Lorestan and Fars provinces for the presence of P. betae. Sampling of roots was carried out in 2012. The weeds sampled included Amaranthus blitoides, A. retrosflexus, Asperugo procumbens, Chenopodium album, Cirsium arvense, Conringia orientalis, Convolvulus arvensis, Heliotropium europaeum, Hibiscus trionum, Malva sylvestris, Melilotus officinalis, Portulaca oleracea, Raphanus raphanistrum, Setaria viridis, Sonchus oleraceus, Spergula arvensis, Tragopogon graminifolius and Xanthium strumarium. DNA was extracted  from the roots by Guanidin method (MacKenzie et al., 1997) and subjected to amplification by conventional PCR using P.betae specific primers. P. betae was detected in A. retroflexus, C. album, P. oleracea, R. raphanistrum and S. arvensis. R. raphanistrum and S. arvensis as the hosts of P. betae are new world records. These weeds may contribute to the survival of P. betae and BNYVV while rotating sugar beet with other crops.