The determination of Beet virus Q in Turkey sugar beet grown areas and molecular characterization of soil-borne viruses transmitted by Polymyxa betae

It is known that Beet necrotic yellow vein virus (BNYVV), Beet soil-borne virus (BSBV) and Beet virus Q (BVQ) are the most common soil-borne viral agents in sugar beet production areas. These viruses are transmitted by the protozoan vector Polymyxa betae. In this study, a total of 103 soil samples collected from 31 provinces of Turkiye belonging to sugar beet fields were used. It is known that 82 of them were infested with BNYVV and/or BSBV, and 21 of them were only infested with vector P. betae. Following the bait plant test, 89.3% of the soil samples examined by RT-PCR studies were found to be infested with BVQ. In addition, the host range of the two BVQ isolates was also examined. Systemic infection of BVQ on Beta macrocarpa, Nicotiana benthamiana, N. rustica, Patellifolia patellaris and Spinacia oleracea after mecahanical sap-inoculation was first demonstrated by RT-PCR and sequence analysis studies. BVQ was first reported by these results in Turkiye. In this study, nucleotide (nt) and amino acid (aa) sequences of coat protein (CP) gene regions of 15 BVQ, 16 BNYVV and 10 BSBV isolates selected according to their geographical origin were obtained. It was determined that 15 BVQ isolates showed the highest aa similarity (98.80%) with FP71 isolate from France. Of the ten BSBV isolates examined in the study, nine had 100% similarity among them in terms of aa sequence, while the YZT-355S isolate exhibited differences from the other Turkish and world isolates in aa positions 92, 121 and 122. Nine BSBV isolates were found to be 100% similar to pBSBV-cp061027-1 isolate from China in terms of aa sequence. It was determined that YZT-355S isolate showed the highest genetic similarity (98.17%) with BSBV isolates belonging to China, Poland and Turkey. When the CP region-aa sequences of BNYVV isolates were examined, it was determined that the CPs of 14 isolates were A-type character, whereas those of IGR-9 and ERC-52 isolates were A (P)-type. In addition, the gene regions (P25, P26, P31) belonging to different RNA segments of BNYVV isolates with A (P)-type CP were also examined. As a result, it was found that these A (P)-type BNYVV isolates were highly aggressive and able to infect different sugar beet genotypes carrying various resistance genes (Rz1, Rz1+Rz2 and Rz1+C48+minör genes). In addition, the reactions of different KNY-359 isolates in test plants were studied.