Identification of Resistant Sugar Beet (Beta vulgaris L.) Genotypes against Beet Curly Top Disease

The Severe strain of Beet Curly Top Virus (BCTV-Svr) and Beet Curly Top Iran Virus (BCTIV) are considered as the main causal agents of sugar beet curly top disease in Iran and mixed infections of BCTV-Svr and BCTIV usually occur in nature. As the use of resistant cultivars is the safer and stable tool for management of the disease, the objective of current work was to identify sugar beet genotypes resistant to both agents. To this end, the reaction of thirty-eight sugar beet genotypes to infection by each of BCTV-Svr and BCTIV was separately evaluated using their infectious clones under the greenhouse condition. Incubation period, recovery, and disease severity index were considered for selection of resistant genotypes. As a result, ten and seven sugar beet genotypes resistant to, respectively, BCTV-Svr and BCTIV were selected. To evaluate the resistant genotypes, the experiments were repeated under greenhouse condition. In the field experiment with natural infection of viruses, the resistant genotypes were assessed and six sugar beet genotypes (S1 91019, S1 91022, S1 91023, S1 91028, S1 91029, and S1-91041) resistant to BCTV-Svr and BCTIV were identified; which could be used in future breeding programs.