The mRNA sequence polymorphisms of flowering key genes in bolting sensitive or tolerant sugar beet genotypes

One of the most important characteristics of sugar beet planting in temperate climates is the tolerance against early bolting. Understanding the genetic control of sugar beet flowering can help to develop the bolting-tolerant cultivars. In this study, the transcript sequences of 2 VIN3 copies, frigida, VRN1, EMF2, BvFT1, and BTC1 genes in 4 bolting tolerant and sensitive sugar beet genotypes were evaluated. Leaf samples were taken from plants in 2 growing stages, before and during cold exposure. The amplified fragments of both tolerant and sensitive genotypes were similar in length and the comparison of their transcript sequence showed polymorphism. In overall, 18 mutations comprising 1 mutation in frigida sequence, 14 single nucleotide polymorphisms (SNPs) in 2 copies of BvVIN3 sequence, 2 SNPs in BvFT1 sequence, and 1 insertion/deletion mutation for BTC1 were characterized. The last one caused a frameshift in the encoded protein. Despite the key role of the above mentioned genes, results showed that SNPs identified in this study were not associated with bolting tolerance or sensitivity. There may be differences in the expression levels of these proteins, which necessitates further exploration.