Bolting tendency in sugar beet is a complex trait has been shown to be controlled by various environmental cues, including prolonged periods of cold temperatures over winter (vernalization) and photoperiod, and multiple genetic factors. Three loci (B, B2 and B4) which trigger bolting in the absence of vernalization were identified and genetically mapped in beet. B4 is linked to the B locus and promotes annual bolting independently of B. Here, genetic analysis of a large segregated F2 population derived from a cross between a biennial sugar beet and an annual beet accession phenotyped for bolting tendency under three environmental conditions, i.e., long day after vernalization, long day without vernalization and shortening daylength revealed the presence of a major gene which is linked to the gene B and suppresses bolting under unfavorable daylength (shortening daylength) and negatively affects bolting time.