IDENTIFICATION OF RFLP MARKERS CLOSELY LINKED TO THE BOLTING GENE-B AND THEIR SIGNIFICANCE FOR THE STUDY OF THE ANNUAL HABIT IN BEETS (BETA-VULGARIS L)

The annual habit in beet is due to complete or partial absence of the vernalization requirement and can cause severe problems in the beet crop. The absolute vernalization requirement in beet is controlled by a major gene B (bolting), known to be linked to the gene R (red hypocotyl color), in linkage group I. Segregation for the B and R genes was studied in several beet progenies. Penetrance of the annual habit in Bb genotypes was affected by both environmental and genetic factors. The precise location in linkage group I of the major gene B was found by restriction fragment length polymorphism (RFLP) analysis in a back-cross progeny exhibiting partial penetrance of the annual habit. The linkage value between B and R was in good accordance with previous estimations. Use of the closest RFLP marker (pKP591: 3.8 recombination units) allowed us to estimate the penetrance of the annual habit in this back-cross as 0.62. Evidence of pseudo-compatibility was found in the wild coastal beet (Beta vulgaris ssp maritima) used as the mother plant of the back-cross: the selfing rate was estimated as 7%.