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Molecular mapping of an apical branching gene of cultivated sunflower (Helianthus annuus L.)

Rojas-Barros, Pilar, Hu, Jinguo, Jan, C. C.
Theoretical and applied genetics 2008 v.117 no.1 pp. 19-28
Helianthus annuus, bovine serum albumin, branching, chromosome mapping, crossing, cytoplasmic male sterility, genes, genetic distance, hybrids, linkage groups, loci, marker-assisted selection, molecular cloning, pollination, pollinators, polymerase chain reaction, restriction fragment length polymorphism, seeds
Commercial hybrids of cultivated sunflower (Helianthus annuus L.) are obtained by crossing a cytoplasmic male sterile line (A-line) with a restorer pollinator (R-line). The incorporation of a recessive branching trait to extend the pollination period of R-lines during hybrid seed production is laborious and time-consuming. By using target region polymorphism (TRAP) and bulked segregant analysis (BSA), we identified 15 TRAP markers linked to the b ₁ (branching) locus in a population of 229 F₂ plants derived from a cross between nonbranched (HA 234) and branched (RHA 271) lines. TBr4-720 and TBr8-555 markers were linked to the b ₁ gene in the coupling phase at 0.5 cM (0.004 recombination frequency). The Tbr20-297 and Tbr20-494 markers flanked the b ₁ locus in the repulsion phase at genetic distances of 7.5 and 2.5 cM, respectively. Tbr19-395, also in the repulsion phase, mapped at 3.8 cM from the b ₁ locus and on the opposite side of the marker Tbr20-297. The 8A1 and 15B3 restriction fragment length polymorphic (RFLP) markers of linkage group (LG) 16 of the RHA 271 x HA 234 cultivated sunflower map anchored the b ₁ LG onto the RFLP map. Polymerase chain reaction (PCR)-based markers tightly linked to the recessive b ₁ gene have been developed. Their identification and the incorporation of the LG containing the b ₁ locus onto an RFLP map will be useful for marker-assisted selection (MAS) in breeding programs and provide the bases for map-based cloning of this gene.