RFLP MAPPING OF 5 MAJOR GENES AND 8 QUANTITATIVE TRAIT LOCI CONTROLLING FLOWERING TIME IN A WINTERXSPRING BARLEY (HORDEUM-VULGARE L) CROSS

A genetic map of 92 RFLP loci and two storage protein loci was made us ing 94 doubled-haploid lines from a cross between the winter barley va riety Igri and the spring variety Triumph. The markers were combined w ith data from two field experiments (one spring sown and one autumn (f all) sown) and a glasshouse experiment to locate a total of 13 genes ( five major genes and eight quantitative trait loci (QTL)) controlling flowering time. Two photoperiod response genes were found; Ppd-H1 on c hromosome 2(2H)S regulated flowering time under long days, while Ppd-H 2 on chromosome 5(1H)L was detected only under short days. In the fiel d experiments Ppd-HI strongly affected flowering time from spring and autumn sowings, while Ppd-H2 was detected only in the autumn sowing. T he glasshouse experiment also located two vernalization response genes , probably Sh and Sh(2), on chromosomes 4(4H)L and 7(5H)L, respectivel y. The vernalization response genes had little effect on flowering tim e in the field. Variation in flowering time was also affected by nine additional genes, whose effects were nor specifically dependent on pho toperiod or vernalization. One was the dense dwarfing gene on chromoso me 3(3H)L. The remaining eight were QTLs of smaller effect. One was lo cated on chromosome 2(2H), one on 3(3H), one on 4(4H), one on 7(5H), t wo on 6(6H), and two on 1(7H). Model fitting showed that the 13 putati ve genes, and their interactions, could account for ail the observed g enetical variation from both spring and autumn sowings, giving a compl ete model for the control of flowering time in this cross.