This study was conducted to identify the quantitative trait loci (QTL) associated with grain yield and its related traits by analysis of 122 doubled haploid population derived from a cross between Korean wheat cultivars carried different yield potential. DH population was evaluated in replicated field trials in 2011/2012 and 2012/2013 at upland and paddy conditions in Iksan, Korea. Grain yield and its related traits, including days to heading and maturity, culm and spike length, spike number per m 2 , kernel number per spike, and thousand kernel weight, were investigated. A genetic map was constructed with 140 microsatellite marker loci and a total of nine QTLs were identified on eight chromosomes for grain yield and its related traits. The three QTLs, Xgpw2206, Xgwm247, and Xwmc471, were detected on chromosomes 2A, 3A, and 3B, and explained 10.1-22.8 % of phenotypic variation for grain yield. Among these QTLs, Xgpw2206 and Xgwm247 explained 10.7-37.9 % of phenotypic variation for days to heading and maturity, spike length, spike number per m 2 , and kernel number per spike. Other six QTLs on chromosomes 2D, 4A, 5A, 6A, and 7A accounted for 11.4-39.9 % of phenotypic variation for culm and spike length, spike number per m 2 , and thousand kernel weight. Those three QTLs for grain yield were applied to validate relationship between genotypes of QTL and 25 Korean wheat cultivars. Korean wheat cultivars carried hha genotypes based on the order of those three QTLs, showed higher GY (664.4 kg/ 10a) than genotype bha (494.2 kg/10a). Those three QTLs could be used in marker-assisted selection to improve grain yield and its related traits in Korean wheat breeding programs.

The allelic variations at the Rht-1, Vrn-1 and Ppd-1 of 410 Korean wheat cultivars, including 111 Korean experimental lines, 238 Korean landraces and 61 North Korean collections, were investigated to provide the information of plant height and heading date and to elucidate the relationship between those traits and allelic variation of these genes because earliness is major consideration in Korean wheat production. All Korean wheats displayed vrn-A1 and Ppd-A1b alleles, while Rht-B1a, Rht-D1a, vrn-B1, Vrn-D1, Ppd-B1b and Ppd-D1a alleles were also predominantly found. Most Korean wheats carried both Rht-B1a and Rht-D1a alleles, both vrn-B1 and Vrn-D1 alleles, or both Ppd-B1b and Ppd-D1a alleles. The Rht-B1a, vrn-D1, Ppd-B1b and Ppd-D1b alleles were found to exhibit longer culm and spike length than their counterpart alleles. The Rht-B1a allele also showed longer spike length than Rht-B1b. Vrn-B1b and vrn-D1 alleles exhibited longer days to heading date than their counterpart alleles at the Vrn-B1 and Vrn-D1 loci. Lines carrying both Rht-B1b and Rht-D1b alleles displayed shorter culm and longer spike length and days to heading date than any other combination of alleles at the Rht-B1 and Rht-D1 loci. In contrast, lines carrying both Ppd-B1b and Ppd-D1b alleles exhibited longer culm and spike length than any other combination of alleles at the Ppd-B1 and Ppd-D1 loci.

This is anABSTRACT Pre-harvest sprouting (PHS) of wheat reduces grain yield and has deleterious effects on wheat flour quality. PHS resistance is strongly associated with grain color and seed dormancy. Resistance to PHS is a priority of wheat breeding program. We have studied a population of 122 Doubled Haploid (DH) lines from the cross between two cultivars, 'Keumkang' and 'Olgeuru', in order to detect QTLs correlated with PHS resistance. PHS was evaluated using mist spray in the humid chamber (PHS-MS), and the germination index (GI) was determined for two years. The variety 'Keumkang' has white grains and higher percentage of PHS rate (30.2%), while 'Olgeuru' has red grains and lower PHS rate (2.8%). There was significant difference in grain color according to the GI. PHS-MS was positively correlated with GI (r = 0.732, P < 0.001). Two molecular markers, Xbarc12 and Xgwm3, were found correlated with PHS resistance and GI. These markers were mapped on chromosomes 3A and 3D with LOD scores of 4.95 and 4.02, respectively. Xbarc12 explained the highest amount of phenotypic variation (R 2 ) which is 11.99% in GI and 27.25% in PHS. Xgwm3 explained 9.10% of phenotypic variation in GI. The respective value of PHS-MS and GI in Korean wheat cultivars ranged from 1.37% to 86.75% and from 0.03 to 0.73. This study provides useful information for marker-assisted wheat breeding for PHS resistance improvement in Korea.

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