Mapping of QTL for intermedium spike on barley chromosome 4H using EST-based markers

Abstract

The lateral spikelets of two-rowed barley are reduced in size and sterile, but in six-rowed barley all three spikelets are fully fertile. The trait is largely controlled by alleles at the vrs1 locus on chromosome arm 2HL, as modified by the allele present at the I locus on chromosome arm 4HS. Molecular markers were developed to saturate the 4HS region by exploiting expressed sequence-tags, either previously mapped in barley to this region, or present in the syntenic region of rice chromosome 3. Collinearity between rice and barley was strong in the 4.8 cM interval BJ468164-AV933435 and the 10 cM interval AV942364-BJ455560. A major QTL for lateral spikelet fertility (the I locus) explained 44% of phenotypic variance, and was located in the interval CB873567-BJ473916. The genotyping of near-isogenic lines for I placed the locus in a region between CB873567 and EBmac635, and therefore the most likely position of the I locus was proximal to CB873567 in a 5.3 cM interval between CB873567-BJ473916.

Identification of Rf9, a Gene Contributing to the Genetic Complexity of Fertility Restoration in Hybrid Wheat

“…To detect the QTL controlling seed set and number of sterile spikelets per spike in BC 1 populations, composite interval mapping with a 5-cM window and a maximum of 10 marker cofactors per model was carried out using the Windows QTL Cartographer version 2.5 (Wang et al, 2012). Tests were performed at 1-cM intervals, and cofactors were selected by the forward-backward stepwise regression Model 6 (Shahinnia et al, 2009;Wang et al, 2012). Genome-wide, trait-specific threshold values (α = 0.05) of the likelihood ratio test statistic for declaring the presence of a significant QTL was determined by 2,000 permutations (Churchill and Doerge, 1994).…”