Search

Combining ability is crucial for parent selection in crop hybrid breeding. Many studies have attempted to provide reliable and quick methods to identify genome regions in parental lines correlating with improved hybrid performance. The local haplotype patterns surrounding densely spaced DNA markers include a large amount of genetic information, and analysis of the relationships between haplotypes and hybrid performance can provide insight into the underlying genome regions which might contribute to enhancing combining ability. Here, we generated 24,403 single-copy, genome-wide SNP loci and calculated the general combining ability (GCA) of 950 hybrids from a diverse panel of 475 pollinators of spring-type canola inbred lines crossed with two testers for days to flowering (DTF) and seed glucosinolate content (GSL). We performed a genome-wide analysis of the haplotypes and detected eight and seven haplotype regions that were significantly associated with the GCA values for DTF and seed GSL, respectively. Additionally, two haplotype blocks containing orthologs of flowering time genes FLOWERING LOCUS T (FT) and FLOWERING LOCUS C (FLC) on chromosome A02 showed additive epistatic interactions influencing flowering time. Moreover, two homoeologous haplotype regions on chromosomes A02 and C02 corresponded to major quantitative trait loci (QTL) for GSL which showed additive effects related to reduction of seed GSL in F1 hybrids. Our study showed that haplotype analysis has the potential to substantially improve the efficiency of hybrid breeding programs.

Chlorophyll levels provide important information about plant growth and physiological plasticity in response to changing environments. The stay-green gene NON-YELLOWING 1 (NYE1) is believed to regulate chlorophyll degradation during senescence, concomitantly affecting the disassembly of the light-harvesting complex and hence indirectly influencing photosynthesis. We identified Brassica napus accessions carrying an NYE1 deletion associated with increased chlorophyll content, and with upregulated expression of light-harvesting complex and photosynthetic reaction center (PSI and PSII) genes. Comparative analysis of the seed oil content of accessions with related genetic backgrounds revealed that the B. napus NYE1 gene deletion (bnnye1) affected oil accumulation, and linkage disequilibrium signatures suggested that the locus has been subject to artificial selection by breeding in oilseed B. napus forms. Comparative analysis of haplotype diversity groups (haplogroups) between three different ecotypes of the allopolyploid B. napus and its A-subgenome diploid progenitor, Brassica rapa, indicated that introgression of the bnnye1 deletion from Asian B. rapa into winter-type B. napus may have simultaneously improved its adaptation to cooler environments experienced by autumn-sown rapeseed.

Mice lacking functional Cav1.3 L-type Ca2+-channels show sinoatrial node dysfunction and are congenitally deaf. Here we investigated the functional consequences of a homozygote mutation (insertion of an amino acid residue in a pore-forming S6-helix) in the alpha1-subunit encoding the CACNA1D gene which causes bradycardia and deafness in humans.We expressed human wildtype (WT) and mutant channel complexes (MUT) in tsA-201 cells (with alpha2delta and beta3-subunits) and recorded ON-gating (Qon) and ionic Ca2+-currents (ICa) using the whole-cell patch-clamp technique. Full length WT and MUT channel alpha1 subunit proteins were expressed at equal levels in tsA-201 membranes. In contrast to WT, MUT channels did not conduct significant ICa, but gave clear rise to Qon. WT and MUT Qon exhibited a typical nonlinear voltage-dependence of activation. Under identical experimental conditions (block of ICa by replacing Ca2+ with Mg2+ and addition of La3+ and Cd2+ in the recording solution) the half maximal activation voltage (Vh) of MUT Qon was significantly shifted by 16.2±2.8 mV (n=6-8, p