Theoretical expectation for population sizes required for detection of HF events at various expected HF frequencies.

<p>Sample sizes required were calculated for each expected HF frequency to ensure to detect HF events at probability levels of 0.90, 0.95 and 0.99, respectively.</p

Probability of a marker confirming a hetero-fertility event.

<p>*The number of markers that are expected to be polymorphic was estimated using the averaged polymorphism rate (36.3%) as revealed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0016101#pone.0016101-Yan1" target="_blank">[16]</a> using the same SNP chip for genotyping.</p

Detection of hetero-fertilization event contributed by maternal gametophyte in three-way cross populations.

<p>An HF plant in HP9 was detected as shown by the arrow. E: endosperm, L: leaf; A, B and C: three alleles derived from three different parents in the cross model (A×B)×C.</p

A diagram showing the probability for an HF event to be detected by using one polymorphic marker.

<p>For a given HF event and a given segregating marker locus within a population, two independent sperm cells derived from two different pollen grains, represented by H (triangle) and h (circle), respectively, can be only detected, with the probability of 50% (A), when the two pollen grains carry different alleles. However, when the two pollen grains carry the same allele (either H or h), the HF event is not detectable. The chance for the two pollen grains to carry the same H (B) or h (C) is 25%.</p

Hetero-fertilization event detected in F₂ populations.

<p>Genotype difference between endosperm DNA (E) and embryo DNA (L) can be revealed by one polymorphic SSR marker as shown by the arrow.</p

Table_1_Dissecting the Genetic Basis Underlying Combining Ability of Plant Height Related Traits in Maize.DOCX

<p>Maize plant height related traits including plant height, ear height, and internode number are tightly linked with biomass, planting density, and grain yield in the field. Previous studies have focused on understanding the genetic basis of plant architecture traits per se, but the genetic basis of combining ability remains poorly understood. In this study, 328 recombinant inbred lines were inter-group crossed with two testers to produce 656 hybrids using the North Carolina II mating design. Both of the parental lines and hybrids were evaluated in two summer maize-growing regions of China in 2015 and 2016. QTL mapping highlighted that 7 out of 16 QTL detected for RILs per se could be simultaneously detected for general combining ability (GCA) effects, suggesting that GCA effects and the traits were genetically controlled by different sets of loci. Among the 35 QTL identified for hybrid performance, 57.1% and 28.5% QTL overlapped with additive/GCA and non-additive/SCA effects, suggesting that the small percentage of hybrid variance due to SCA effects in our design. Two QTL hotspots, located on chromosomes 5 and 10 and including the qPH5-1 and qPH10 loci, were validated for plant height related traits by Ye478 derivatives. Notably, the qPH5-1 locus could simultaneously affect the RILs per se and GCA effects while the qPH10, a major QTL (PVE > 10%) with pleiotropic effects, only affected the GCA effects. These results provide evidence that more attention should be focused on loci that influence combining ability directly in maize hybrid breeding.</p

Analysis of chromosome segments introgression of <i>O2</i> based on SSR markers mapping to bin7.01.

<p>The positions of SSR markers are based on a map from IBM2 2008 Neighbors 7. The red fragments (A) are of recurrent parent origin, blue fragments (B) are of donor origin, and gray fragments (U) represent markers that have no polymorphism between the two parents, and have no information for that genotype.</p

Image_3_Dissecting the Genetic Basis Underlying Combining Ability of Plant Height Related Traits in Maize.TIF

<p>Maize plant height related traits including plant height, ear height, and internode number are tightly linked with biomass, planting density, and grain yield in the field. Previous studies have focused on understanding the genetic basis of plant architecture traits per se, but the genetic basis of combining ability remains poorly understood. In this study, 328 recombinant inbred lines were inter-group crossed with two testers to produce 656 hybrids using the North Carolina II mating design. Both of the parental lines and hybrids were evaluated in two summer maize-growing regions of China in 2015 and 2016. QTL mapping highlighted that 7 out of 16 QTL detected for RILs per se could be simultaneously detected for general combining ability (GCA) effects, suggesting that GCA effects and the traits were genetically controlled by different sets of loci. Among the 35 QTL identified for hybrid performance, 57.1% and 28.5% QTL overlapped with additive/GCA and non-additive/SCA effects, suggesting that the small percentage of hybrid variance due to SCA effects in our design. Two QTL hotspots, located on chromosomes 5 and 10 and including the qPH5-1 and qPH10 loci, were validated for plant height related traits by Ye478 derivatives. Notably, the qPH5-1 locus could simultaneously affect the RILs per se and GCA effects while the qPH10, a major QTL (PVE > 10%) with pleiotropic effects, only affected the GCA effects. These results provide evidence that more attention should be focused on loci that influence combining ability directly in maize hybrid breeding.</p

Maize kernel zein accumulation of liao2345/<i>o2</i>-1, liao2345/<i>o2</i>-2, liao2345, and CA339 in mature seeds, detected by SDS/PAGE.

<p>Total zein loaded in each lane is equal to 1 mg of mature seed endosperm, and the relative molecular weights of proteins are marked at the right side, the unit is kDa.</p

Hetero-fertilization frequencies detected in four three-way cross populations.

<p>Note: The two pollination models for three-way crosses are (A×B)×C and A×(B×C). For consistency, the genotypes of SSR allele combination in endosperm (E) and leaf (L) are shown using the same symbol with the pollination model A, B and C.</p