Introgression Breeding Programs Research Articles

Genome-Wide Syntenic and Evolutionary Analysis of 30 Key Genes Found in Ten Oryza Species

Rice is a vital staple food crop worldwide, providing nutrition and sustenance to a significant portion of the global population. The genetic diversity of cultivated rice species has been significantly reduced during domestication, resulting in the loss of favorable alleles. To overcome this limitation, wild rice species have been used in introgression breeding programs to introduce beneficial alleles. In this study, we performed syntenic and phylogenetic analyses for 10 Oryza species, comprising both cultivar and wild species. Pairwise syntenic analysis revealed 3885 synteny blocks containing 1,023,342 gene pairs among 10 species. O. nivara contained the most blocks that were syntenous with the other nine species. In total, 425 paralogous and orthologous genes were identified for 30 key genes involved in rice breeding. His1 (43), GS3 (28), and qSW5/GW5 (27) had the most paralogous and orthologous genes. For GS3 and qSW5/GW5, two gene transfer events were detected. These findings have implications for rice breeding strategies, particularly with respect to gene pyramiding and introgression breeding programs. This research will contribute to the development of elite cultivars with improved quality and yield to meet the growing global demand for high-quality rice.

Precise Identification of Chromosome Constitution and Rearrangements in Wheat-Thinopyrum intermedium Derivatives by ND-FISH and Oligo-FISH Painting.

Thinopyrum intermedium possesses many desirable agronomic traits that make it a valuable genetic source for wheat improvement. The precise identification of individual chromosomes of allohexaploid Th. intermedium is a challenge due to its three sub-genomic constitutions with complex evolutionary ancestries. The non-denaturing fluorescent in situ hybridization (ND-FISH) using tandem-repeat oligos, including Oligo-B11 and Oligo-pDb12H, effectively distinguished the St, J and JS genomes, while Oligo-FISH painting, based on seven oligonucleotide pools derived from collinear regions between barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), was able to identify each linkage group of the Th. intermedium chromosomes. We subsequently established the first karyotype of Th. intermedium with individual chromosome recognition using sequential ND-FISH and Oligo-FISH painting. The chromosome constitutions of 14 wheat–Th. intermedium partial amphiploids and addition lines were characterized. Distinct intergenomic chromosome rearrangements were revealed among Th. intermedium chromosomes in these amphiploids and addition lines. The precisely defined karyotypes of these wheat–Th. intermedium derived lines may be helpful for further study on chromosome evolution, chromatin introgression and wheat breeding programs.

Searching for Abiotic Tolerant and Biotic Stress Resistant Wild Lentils for Introgression Breeding Through Predictive Characterization.

Crop wild relatives are species related to cultivated plants, whose populations have evolved in natural conditions and confer them valuable adaptive genetic diversity, that can be used in introgression breeding programs. Targeting four wild lentil taxa in Europe, we applied the predictive characterization approach through the filtering method to identify populations potentially tolerant to drought, salinity, and waterlogging. In parallel, the calibration method was applied to select wild populations potentially resistant to lentil rust and broomrape, using, respectively, 351 and 204 accessions evaluated for these diseases. An ecogeographic land characterization map was used to incorporate potential genetic diversity of adaptive value. We identified 13, 1, 21, and 30 populations potentially tolerant to drought, soil salinity, waterlogging, or resistance to rust, respectively. The models targeting broomrape resistance did not adjust well and thus, we were not able to select any population regarding this trait. The systematic use of predictive characterization techniques may boost the efficiency of introgression breeding programs by increasing the chances of collecting the most appropriate populations for the desired traits. However, these populations must still be experimentally tested to confirm the predictions.

The hybrid lethality of interspecific F1 hybrids of Nicotiana: a clue to understanding hybrid inviability-a major obstacle to wide hybridization and introgression breeding of plants.

Reproductive isolation poses a major obstacle to wide hybridization and introgression breeding of plants. Hybrid inviability in the postzygotic isolation barrier inevitably reduces hybrid fitness, consequently causing hindrances in the establishment of novel genotypes from the hybrids among genetically divergent parents. The idea that the plant immune system is involved in the hybrid problem is applicable to the intra- and/or interspecific hybrids of many different taxa. The lethality characteristics and expression profile of genes associated with the hypersensitive response of the hybrids, along with the suppression of causative genes, support the deleterious epistatic interaction of parental NB-LRR protein genes, resulting in aberrant hyper-immunity reactions in the hybrid. Moreover, the cellular, physiological, and biochemical reactions observed in hybrid cells also corroborate this hypothesis. However, the difference in genetic backgrounds of the respective hybrids may contribute to variations in lethality phenotypes among the parental species combinations. The mixed state in parental components of the chaperone complex (HSP90-SGT1-RAR1) in the hybrid may also affect the hybrid inviability. This review article discusses the facts and hypothesis regarding hybrid inviability, alongside the findings of studies on the hybrid lethality of interspecific hybrids of the genus Nicotiana. A possible solution for averting the hybrid problem has also been scrutinized with the aim of improving the wide hybridization and introgression breeding program in plants.

Marker-Assisted Introgression and Stacking of Major QTLs Controlling Grain Number (Gn1a) and Number of Primary Branching (WFP) to NERICA Cultivars.

The era of the green revolution has significantly improved rice yield productivity. However, with the growing population and decreasing arable land, rice scientists must find new ways to improve rice productivity. Although hundreds of rice yield-related QTLs were already mapped and some of them were cloned, only a few were utilized for actual systematic introgression breeding programs. In this study, the major yield QTLs Grain Number 1a (Gn1a) and Wealthy Farmer’s Panicle (WFP) were introgressed and stacked in selected NERICA cultivars by marker-assisted backcross breeding (MABB). The DNA markers RM3360, RM3452, and RM5493 were used for foreground selection. At BC3F4 and BC3F5 generation, a combination of marker-assisted selection and phenotypic evaluation were carried out to select lines with target alleles and traits. Further, genotyping-by-sequencing (GBS) was conducted to validate the introgression and determine the recurrent parent genome recovery (RPGR) of the selected lines. The Gn1a and/or WFP introgression lines showed significantly higher numbers of spikelets per panicle and primary branching compared to the recurrent parents. In addition, lines with Gn1a and/or WFP alleles were comparatively similar to the recurrent parents (RP) in most yield-related traits. This study demonstrates the success of utilizing yield QTLs and marker-assisted selection to develop and improve rice cultivars.

Potential Short-Term Memory Induction as a Promising Method for Increasing Drought Tolerance in Sweetpotato Crop Wild Relatives [Ipomoea series Batatas (Choisy) D. F. Austin

Crop wild relatives of sweetpotato [Ipomoea series Batatas (Choisy) D. F. Austin] are a group of species with potential for use in crop improvement programs seeking to breed for drought tolerance. Stress memory in this group could enhance these species’ physiological response to drought, though no studies have yet been conducted in this area. In this pot experiment, drought tolerance, determined using secondary traits, was tested in 59 sweetpotato crop wild relative accessions using potential short-term memory induction. For this purpose, accessions were subjected to two treatments, i) non-priming: full irrigation (up to field capacity, 0.32 w/w) from transplanting to harvest and ii) priming: full irrigation from transplanting to flowering onset (FO) followed by a priming process from FO to harvest. The priming process consisted of three water restriction periods of increasing length (8, 11, and 14 days) followed each by a recovery period of 14 days with full irrigation. Potential stress memory induction was calculated for each accession based on ecophysiological indicators such as senescence, foliar area, leaf-minus-air temperature, and leaf 13C discrimination. Based on total biomass production, resilience and production capacity were calculated per accession to evaluate drought tolerance. Increase in foliar area, efficient leaf thermoregulation, improvement of leaf photosynthetic performance, and delayed senescence were identified in 23.7, 28.8, 50.8, and 81.4% of the total number of accessions, respectively. It was observed that under a severe drought scenario, a resilient response included more long-lived green leaf area while a productive response was related to optimized leaf thermoregulation and gas exchange. Our preliminary results suggest that I. triloba and I. trifida have the potential to improve sweetpotato resilience in dry environments and should be included in introgression breeding programs of this crop. Furthermore, I. splendor-sylvae, I. ramosissima, I. tiliacea, and wild I. batatas were the most productive species studied but given the genetic barriers to interspecific hybridization between these species and sweetpotato, we suggest that further genetic and metabolic studies be conducted on them. Finally, this study proposes a promising method for improving drought tolerance based on potential stress-memory induction, which is applicable both for wild species and crops.

Field Performance of Saccharum × Miscanthus Intergeneric Hybrids (Miscanes) Under Cool Climatic Conditions of Northern Japan

Physiological susceptibility to early- and late-season chilling limits commercial production of sugarcane (Saccharum spp. hybrid), a major crop for lignocellulosic biomass, refined sugar, and bioethanol, to tropical and the warmest subtropical regions. Interspecific and intergeneric hybridization have been used to broaden the genetic base of sugarcane and improve its adaptation to temperate climates. Chilling tolerance can be introgressed in sugarcane through intergeneric hybridization with Miscanthus, a cold-tolerant C4 perennial grass, which is genetically homologous to sugarcane. This study evaluated intergeneric F1 hybrids of Saccharum × Miscanthus, miscanes, which included two genotypes of sugarcane × Miscanthus sinensis and sixteen genotypes of sugarcane × Miscanthus sacchariflorus, for their seasonal variation in photosynthesis and biomass production under field conditions in Hokkaido, Japan, to identify promising genotypes and traits, which can be selected to further improve sugarcane. Results showed several of the miscane genotypes had high early- and late-season photosynthesis coupled with high biomass production, which likely indicates chilling tolerance. High broad-sense heritabilities for traits, including stem diameter, tiller number, leaf width, leaf and stem dry weight, and high correlations between these traits and dry matter yield indicate selections can be made efficiently to improve sugarcane. Although none of the miscanes overwintered at the experimental location, we identified miscane “JM 14-09” as a superior genotype for introgression breeding programs and as a potential energycane cultivar for its high biomass-production capacity.

Addition of Aegilops U and M Chromosomes Affects Protein and Dietary Fiber Content of Wholemeal Wheat Flour

Cereal grain fiber is an important health-promoting component in the human diet. One option to improve dietary fiber content and composition in wheat is to introduce genes from its wild relatives Aegilops biuncialis and Aegilops geniculata. This study showed that the addition of chromosomes 2Ug, 4Ug, 5Ug, 7Ug, 2Mg, 5Mg, and 7Mg of Ae. geniculata and 3Ub, 2Mb, 3Mb, and 7Mb of Ae. biuncialis into bread wheat increased the seed protein content. Chromosomes 1Ug and 1Mg increased the proportion of polymeric glutenin proteins, while the addition of chromosomes 1Ub and 6Ub led to its decrease. Both Aegilops species had higher proportions of β-glucan compared to arabinoxylan (AX) than wheat lines, and elevated β-glucan content was also observed in wheat chromosome addition lines 5U, 7U, and 7M. The AX content in wheat was increased by the addition of chromosomes 5Ug, 7Ug, and 1Ub while water-soluble AX was increased by the addition of chromosomes 5U, 5M, and 7M, and to a lesser extent by chromosomes 3, 4, 6Ug, and 2Mb. Chromosomes 5Ug and 7Mb also affected the structure of wheat AX, as shown by the pattern of oligosaccharides released by digestion with endoxylanase. These results will help to map genomic regions responsible for edible fiber content in Aegilops and will contribute to the efficient transfer of wild alleles in introgression breeding programs to obtain wheat varieties with improved health benefits.Key Message: Addition of Aegilops U- and M-genome chromosomes 5 and 7 improves seed protein and fiber content and composition in wheat.

Interspecific Hybridization between Eggplant and Wild Relatives from Different Genepools

Wild relatives represent a source of variation for many traits of interest for eggplant (Solanum melongena) breeding, as well as for broadening the genetic base of this crop. However, interspecific hybridization with wild relatives has been barely used in eggplant breeding programs. As initiation of an introgression breeding program we performed 1424 interspecific hybridizations between six accessions of eggplant from the Occidental and Oriental groups and 19 accessions of 12 wild species from the primary (Solanum incanum and Solanum insanum), secondary (Solanum anguivi, Solanum dasyphyllum, Solanum lichtensteinii, Solanum linnaeanum, Solanum pyracanthos, Solanum tomentosum, and Solanum violaceum), and tertiary (Solanum elaeagnifolium, Solanum sisymbriifolium, and Solanum torvum) genepools. Fruit set, hybrid seed, and seed germination were obtained between Solanum melongena and all wild species of the primary and secondary genepools. The highest fruit set percentage and quantity of seeds per fruit were obtained with the two primary genepool species S. incanum and S. insanum as well as with some secondary genepool species, like S. anguivi, S. dasyphyllum, or S. lichtensteinii, although some differences among species were observed depending on the direction of the hybridization. For small-fruited wild species, the number of seeds per fruit was lower when using them as maternal parent. Regarding tertiary genepool species, fruit set was obtained only in interspecific hybridizations of eggplant with S. sisymbriifolium and S. torvum, although the fruit of the former were parthenocarpic. However, it was possible to rescue viable interspecific hybrids with S. torvum. In total we obtained 58 interspecific hybrid combinations (excluding reciprocals) between eggplant and wild relatives. Some differences were observed among S. melongena accessions in the degree of success of interspecific hybridization, so that the number of hybrid combinations obtained for each accession ranged between 7 (MEL2) and 16 (MEL1). Hybridity of putative interspecific hybrid plantlets was confirmed with a morphological trait (leaf prickliness) and 12 single nucleotide polymorphism markers. The results show that eggplant is amenable to interspecific hybridization with a large number of wild species, including tertiary genepool materials. These hybrid materials are the starting point for introgression breeding in eggplant and in some cases might also be useful as rootstocks for eggplant grafting.

Construction of genetic linkage map and graphical genotyping of pseudo-backcrossed F2 (BC’2) progeny to introduce a CTV resistance from Poncirus trifoliata (L.) Raf. into Citrus by introgression breeding

Most citrus tristeza virus (CTV) strains infect almost all Citrus species and have caused serious damage on citrus production in many countries. Poncirus trifoliata (trifoliate orange) has a single dominant resistance gene effective against a broad range of CTV strains. P. trifoliata is sexually compatible with Citrus species, and introgression breeding programs have been initiated to introduce the CTV resistance into Citrus. “Kankitsu Chukanbohon Nou 8 Gou” (Nou-8) was developed by crossing Citrus sp. “Kiyomi” with an F1 hybrid derived from Citrus hassaku × P. trifoliata, but it still had undesirable eating traits. In aim to progress marker-assisted introgression breeding for CTV resistance efficiently, we selected 189 DNA markers which could be applied to genotyping for Citrus and P. trifoliata and constructed a genetic linkage map of Nou-8. The map included 189 DNA markers on 10 linkage groups and extended about 722.8 cM in total length. CTV resistance locus was located at 2.4 cM position in linkage group 02_(1), with the same location found when progeny were scored for resistance using an ELISA assay and for DNA marker for CTV resistant (CTV103). Graphical genotypes of Nou-8 and its progeny suggested that (1) 36 % of the chromosome in the BC’2 population were inherited from Nou-8 without any recombination sites, (2) Nou-8 had been already completely substituted by Citrus genotype in two linkage groups, and (3) four of 93 progeny of Nou-8 had recombination sites in the flanking region of the CTV resistance gene locus.

Verification of Progeny from Crosses Between Sugarcane (Saccharum spp.) and an Intergeneric Hybrid (Erianthus arundinaceus × Saccharum spontaneum) with Molecular Makers

To incorporate genes from wild germplasm for broadening the genetic base of sugarcane, crosses of sugarcane (Saccharum spp.) × an intergeneric hybrid (Erianthus arundinaceus × Saccharum spontaneum) were carried out and their progenies were identified by sequence-related amplified polymorphism (SRAP) and microsatellite (SSR) molecular markers. A total of 56 SRAP primers and 167 SSR primers were screened and 1 primer pair of each was selected for identification. All 34 progeny were confirmed as hybrids and the results opened opportunities to utilise both S. spontaneum and E. arundinaceus in introgression breeding programs to improve sugarcane.

Genetic and Evolutionaty Relationship Among Nicotiana Secies as Elucidated by AFLP

Twenty two species representing three subgenera of the genus Nicotiana and two interspecific hybrids were analysed by AFLP. A total of 554 bands were amplified by 6 primer pairs, of which 541 (97.65%) were polymorphic and 13 (2.34%) monomorphic. The primer combination E-AAC/M-CTG gave the highest polymorphic information content (PIC) across all species, whereas E-AAG/M-CAC gave the lowest PIC score. A total of 59 species specific markers were generated, of which 54, 4 and 1 were specific to subgenera Petunioides, Tabacum and Rustica respectively. The pair-wise similarity measure in the species of subgenus Rustica was 0.35 whereas it was 0.29-0.50 in subgenus Tabacum, suggesting that there was significant diversity among the species of these subgenera. In the species of subgenus Petunioides, the range of pair-wise similarity measure was 0.25 to 0.95. The high genetic similarity (95%) was due close relationship among the species belonging to the sections Rependae and Trigonophyllae. Sub-grouping of the species within the main clusters of dendrogram was largely based on the chromosome number. AFLP was found efficient in determining the extent of interspecific genetic diversity existing in genus Nicotiana. The subgenus and species specific AFLP markers identified in this study would be useful in introgression breeding programs of tobacco. N. tabacum shared 174/198 AFLP fragments with the two progenitor species, thus providing molecular evidence that these two wild species contributed genetic information to N. tabacum. The Journal of Agricultural Sciences, 2012, vol.7, no3, page 135-144 DOI: http://dx.doi.org/10.4038/jas.v7i3.4877

Simultaneous improvement and genetic dissection of grain yield and its related traits in a backbone parent of hybrid rice (Oryza sativa L.) using selective introgression

Three populations with a total of 125 BC2F3:4 introgression lines (ILs) selected for high yields from three BC2F2 populations were used for genetic dissection of rice yield and its related traits. The progeny testing in replicated phenotyping across two environments and genotyping with 140 polymorphic simple sequence repeat markers allowed the identification of 21 promising ILs that had significantly higher yields than the recurrent parent Shuhui527 (SH527). A total of 94 quantitative trait loci (QTL) were identified using the selective introgression method based on Chi-squared (χ2) and multi-locus probability tests and the RSTEP-LRT method based on stepwise regression. These QTL were mostly mapped to 12 clusters on seven rice chromosomes. Several important properties of the QTL affecting grain yield (GY) and its related traits were revealed. The first one was the presence of strong and frequent non-random associations between or among QTL that affect low-heritability traits (GY and spikelet number per panicle, SN) in the ILs with high trait values. Second, beneficial alleles at 88.9 % GY and 75 % SN QTL for increased productivity were from the donors, suggesting that direct phenotypic selection for high yield in our introgression breeding program was a powerful way to transfer beneficial alleles at many loci from the donors into SH527. Third, most QTL were in clusters with large effects on multiple traits, which should be the focal points in further investigations and marker-assisted selection in rice. The majority of the QTL identified were expressed only in one of the environments, suggesting that differential expression of QTL in different environments is the primary genetic basis of genotype × environment interaction. Finally, a large variation in both the direction and magnitude of QTL effects was detected for different donor alleles at seven QTL in the same genetic background and environments. This finding suggests the possible presence of functional diversity among the donor alleles at these loci. The promising ILs and QTL identified provide valuable materials and genetic information for further improving the yield potential of SH527, which is a backbone restorer of hybrid rice in China.

Assembly of 500,000 inter-specific catfish expressed sequence tags and large scale gene-associated marker development for whole genome association studies

Twelve cDNA libraries from two species of catfish have been sequenced, resulting in the generation of nearly 500,000 ESTs.

Central cell nuclear-cytoplasmic incongruity:a mechanism for segregation distortion in advanced backcross and selfed generations of (Allium cepa L. × Allium fistulosum L.) × A. cepa interspecific hybrid derivatives

A model is presented as an explanation for an anomaly observed in germination and establishment and isozyme segregation patterns in Allium cepa × A. fistulosum F₂BC₃ populations generated in an introgression-breeding program. The F₁BC₃ parent of these populations was selected for its heterozygous PGI phenotype, Pgi-1^2/3; Pgi-1² was inherited from an A. cepa (Ac) seed parent and Pgi-1³ from an A. fistulosum (Af) pollen parent. Germination and establishment was recorded for the F₂BC₃ progeny population. Segregation of Ac and Af Pgi-1 alleles was investigated in F₂BC₃ seeds and embryo and endosperm tissue was isolated and tested for isozyme expression. A pooled goodness-of-fit test of the segregation of Pgi-1 alleles in the populations to the expected Mendelian 1:2:1 ratio using the chi-square statistic gave a χ² = 185.9, well beyond the accepted limits at 2 degrees of freedom. The 1:2:1 ratio expected for simple Mendelian inheritance was rejected, while a pooled chi-square goodness-of-fit test of the segregation of Pgi-1 alleles in the populations fit a 1:1 ratio with a χ² = 0.203, based on the incongruity model. We present here the central cell nuclear-cytoplasmic incongruity hypothesis to explain the observed anomalies.

A Model for Marker‐Based Selection in Gene Introgression Breeding Programs

Marker‐based breeding can be useful to expedite introgression of specific genetic material from a donor parent into the background of an elite variety, through backcrossing. A model is proposed to predict the probability of donor parent genetic material being present in specific regions of the genome, and its proportion at the chromosome‐specific or whole genome levels, as a result of marker‐based introgression. Furthermore, formulas are provided to calculate the variance of the predicted values. Two kinds of markers are considered: donor parent specific and recurrent parent specific. The first type serves to introgress the desired fraction of donor genome, and the second one to recover the recurrent parent background genome. In all cases, the probabilities and genomic proportions are calculated on a genetic map basis. This model permits any localization of markers through the genome, but requires knowledge of their map positions and the map lengths of the chromosomes. It is robust to mapping functions, and admits any one based on the assumption of coincidence being equal to the kth power of twice the recombination fraction. Two widely used mapping functions gave fairly different predictions of global chromosome introgression. Monte Carlo simulations for several circumstances allowed the testing of the model, and no significant statistical deviations from the theoretical predictions were found. The results indicate that the formulas presented herein can be useful for planning and prediction in a backcross breeding program.

Chromosomal characterization and physical mapping of the 5S and the 18S-5.8S-25S ribosomal DNA in Helianthus argophyllus, with new data from Helianthus annuus

The characterization of the mitotic chromosomes of Helianthus argophyllus by means of Feulgen staining, Giemsa C-banding, and the usual DNA sequence-specific fluorochromes allows a chromosomal classification of this species, and shows that two kinds of heterochromatin co-exist equilocally in its chromosomes. One type is confined to the pericentromeric areas of all the chromosomes and the other is associated with the secondary constrictions of the satellite chromosomes. This species is evolutionarily very close to H. annuus with which it is involved in introgression breeding programs. Since these two species show no intra- or interspecific differences with the above treatments, we have used C-banding followed by DAPI, chromomycin A3 or Acridine Orange, and the fluorescent in situ hybridization (FISH) with 5S and 18S-25S ribosomal DNA probes to characterize further the chromosomes of both species in an attempt to find practically applicable chromosomal markers. Our results confirm the heterogeneity of the heterochromatin in these species and show that neither its distribution nor its response to distinct fluorochrome treatments allows better discrimination of the chromosomes within or between the species. On the other hand, the 18S-5.8S-25S rDNA arrays are located in the secondary constrictions of the satellited SM7, SM10, and ST13 pairs and the 5S-rDNA genes are interstitially placed on the short arm of the SM7 and SM11 chromosomes in both species. This permits these chromosomes to be distinguished and provides markers which may be helpful for further physical mapping of DNA sequences in these species.Key words: chromosome banding, sunflower cytogenetics, heterochromatin, ribosomal DNA mapping, FISH.

Using markers in gene introgression breeding programs.

We investigate the use of markers to hasten the recovery of the recipient genome during an introgression breeding program. The effects of time and intensity of selection, population size, number and position of selected markers are studied for chromosomes either carrying or not carrying the introgressed gene. We show that marker assisted selection may lead to a gain in time of about two generations, an efficiency below previous theoretical predictions. Markers are most useful when their map position is known. In the early generations, it is shown that increasing the number of markers over three per non-carrier chromosome is not efficient, that the segment surrounding the introgressed gene is better controlled by rather distant markers unless high selection intensity can be applied, and that selection on this segment first can reduce the selection intensity available for selection on non-carrier chromosomes. These results are used to propose an optimal strategy for selection on the whole genome, making the most of available material and conditions (e.g., population size and fertility, genetic map).

DNA fingerprints applied to gene introgression in breeding programs.

An application of DNA fingerprints (DFP) for gene introgression in breeding programs of both farm animals and plants is proposed. DFP loci, detectable by minisatellite probes, are extremely polymorphic. Individuals have unique patterns of DFP and thus can be selected for maximal genomic similarity to the recipient line, and minimal similarity to the donor line, using their DFP patterns as the criterion for similarity. This genomic selection (GS) can be performed at generations BC1, BC2 or both, and thus significantly reduce the required number of backcross generations in introgression breeding programs. The association between genomic and DFP similarity is demonstrated. Theoretical distributions and variances of the relative percentages of the donor and recipient genomes as the basis for the GS approach are presented.