agridif.com Backcross breeding targets the introgression of specific desirable genes from a donor parent into an elite cultivar background, making it ideal for traits controlled by one or few major genes such as disease resistance. Pedigree breeding involves selecting superior individuals from segregating populations across generations, which allows for the accumulation of multiple favorable alleles and polygenic traits, resulting in broadly adapted cultivars. Backcross breeding is faster for incorporating known traits, while pedigree breeding provides greater genetic diversity and long-term improvement potential.
Table of Comparison
| Aspect | Backcross Breeding | Pedigree Breeding |
|---|---|---|
| Purpose | Introduce one specific desirable gene into a well-adapted cultivar | Develop new cultivars by selecting superior individuals over multiple generations |
| Genetic Background | Maintains most of recurrent parent genome | Creates new genetic combinations from diverse parents |
| Selection Process | Repeated backcrossing and selection for target trait | Selection based on phenotype and pedigree records over generations |
| Number of Parents | Two (donor and recurrent parent) | Two or more diverse parents |
| Time Required | Faster due to focused trait introgression | Longer due to multiple generations and extensive selection |
| Application | Trait improvement such as disease resistance, quality trait introgression | Developing new varieties with improved yield, quality, and adaptation |
| Genetic Variation | Limited variation, near-isogenic lines | High genetic variability for selection |
| Complexity | Simple and targeted | Complex with multiple traits and recombination |
Introduction to Plant Breeding Methods
Backcross breeding targets the transfer of specific desirable genes from a donor parent into an elite cultivar, ensuring rapid recovery of the recurrent parent's genome, ideal for incorporating disease resistance or quality traits. Pedigree breeding involves the selection of superior plants over successive generations, focusing on multiple trait improvement and genetic variability within segregating populations for cultivar development. Both methods are fundamental in plant breeding, with backcross breeding excelling in precise trait introgression and pedigree breeding supporting broad genetic enhancement.
Overview of Backcross Breeding
Backcross breeding is a genetic improvement method primarily used to introduce or recover a specific desirable trait in an elite cultivar by repeatedly crossing the hybrid progeny with one of its parents, known as the recurrent parent. This technique efficiently transfers a single gene or a few genes for traits like disease resistance or quality traits while preserving the recurrent parent's genome background. The process boasts a high recovery rate of the recurrent parent's phenotype, making it especially valuable for improving well-established cultivars with minimal genetic disruption.
Fundamentals of Pedigree Breeding
Pedigree breeding involves selecting and advancing individual plants based on superior phenotypic traits through successive generations, allowing detailed tracking of genetic inheritance and heterozygosity. This method emphasizes controlled crossing and rigorous evaluation of progeny, enabling the development of stable, high-performing cultivars with complex traits. Backcross breeding, in contrast, primarily introgresses specific genes from a donor into an elite cultivar, but pedigree breeding provides a broader basis for improving multiple traits simultaneously.
Genetic Principles Underlying Both Methods
Backcross breeding involves transferring a specific gene or trait from a donor parent into a well-adapted recurrent parent through repeated backcrossing, leveraging the principle of introgression and maintaining most of the recurrent parent's genome. Pedigree breeding relies on selecting superior individuals from segregating populations derived from the initial cross of two parents, emphasizing genetic recombination and segregation to accumulate favorable alleles over successive generations. Both methods exploit Mendelian inheritance, with backcross breeding focusing on preserving elite genetic backgrounds while introducing specific traits, whereas pedigree breeding enhances genetic variation for cumulative selection of complex traits.
Step-by-Step Process: Backcross Breeding
Backcross breeding involves crossing a hybrid offspring back to one of its parents to introduce or reinforce specific desirable traits, primarily focusing on transferring a single gene or trait into an elite cultivar. The step-by-step process includes selecting a recurrent parent with superior agronomic qualities, crossing it with a donor parent harboring the desired trait, and subsequently backcrossing the progeny with the recurrent parent through multiple generations while selecting for the target trait. Marker-assisted selection can accelerate this process by identifying individuals with the desired gene, ultimately resulting in a cultivar nearly identical to the recurrent parent but with improved characteristics.
Step-by-Step Process: Pedigree Breeding
Pedigree breeding involves selecting superior individual plants from each generation and recording their ancestry to consistently enhance desired traits across successive generations. The step-by-step process includes crossing two parents with contrasting traits, followed by selfing and selecting progeny through several generations to fix desirable alleles and eliminate undesirable ones. This method allows for detailed tracking of genetic inheritance and precise improvement of complex traits in cultivar development.
Key Differences Between Backcross and Pedigree Breeding
Backcross breeding primarily focuses on transferring one or a few desirable genes from a donor parent into an elite recipient cultivar, maintaining most of the recipient's genetic background, while pedigree breeding involves selecting superior individuals from a segregating population derived from crossing two parents, aimed at developing new cultivars with enhanced traits through multiple generation selections. Backcross is efficient for introgressing specific traits such as disease resistance or quality traits into established varieties, whereas pedigree breeding is suitable for combining diverse traits and creating genetic variability for complex trait improvement. The key differences lie in the genetic background retention, number of generations needed, and the breeding goals focused on trait introgression versus novel cultivar development.
Advantages and Limitations of Backcross Breeding
Backcross breeding excels in rapidly transferring specific desirable genes from a donor to a well-adapted cultivar, ensuring high genetic similarity to the recurrent parent and preserving elite traits. Its advantages include precise gene introgression and the ability to improve single genes controlling disease resistance or quality traits, but it is limited by reduced genetic diversity and slower development of polygenic traits. The method's effectiveness diminishes when multiple traits with complex inheritance are targeted, often requiring complementary approaches like pedigree breeding for broad genetic improvement.
Advantages and Limitations of Pedigree Breeding
Pedigree breeding enables precise selection of desirable traits through controlled hybridization and detailed tracking of ancestry, facilitating the development of cultivars with improved genetic diversity and complex trait combinations. This method effectively manages genetic variability and accelerates the identification of superior genotypes, especially in self-pollinating crops. However, pedigree breeding requires extensive record-keeping and multiple generations, making it time-consuming and labor-intensive compared to backcross breeding, which is more efficient for incorporating specific traits from donor parents.
Applications and Suitability in Cultivar Development
Backcross breeding is primarily applied for transferring specific traits, such as disease resistance or quality attributes, from a donor parent into an elite cultivar with a well-established genetic background, making it highly suitable for improving single or few target genes. Pedigree breeding is more effective for developing cultivars with complex, polygenic traits like yield or stress tolerance, as it allows for the selection and recombination of multiple desirable traits over successive generations. The choice between backcross and pedigree breeding depends on the breeding objective, with backcross breeding fitting trait introgression and pedigree breeding optimizing genetic variation for enhanced cultivar performance.
Related Important Terms
Marker-Assisted Backcrossing (MABC)
Backcross breeding, especially Marker-Assisted Backcrossing (MABC), accelerates the introgression of specific genes into elite cultivars by precisely selecting progenies with desired traits using molecular markers, thereby reducing linkage drag and breeding cycles. In contrast, pedigree breeding relies on phenotypic selection across generations without molecular guidance, making it time-consuming and less efficient for incorporating targeted genes in cultivar development.
Genomic Selection in Backcrossing
Backcross breeding leverages genomic selection to efficiently introgress specific genes from a donor into an elite cultivar background, accelerating the recovery of the recurrent parent's genome while retaining target traits. In contrast, pedigree breeding involves tracking and selecting multiple generations based on phenotypic performance and genetic markers, making it less precise and slower compared to the high-resolution, genome-wide prediction models used in backcross genomic selection.
Pedigree-Based Genomic Prediction
Pedigree-based genomic prediction enhances cultivar development by leveraging the genetic relationships and inheritance patterns within breeding populations, improving the accuracy of selecting superior genotypes. Compared to backcross breeding, this method accelerates the identification of elite lines by integrating high-density genomic data with detailed pedigree information, optimizing genetic gain within fewer generations.
Rapid Generation Advancement (RGA)
Backcross breeding efficiently introgresses specific traits into elite cultivars by repeatedly crossing progeny with the recurrent parent, accelerating trait fixation through Rapid Generation Advancement (RGA) techniques such as doubled haploids and off-season nurseries. Pedigree breeding tracks the inheritance of multiple traits across generations, with RGA expediting cultivar development by reducing generation time and enhancing selection accuracy for complex trait combinations.
Accelerated Backcrossing
Accelerated backcrossing enhances cultivar development by rapidly introgressing specific traits from donor to recipient plants while minimizing linkage drag through marker-assisted selection, making it more efficient than conventional pedigree breeding that relies on phenotypic selection over multiple generations. This targeted approach reduces breeding cycles and increases genetic gain, allowing faster development of improved cultivars with desired characteristics such as disease resistance or stress tolerance.
Double Haploid Pedigree Lines
Backcross breeding is primarily used for introgressing specific traits from a donor into a recurrent parent, whereas pedigree breeding involves selecting superior individuals over successive generations to develop improved cultivars. Double haploid pedigree lines accelerate genetic fixation and uniformity, enhancing the efficiency of pedigree breeding by producing homozygous lines in a single generation, which is less feasible in backcross breeding approaches.
Residual Heterozygosity in Backcross Populations
Backcross breeding maintains higher residual heterozygosity levels compared to pedigree breeding, facilitating the introgression of specific traits while preserving the genetic background of the recurrent parent. In contrast, pedigree breeding reduces heterozygosity through successive selfing, enhancing trait fixation but limiting genetic diversity in cultivar development.
Multi-parent Advanced Generation Intercross (MAGIC) in Pedigree Breeding
Backcross breeding efficiently transfers specific traits from a donor to a recurrent parent by repeated crossing, ideal for single-gene introgression, whereas Pedigree breeding incorporates genetic recombination and selection over multiple generations to develop cultivars with complex, polygenic traits. The Multi-parent Advanced Generation Intercross (MAGIC) population in Pedigree breeding enhances genetic diversity by intercrossing multiple founder lines, facilitating high-resolution mapping of quantitative trait loci (QTLs) and accelerating the development of superior cultivars.
Background Genome Recovery Rate
Backcross breeding achieves a higher background genome recovery rate by repeatedly crossing progeny with the recurrent parent, ensuring faster restoration of the desirable genetic background, often exceeding 90% after three to four backcross generations. In contrast, pedigree breeding involves tracking and selecting among diverse segregating populations, resulting in a slower and less precise recovery of the background genome, with considerable genetic variation retained.
Genomic Introgression Mapping
Backcross breeding utilizes genomic introgression mapping to efficiently transfer specific desirable genes from a donor parent into an elite cultivar, enabling precise identification and selection of introgressed genomic segments. Pedigree breeding relies on extensive phenotypic and genotypic evaluations across multiple generations but offers less resolution in tracking introgressed alleles compared to the targeted genomic introgression mapping applied in backcross strategies.
Backcross breeding vs Pedigree breeding for cultivar development Infographic
