Conventional Breeding Approaches

Genomic selection and breeding

breeding method that uses genomic information, specifically data from a large number of genetic markers across the genome, to predict the genetic potential of individuals for specific traits.

Genomic selection and breeding

•allows breeders to estimate the breeding values of individuals based on their genetic makeup

•utilizes genome-wide markers to predict the genetic potential of individuals

Conventional Breeding Approaches (Traditional/Classical Breeding)

process of selecting and propagating plants or animals based on observable traits (phenotypes) and genetic relationships (pedigree) to enhance desirable characteristics in future generations.

Conventional Breeding Approaches (Traditional/Classical Breeding)

relies on natural reproductive processes and does not involve modern biotechnological techniques

• Pure-line selection

• Mass selection,

• Backcross breeding

• Recurrent selection

• Hybridization

Mechanism of Conventional Breeding

Hybridization

-Involves selecting individual plants with desirable traits and self-pollinating them over several generations.

Mass selection

•Involves selecting a group of plants based on their overall performance and desirable traits.

Backcross breeding

Used to transfer a specific trait from one plant to another. Involves crossing a hybrid offspring back to one of its parent plants.

Recurrent selection

•Used to improve a population by repeatedly selecting and interbreeding individuals with desirable traits. Involves multiple cycles of selection and breeding to enhance specific traits over generations.

Hybridization

Involves crossing two genetically distinct parent plants to produce hybrid offspring

F1

_________ hybrids often exhibit heterosis or hybrid vigor, leading to improved yield and resilience.

Ancient selection & domestication (10,000 BCE – 170s CE)

•Early humans selected plants and animals for desirable trait.

•Method: Artificial selection (saving best seeds, breeding best animals)

Wheat, rice, maize

First domesticated crops during Ancient selection & domestication (10,000 BCE – 170s CE)

Cattle, sheep, goat

First domesticated animals during Ancient selection & domestication (10,000 BCE – 170s CE)

Pre-Mendelin Breeding (1700S – MID-1800S)

•Farmers practiced crossbreeding without scientific knowledge

•Robert Bakewell developed selective livestock breeding

•Traits improved: Higher yield, better taste, disease resistance

Robert Bakewell

developed selective livestock breeding

Mendelian Genetics and Classical Breeding (Mid-1800S – EARLY 1900S)

•Gregor Mendel’s Laws of Inheritance (1860s)

•Hybridization of crops (corn, wheat, rice)

•Discovery of recessive & dominant traits → helped breed disease- resistant varieties

Eary 20th Century – Systematic Breeding & Hybrid Vigor

•Rediscovery of Mendel’s work (1900) → foundation of modern breeding

•Heterosis (Hybrid Vigor): Improved growth & yield (e.g., hybrid maize)

•Livestock improvements: Dairy cows with higher milk production

Green Revolution & Intensive Breeding (1940s – 1970s)

•Norman Borlaug & high-yield wheat (saved millions from famine)

•Mutation breeding: Radiation used to induce beneficial mutations

•Livestock breeding: Disease-resistant, high-meat yield animals

At 20th Century – Modern Refinements

•Marker-Assisted Selection (MAS): Faster & more precise breeding

•Drought-resistant & pest-resistant varieties developed

1. Ensure food security and safety

2. Produce organisms that are resistant of pest and diseases

3. develop organisms that are tolerant to environmental stresses

4. Develop organisms that are of high quality

The Role of Conventional Breeding Approach in Crop Improvement is to

Ensure Food Security and Safety (Kaiser et al., 2020)

Production of IR64

•A high yielding rice variety developed by the international rice research institute through backcross breeding to address challenges in rice production, as well as improve food security specifically in places that uses rice as their staple (Mackill & Khush, 2018).

Produce Organism that are resistance of Pest and Diseases

Karan Vandana (DBW 187)

•A high yield, disease resistant, and high iron content developed by the Indian Institute of Wheat and Barley Research (IIWBR) that addresses both agronomic and nutritional challenges (Staff, n.d.).

Develop Organisms that are of High Quality

Sweet corn (Honey select)

•A maize variety developed by the Syngenta Vegetable seed that is sweet, tender, an appearance with a superior quality, and has longer shelf life (Honey Select, n.d.).

Marker-assisted selection (MAS)

•Uses DNA to select desirable traits in plants and animals this accelerates breeding by identifying genetic features early

1. Faster breeding

2. Accurate detection

3. Reduces environmental influence

4. Improves resistance

Benefits of MAS

1. DNA Extraction

2. Maker Analysis

3. Trait Prediction

MAS Mechanism

DNA Extraction

Marker-assisted selection (MAS) uses DNA markers to select for desirable traits in breeding programs, allowing for earlier selection and potentially faster gains than traditional methods.

Marker Analysis

the process of identifying and analyzing molecular markers—specific DNA sequences that are associated with particular traits of interest in plants or animals.

Trait Prediction

the capacity to anticipate whether an organism (often a plant or animal) will express a given feature based on the presence of molecular markers in its DNA —before the trait becomes physically observable.

1. SNPs (Single Nucleotide Polymorphism)

2. AFLPs (Amplified Fragment Length Polymorphisms)

3. SSRs (Simple Sequence Repeats)

Types of Markers used

SSRs (Simple Sequence Repeats)

aka microsatellites, are short, repeating DNA sequences that are highly polymophic and distributed throughout the genome.

AFLPs (Amplified Fragment Length Polymorphisms)

detect DNA polymosphisms by combininng restrictionenzyme digestion and selctive PCR amplification

SNPs (Single Nucleotide Polymorphism)

the variations in a single nucleotide at a specific position in the genome

1. Disease resistant

2. Insect Resistant

3. Stress tolerance

4. Quality Traita

5. Gene pyramiding

Application in Crop

Disease resistant

identify and selects plants with genes conferring resistance to specific diseases that reduces crop loss and minimize the pesticide use.

Insect Resistant

identify plants with genes that provide protection againsts insect pests.

Stress tolerance

helps identify plants with genes that enable them to tolerate abiotic stresses, such as drought, salinity or extreme temperature

Quality Traits

improving traits like grains quality, nutritional content, or yield

Gene pyramiding

a process that facilitates the combining of multiple desirable genes into single genotype, accumulating beneficial traits and enhancing overall crop performance

1. Increased efficiency

2. Enhanced precision

3. Improved Accuracy

4. Cost-effectiveness

Improvements and Advancements