Overview What is Plant Breeding? Basic Genetics Mendelian Genetics Principles of Breeding Plant Breeding Methods Molecular breeding introduction

Plant Breeding Molecular breeding introduction What is it? Is the science and art of improving crop plants through the study and application of genetics, agronomy, statistics, plant pathology, entomology, and other related sciences. Goals Nutritional enhancement, yield improvement, environmental stress tolerance, improved plant structure, or pest and disease resistance Molecular breeding introduction

OBJECTIVE OF THE SUBJECT understand the developments in plant breeding and the state of the art breeding practices (ornamentals vs. crops) have some knowledge on the basics of genetics (Mendel, QTL etc.) and understand the idea and the potential of genetic engineering have some understanding on the concepts of molecular breeding have some (practical) knowledge to apply molecular markers for the identification of traits in the genome be able to determine whether information from the internet regarding modern breeding methods are relevant and informative Molecular breeding introduction

Selected milestones in plant breeding 1714 Mather observed natural crossing in maize 1866 Mendel: Experiments in plant hybridization 1900 Mendel’s laws of heredity rediscovered 1944 Avery, MacLeod, McCarty discovered DNA is hereditary material 1953 Watson, Crick, Wilkins proposed a model for DNA structure 1970 Borlaug received Nobel Prize for the Green Revolution Berg, Cohen, and Boyer introduced the recombinant DNA technology 1994 ‘FlavrSavr’ tomato developed as first GMO 1995 Bt-corn developed Molecular breeding introduction

Importance of plant breeding Difference in : - yield - content - germination - maturation - resistance Importance of plant breeding 1.Increased quality and yield of the crop 2. Increased tolerance of environmental pressures (salinity, extreme temperature, drought) 3. Resistance to viruses, fungi and bacteria 4. Increased tolerance to insect pests 5. Increased tolerance of herbicides Molecular breeding introduction

Molecular breeding introduction

Basic Plant Genetics DNA Primary carries of heritable information Composed of thousands of genes

Molecular breeding introduction

Molecular breeding introduction

Basic Plant Genetics There are two alleles for any gene Dominant and Recessive Two dominant alleles are denoted as “AA” and called homozygous dominant Two recessive alleles are denoted as “aa” and called homozygous recessive If one dominant and one recessive allele is present then it is denoted as “Aa” and called heterozygous. Molecular breeding introduction

Basic Plant Genetics Alleles which are heterozygous or homozygous affect the phenotypes and genotypes of plants Phenotype Visual appearance of the plant Genotype Genetic makeup of the plant Molecular breeding introduction

Mendelian Genetics Gregor Mendel Famous geneticist from 1800’s His research consisted of selectively breeding garden peas He developed two important laws of genetics Law of Segregation Law of Independent Assortment Molecular breeding introduction

Mendelian Genetics Molecular breeding introduction

Principles of Breeding Three Main Principles Inbreeding Hybridization Heterosis Steps of Plant Breeding plant breeding; Creation of variation Selection Evaluation Release Multiplication Distribution of the new variety Molecular breeding introduction

Inbreeding Main Goals Increase the homozygosity at all or specific loci in the plant genome Produce a plant which breeds true Produce uniform plants Molecular breeding introduction

Hybridization Hybridization occurs when inbred parents are mated (cross pollinated) Creates a heterozygous individual Benefits Increased heterosis (vigor) in F1 generation Molecular breeding introduction

Heterosis Heterosis occurs when two homozygous individuals are cross pollinated. This causes all loci to become heterozygous The increased heterozygosity causes increased plant vigor Benefits of Increased Vigor Increased yield Better standability Better germination Overall better plant performance Molecular breeding introduction

Breeding Methods Main Methods of Breeding Selfing (Inbreeding) Sib Mating Crossing Test Crossing Backcrossing Molecular breeding introduction

Selfing Selfing is the process of pollinating a plant with its own pollen Benefits Increased homozygosity Plants which breed true from generation to generation Decreased Segregation Disadvantages Many generations of selfing lead to inbreeding depression Molecular breeding introduction

Molecular breeding introduction

Crossing and Test Crossing Crossing is useful when trying to create hybrid seed. Ex. By crossing “Inbred A x Inbred a” you would obtain an F1 hybrid Aa Crossing is used to produce the hybrid seed farmers use to plant in the spring Test Crossing is useful to test general combining ability of an individual Ex. Inbred A is x to a tester which has a diverse selection of genotypes Molecular breeding introduction

Molecular breeding introduction

Backcrossing Backcrossing is a method which is used to improve a trait which a plant is deficient in. Method A hybrid plant which has the trait of interest is crossed with one of its parents The offspring are then crossed back to the parent, thus increasing the frequency of the trait. Molecular breeding introduction

Scientific disciplines and technologies of plant breeding Genetics Botany Plant physiology Agronomy Pathology and entomology Statistics Biochemistry Molecular breeding introduction

Classic/ traditional tools Emasculation Hybidization Wide crossing Selection Chromosome counting Chromosome doubling Male sterility Triploidy Linkage analysis Statistical tools Advanced tools Mutagenesis Tissue culture Haploidy In situ hybridization DNA markers Molecular breeding introduction

Advanced technology Molecular markers Marker-assisted selection DNA sequencing Plant genomic analysis Bioinformatics Microarray analysis Primer design Plant transformation

Conclusion Plant breeding is a complicated but beneficial process. There are many processes involved which are used in the development of new varieties. Remember if it wasn’t for plant breeding we wouldn’t have such high yielding crops

Mendal’s law of genetics Next topic: Mendal’s law of genetics Mendal’s law of genetics