INTRODUCTION TO INTRODUCTION TO PLANT MOLECULAR GENETICSPLANT MOLECULAR GENETICS

Why young breeders Why young breeders must study genetics?must study genetics?

GeneticsGenetics Branch of biology dealing with heredity Branch of biology dealing with heredity

and variationand variation Branch of biology dealing with the study Branch of biology dealing with the study

of the geneof the geneCenter of Genetics: Unit of heredity Nucleic acid Protein synthesis Characteristics

of organisms Relationship

between genes and traits

Genetics is a broad disciplineIt encompasses

molecular, cellular, organism, and population

Three Major Areas of GeneticsThree Major Areas of Genetics

Classical Genetics(Transmission)

Molecular Genetics

Evolutionary Genetics

Mendel’s Principles

Genom Quantitative Genetics

Meiosis + mitosis

DNA structure Population Genetics

Sex determination

Chemistry of DNA

Evolution

Sex linkage Gene expression Speciation

Chromosomal mapping

Control of gene expression

Cytogenetics DNA cloning & Marker

Major Subdisciplines of Genetics Transmission Genetics: focuses on the

transmission of genes and chromosomes in individuals from generation to generation.

Molecular Genetics: focuses on the structure and function of genes at the molecular level.

Evolutionary genetics: focus on the study of genetic basis of changes in organism over time

Population Genetics: focuses on heredity in groups of individuals for traits determined by one or only a few genes.

Quantitative Genetics: focuses on heredity in groups of individuals for traits determined by many genes simultaneously.

Molecular Genetics ?Molecular Genetics ? The field of biology that studies the structure and function of genes at a

molecular level. Study of the expression, regulation and

inheritance of genes at the level of DNA and its transcription products

Study of gene structure, function and regulation – below the organism level

Study of genes and how they are expressedStudy of molecular basis of inheritanceMolecular genetics

Basis of Modern Breeding

Modern BreedingModern Breeding  

Systematic procedures used to Systematic procedures used to improve trait phenotypes by improve trait phenotypes by

crossing and selection, directed crossing and selection, directed manipulation of the genotype at manipulation of the genotype at

the DNA sequence level, and the DNA sequence level, and introduction of new genes.introduction of new genes.

Developing suitable cultivarsDeveloping suitable cultivars Each cultivar is developed with special purposeEach cultivar is developed with special purpose

Each cultivar responses differently to environmental changeEach cultivar responses differently to environmental change Climate Change needs special cultivarsClimate Change needs special cultivars

If breeding work fails to help improving resource utilization efficiency and tackling the effect of

global warming, then agriculture will probably not be sustainable and as a result the size of global

community will decline as resources are exhausted and environment is not friendly anymore to human

being (Beversdorf, 1994).

Breeding needs advance technology

Molecular Genetics:A Short History

18691869 Miescher isolated DNA for the first timeMiescher isolated DNA for the first time

19441944 Avery provided evidence that DNA is the Avery provided evidence that DNA is the genetic materialgenetic material

19531953 Watson and Crick proposed the double helix as Watson and Crick proposed the double helix as the structure of DNAthe structure of DNA

19571957 Kornberg discovered DNA polymeraseKornberg discovered DNA polymerase

19611961 Marmer and Doty discovered DNA renaturationMarmer and Doty discovered DNA renaturation

19621962 Arber, Nathans and Smith discovered Arber, Nathans and Smith discovered restriction endonucleasesrestriction endonucleases

19661966 Nirenberg, Ochoa, and Khorana figured out the Nirenberg, Ochoa, and Khorana figured out the genetic code.genetic code.

Molecular Genetics:A Short History

19671967 Geller discovered DNA ligaseGeller discovered DNA ligase

1972-1972-7373

Boyer, Cohen and Berg develop DNA cloning Boyer, Cohen and Berg develop DNA cloning techniquestechniques

19751975 Southern developed gel-transfer hybridizationSouthern developed gel-transfer hybridization

1975-1975-77 77

Sanger and Barrel and Maxam and Gilbert Sanger and Barrel and Maxam and Gilbert developed rapid DNA sequencing methodsdeveloped rapid DNA sequencing methods

1981-1981-82 82

Palmiter and Brinster produced transgenic Palmiter and Brinster produced transgenic mice mice

Spradling and Rubin produced transgenic fruit Spradling and Rubin produced transgenic fruit fliesflies

19851985 Mullis and colleagues invented the Polymerase Mullis and colleagues invented the Polymerase Chain Reaction (PCR)Chain Reaction (PCR)

Molecular Genetics:A Short History

19901990 Human Genome ProjectHuman Genome Project

19951995 Microarray technique by Brown and DavisMicroarray technique by Brown and Davis

20002000 Arabidopsis and Drosophila genome project Arabidopsis and Drosophila genome project

2000 2000 The first gene controlling a quantitative trait is The first gene controlling a quantitative trait is cloned by Tanksleycloned by Tanksley

20022002 The draft of rice genome sequence is publishedThe draft of rice genome sequence is published

2004-2004-20052005

The development of sequencing by synthesis The development of sequencing by synthesis technologytechnology

The The Molecular Molecular Basis of Basis of Inheritance?Inheritance?

The The Molecular Molecular Basis of Basis of Inheritance ?Inheritance ?

Genome Genes, regulatory sequences Others?

The The Molecular Molecular Basis of Basis of Inheritance ?Inheritance ?

RNA

Polypeptides

1.Genome2.Chromosome

3.Gene4.DNA/RNA

5.Nucleic Acid6.Protein

7.Amino Acid

The Molecular Basis of Inheritance?

GenomeTotal genetic information carried by a single set of chromosome in a haploid nucleus

ChromosomeA DNA – histone protein thread, usually associated with RNA, occurring in the nucleus of a cellChromosomes contain hundreds of genes encoded within their DNA.

Genesegment of a chromosome that contains the heredity traits of an organism

DNADouble stranded form of genetic material of organisms

The The Molecular Molecular Basis of Basis of Inheritance ?Inheritance ?

RNA Single stranded form of genetic material of

organisms result of the DNA transcriptionNucleotide

Unit structure of nucleic acidProtein

a polymer that has a high relative molecular mass of amino acids

Polypeptidea linear polymer that consists of ten or more amino acids linked by peptide bonds

Amino AcidAn organic compound containing an acidic carboxyl group and a basic amino group

The The Molecular Molecular Basis of Basis of Inheritance ?Inheritance ?

INTRODUCTION TO MOLECULAR INTRODUCTION TO MOLECULAR GENETICSGENETICS

GenomeGenome Genetic Material (DNA & RNA)Genetic Material (DNA & RNA)

DNA structureDNA structure Chemistry of DNA Chemistry of DNA

Gene expression (transcription and translation)Gene expression (transcription and translation) Control of gene expressionControl of gene expression

Molecular toolMolecular tool DNA cloningDNA cloning DNA markerDNA marker

Grading system

Grade : 0 – 100

A > 80 B – D → 45 – 80 (Normal distribution)

E < 45

Grade composition

Home work : 30

Mid-term : 30

Final Exam : 40