Plant Molecular Genetics and Genetic Transformation HORT 301 – Plant Physiology November 1, 2010 Taiz and Zeiger – Chapter 2, Smith et al. (2010) – Chapter 9 Function of all plant genes – omics; genome, transcriptome, proteome Allelic variation – Le, GA 20 →GA 1 1 Mutations - phenotype
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Plant Molecular Genetics and Genetic Transformation HORT 301 – Plant Physiology November 1, 2010 Taiz and Zeiger – Chapter 2, Smith et al. (2010) – Chapter.
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Plant Molecular Genetics and Genetic TransformationHORT 301 – Plant Physiology
November 1, 2010Taiz and Zeiger – Chapter 2, Smith et al. (2010) – Chapter 9
Function of all plant genes – omics; genome, transcriptome, proteome
Allelic variation – Le, GA20 →GA1
1
Mutations - phenotype
Molecular genetics Genetics – study of heredity/inheritance and function of genetic material Molecular genetics – gene identification, structure and function, biotechnology Genotype – genetic constitution, genesPhenotype – appearance and other function(s) resulting from gene functionGene – functional DNA unit, promoter and coding sequence, i.e. locus
Griffiths AF, et al. 1996. An Introduction to Genetic Analysis. 6th ed.
Locus – usually two alleles at each, contributed by two homologous chromosomes in a diploid (2n) organism, dominant (Y) and recessive (y) alleles
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yy
2
Mutation – change in DNA structure of a gene
WT siz1-2 siz1-3
Mutation may result in loss (reduction in)- or gain-of-function, or may not have an effectFunction is inferred based on deviation from normal
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Smith et al. (2010) Plant Biology
Fruit size regulated by reduced function of a cell division inhibitorPlant breeders improve crops by transferring “mutations” that confer better phenotypes/traits!
Domestication often selects against fitness
Gene function based on gain- or loss-of (reduced)-function by transgene expression
Dwarfism caused by reduced GA levels, over-expression of GA oxidase
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Vitamin A production by transgene overexpression – trans-kingdom gene transfer
Determining gene function based on mutagenesis – transgene tagging
Forward genetics – phenotype is selected and then the mutation in a specific locus is identified
WT siz1-2 siz1-3
Reverse genetics – mutation in a specific locus is identified and then the phenotype is determined
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Genetic transformation of plants – functional analysis by gene transfer and inheritance of transgene
Smith et al. (2010) Plant Biology
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Agrobacterium causes crown gall
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Agrobacterium T-DNA is integrated into the plant genomeTumorization - auxin and cytokinin biosynthesisTumor growthOpine biosynthesis
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Agrobacterium infection and integration processes
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Smith et al. (2010) Plant Biology
“Disarmed” T-DNA vector for plant genetic transformation – elimination of genes that cause tumor formation and growth, opine biosynthesis Binary system includes a vir gene plasmid for replication, infection and integration
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DNA delivery “vehicles” for transformation of plant cells