summary plant biotech lectures

PLANT BIOTECHNOLOGY
GEN20306
Contents
Lecture 1 tissue culture and plant transformation ...................................................................... 1
Lecture 2 plant transformation: vectors and verification ........................................................... 13
Lecture 3 GMOs and beyond ................................................................................................... 23
Lecture 4 pests and diseases .................................................................................................. 30




Lecture 1 tissue culture and plant transformation
Plant genomes, organization and gene expression:

- Genomic DNA
- Gene structure
- Gene expression
- Regulation of gene expression
-Chromatin
-Transcription
-Translation
-Post-translational modification

, - Targeting gene expression
- tissue specific
- organel specific



Plant genome:

- 3 genomes in plants:
▪ Nuclear
▪ Mitochondrial
▪ Chloroplast
- Nuclear genome arranged in chromosomes
- Gametes → n chromosomes
- Somatic cells → 2n chromosomes
- X = 1 haploid genome equivalent
- Diploids → n = x
- Tetraploids → n = 2x


DNA in organelles:




Mitochondrial and chloroplast genomes:

Chloroplast:

- ~120-160 kb
- ~120-140 genes
- Circular
- Multiple copies

Mitochondrial:

- ~200-2500 kb
- Largely non-coding, 50-100 genes
- Multicellular



Nuclear genome structure:

,Euchromatin:

- Open structure
- Largely coding
- Transcribed
- Relatively low methylation

Heterochromatin:

- Dense, tightly packed
- Largely repetitive
- Many transposons
- High methylation
- Around centromere/telomeres



Coding vs non coding DNA

Coding: transcribed part of the genome (often encoding for a protein):

- Genes (mRNAs) (in higher plants ~30,000-60,000)
- t(transfer)RNAs
- r(ribosomal) RNAs (often repeats)
- mi(micro)RNAs

Non-coding: → all else:

- intergenic
- non-transcribed pseudogenes
- silenced/mutated (retro)transposons
- Heterochromatic repetitive DNA

Gene

, mRNA splicing




Gene expression

- Transcription
▪ Tissue specific
▪ Stage specific
▪ Stimulus responsive
- Followed by: translation
- And sometimes: post translational modifications



Regulation of gene expression: chromatin

Euchromatin:

- Open structure
- Gene dense (Arabidopsis 1 gene/5 kb)
- Methylated in patches
- Variation in methylation/chromatin modification
- Promoter methylation reduces or inhibits transcription
- Methylation of transcription unit has no effect on transcription