Samenvatting Plant Biology - Inhoud Plant - Studeersnel (2024)

Vak

Universiteit

HAN University of Applied Sciences

Boek in lijstCampbell Biology

Geüpload door:

Reacties

Inhoud

• Plant Origin..................................................................................................
  • Origin of life..............................................................................................
  • 1 st cells......................................................................................................
    • Prokaryotic cells.....................................................................................
  • From prokaryotic to eukaryotic cells (Endosymbiose)...............................
  • Eukaryotes................................................................................................
  • Photosynthetic eukaryotic organism.........................................................
  • Larger organisms......................................................................................
  • Colonization of the land............................................................................
    • Non-vascular plants...............................................................................
  • Vascular Plants..........................................................................................
    • Carboniferous forest............................................................................
  • Emergence of seed plants......................................................................
  • Transition................................................................................................
  • Flowering plants(Angiosperms)...............................................................
  • Life cycle summary.................................................................................
  • Transition................................................................................................
  • Evolution of Grasses...............................................................................
  • Present....................................................................................................
• Plant transformation..................................................................................
  • Problem...................................................................................................
  • Solution...................................................................................................
  • Plant transformation...............................................................................
    • Agrobacterium infects plant tissue......................................................
    • Agrobacterium engineers the plant.....................................................
    • Agrobacterium Ti plasmid....................................................................
    • Transformation process........................................................................
    • Transfer T-DNA-strand..........................................................................
    • Type IV secretion mechanism..............................................................
    • VIR operon...........................................................................................
    • Integration of the T-DNA in the plant genome.....................................
  • Binary vector system..............................................................................
  • transformation........................................................................................ Advantages and Disadvantages in Agrobacterium-mediated
  • Other transformation techniques............................................................
    • Arabidopsis transformation..................................................................
    • Protoplast fusion..................................................................................
    • Micro injection of DNA in plant............................................................
    • Bombardment/Biolistics.......................................................................
  • How to know that your plant is transformed?.........................................
• Metabolism................................................................................................
  • Carbon assimilation: photosynthesis......................................................
    • Electron transport and Carbon assimilation.........................................
    • Light-dependent reactions...................................................................
    • The Calvin cycle...................................................................................
  • Sucrose synthesis...................................................................................
  • Photorespiration......................................................................................
  • C2, C3, C4 and CAM plants.....................................................................
    • Anatomy of C4 leaf compared to that of a C3-plant............................
    • C4 plants.............................................................................................
    • CAM plants...........................................................................................
    • C3, C4, Cam plants..............................................................................
    • C2 plants.............................................................................................
  • Sucrose synthesis and transport.............................................................
    • Movement of water and sucrose..........................................................
  • Carbon storage.......................................................................................
    • Starch synthesis..................................................................................
    • Starch degradation..............................................................................
• Plant interactions.......................................................................................
  • Fungi.......................................................................................................
  • Insects....................................................................................................
  • Nematodes.............................................................................................
  • Bacteria..................................................................................................
  • Viruses....................................................................................................
  • Parasitic plants........................................................................................
  • Nitrate reductase....................................................................................
  • Nitrogen storage.....................................................................................
  • Nitrogen-Fixing Bacteria: A Closer Look..................................................
    • Rhizobia...............................................................................................
  • Synthesis of the Nod-factor....................................................................
  • Two sets of genes for symbiosis (NOD and NIF genes)...........................
  • From N2 to NH3......................................................................................
• Environmental signals................................................................................
  • Seed germination....................................................................................
  • Seedling development............................................................................
    • Ethylene...............................................................................................
  • Triple response........................................................................................
  • Light and photoreceptors........................................................................
    • Two developmental pathways for seedlings........................................
    • Etioplasts versus chloroplasts..............................................................
    • Photomorphogenesis versus skotomorphogenesis..............................
  • Tropisms, Root and shoot growth............................................................
    • Root and shoot growth.........................................................................
  • Flowering, Photoperiodism, Circadian rhythms.......................................
    • Molecular control of vernalization........................................................
• Environmental stress.................................................................................
  • Light as stress.........................................................................................
    • The water-water cycle.........................................................................
    • Activation of xanthophyll cycle............................................................
    • Preventing photooxidative damage.....................................................
    • Low light can also be stressful: how to cope?......................................
    • UV-light................................................................................................
  • High temperature as stress.....................................................................
  • Water deficit as stress.............................................................................
    • ABA “the stress hormone”...................................................................
    • Compatible osmolytes (such as polyols)..............................................
    • LEA (late embryogenesis abundant) proteins......................................
    • Aquaporins: facilitate water transport between cells..........................

CAM plants........................................................................................... 99Xerophyte.......................................................................................... 100Salt as stress......................................................................................... 101Water deficit response and additional adaptations............................ 102Cold as a stress..................................................................................... 104Cold acclimation................................................................................ 105Anaerobic stress................................................................................... 105.............................................................................................................. 105Oxidative stress.................................................................................... 108.............................................................................................................. 108Anthocyanins........................................................................................... 110Anthocyanins in stress response....................................................... 113Summary................................................................................................. 115

Plant Origin..................................................................................................

Origin of life..............................................................................................

 13 BYA: Big Bang 5BYA: Solar nebula

• Earth formation
• High temperature- High CO2 level

Eukaryotes................................................................................................

Photosynthetic eukaryotic organism.........................................................

 Three clades of protists Life cycle of green algae: Chlamydomonas ( Asexual and Sexual reproduction)

Larger organisms......................................................................................

570 MYA

 Drastic changes

• Rising oxygen levels
• Formation of an ozone layer
• Evolution rate accelerated
• More diversity = Cambrian Explosion Plants were about to move to the land...

Colonization of the land............................................................................

New features:  Ability to survive desiccation - Cuticle(extracellular hydrophobic layer that covers the aerial epidermis_ - Stomata - Sporoporellin (protection for spores) - Rhizoids(protuberances that extend from the lower epidermal cells of bryophytes and algae)

Non-vascular plants...............................................................................

 Bryophytes

• Mosses
• Liverworts Large gametophyte
• Haploid
• Hydroids (primitive vascular cells)Life cycle of mosses

Carboniferous forest

 CO2 levels very low Temperature drops Widespread glacier formation Supercontinent: Pangea- Drier climate Emergence of the seed plants(250-145 MYA)

Emergence of seed plants

 New Features

• Heterospory
• mega and micro sporophyll(Zaad en eicel) -> Drought
• Airborne pollen grains
• Seed coat Cold
• Needles as leavesLife cycle of Gymnosperms

Transition

Landmass broke up into the continents

• Different climates
• Insect diversification Plants attracted insects for pollination
• Flowering plants

Flowering plants(Angiosperms)

145 – 65 MYA

Coevolution: Insect diversification in Cretaceous - Beetles, flies, mosquitoes, butterflies: More primitive flowers - Wasps, bees: More evolved flowers - Ants: Involved in seed dispersalBiotic interactions: Pollen and seed dispersal by animals  New features: - Flower - Nectar

Life cycle summary

Transition................................................................................................

65 MYA

• Meteorite impact
• Disappearance of dinosaurs
• Emergence of mammals

Evolution of Grasses

Tertiary 65 – 2 MYA  New features - Coevolution with grazing mammals - Low apical meristem - Wind pollination - Drought: C4 and CAM photosynthesis

Present

Holocene 12 years ago – present

• Human influence on plants
• Domestication of plants
• Plant breeding
• Molecular plant breeding

Plant transformation

Problem

Classical plant breeding is slow and imprecise - Repeated generations of selection and crossing needed - Many years - Only transfer between plants that can sexually hybridize - Relatively small gene pool - Undesirable genes transferred (linkage drag) - Several generations to cross out of the plants

Solution

Molecular Plant Breeding - MAS: (Molecular) Marker Assisted Selection - WGS: Whole Genome Sequencing - Genetic Modification

Agrobacterium infects plant tissue......................................................

• Agrobacterium transfers some of its own DNA into the plant cells
• The transferred DNA encodes enzymes that:
  • are involved in the synthesis of auxin and cytokinin, which promote cell division
  • are needed to synthesize opines (these are not encoded in plant genomes)Tumor inducing plasmid
• Ti plasmidRoot inducing plasmid
• Ri plasmid

Agrobacterium Ti plasmid....................................................................

• The virulence (vir) genes (located on seven operons: virA to virG) encode proteins required to mediate the T-DNA transfer
• The T-DNA is bordered by 24-bp DNA sequences, present on the left and right border of the T-DNA
• Operon: functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter.

Transformation process........................................................................

• When a plant is wounded, it will produce acetosyringone.
• The bacteria will detect acetosyringone through proteins encoded by vir A code for an autokinase.
• VirG: functions as an operon.
• To transfer the T-DNA into the plant cell, A. tumefaciens uses a type IV secretion mechanism,

involving the production of a T-pilus. When acetosyringone and othersubstances are detected, a signal transduction event activates theexpression of 11 genes within the VirB operon which are responsiblefor the formation of the T-pilus

Transfer T-DNA-strand..........................................................................

LB and RB contain manyrepeats.9steps for Agrobacterium-mediated T-DNA transfer to the plant

1. The plant releases wound signal compounds, such as acetosyringone
2. Agrobacteria attach to plant cell surfaces at wound sites
3. Bacteria attach to plant cell surfaces at wound sites
4. VirA with signal bound activates virG
5. Activated virG turns on other vir genes, including vir D and E
6. Vir D cuts at the right border of the Ti plasmid and binds to the 5’-end

VIR operon...........................................................................................

Integration of the T-DNA in the plant genome.....................................

T-DNA delivery:Mechanism evolved form bacterial conjugation:Inside the plant cell, the T-DNA is target to the nucleus by the bound VirDand VirE proteins, which carry amino acids sequences recognized by themachinery that imports proteins into the nucleus.Very short regions of hom*ology between T-DNA and plant DNAT-DNA in the host cell relies on multiple interactions with Agrobacteriumand host cell proteins, taking advantage of several host cell pathways toensure the T-DNA nuclear import and integration into the host genome.Both VirD2 and the single-stranded DNA binding protein VirE2—whichpackages T-DNA into a helical nucleoprotein complex, termed the transfer(T) complex— can interact, directly or indirectly, with host factors to allownuclear import of the T-complex. This process likely occurs in a polarmanner such that VirD2 directs the T-DNA to the nuclear pore while VirEfacilitates the passage of the entire T-complex through the pore via theimportin -dependent nuclear import pathway. Inside the nucleus, the T-complex is proteolytically uncoated from its associated bacterial and hostproteins, presumably by interacting with the host ubiquitin/proteasomesystem (UPS). Then, the single-stranded T-DNA most likely is converted to

a double stranded form and integrated into the plant genome by the hostDNA repair machinery.

Binary vector system..............................................................................

 Biotechnologists have exploited the natural transfer of DNA from Agrobacterium A system was developed to introduce any new piece of DNA into plant cells without causing tumors This was achieved by the creation of a binary vector system

• The vir genes are separated from the T-DNA components of the Ti creating two plasmids: - a helper plasmid with the vir genes - a plasmid containing engineered T-DNA
• The genes encoding enzymes of opine and auxin and cytokinin biosynthesis are deleted

transformation........................................................................................ Advantages and Disadvantages in Agrobacterium-mediated

mediated

transformation

Advantages Simple and cheap DNA that is transferred has defined ends Transgene can be linked to transformation marker Higher frequency of stable transformation On average, 1-2 T-DNA inserts in the DNA (=> lower incidence ofsilencing) Possibility to transfer long stretches of T-DNA (>150 kb)