Plant Biotechnology 7 Flashcards
Define plant technology
The application of laboratory-based techniques for plant propagation or genetic improvement
Define tissue culture
the culture of plant organs, tissues, cells or protoplasts on nutrient media under sterile conditions
Name 4 applications of plant tissue culture
Suspension cultures
Somatic hybridisation
Micropropagation
Production of transgenic plants
Define cell suspension culture
The growth of plant cells under sterile conditions in a liquid medium, with shaking.
Give two uses of cell suspension culture
Research
Commercial production
What is a protoplast?
Plant cell without a cell wall
What is a somatic hybridization?
Production of novel hybrids between sexually incompatible plant species
What is micropropagation?
Commercially important for propagating individual plant genotypes where other methods of propagation are difficult
What does a micropropagation start with?
an explant
Define totipotency
The ability of an individual cell to divide and form all parts of the mature organism
What does totipotency depend on?
Dedifferentiation
Redifferentiation
Describe the process of regeneration by organogenesis
Isolation of an explant under sterile conditions
Callus production on nutrient medium containing plant hormones (auxin and cytokinin
Organogenesis stage I: the generation of new shoots from the undifferentiated callus (promoted by cytokinin)
Organogenesis stage II: the generation of roots from the shoots (promoted by auxin)
What is somatic embryogenesis?
Development of embryos and whole plants directly from somatic cells
What is soma clonal variation?
Phenotypic variability between individual plants derived from plant tissue culture
What is an advantage of somaclonal variation?
Creation of additional genetic variability for plant improvement
What is an disadvantage of somaclonal variation?
Lack of uniformity is a problem in micropropagation for horticulture and forestry industries
How are transgenic plants produced?
Production of a DNA construct that harbours the gene of interest
Transformation of plant cells with the construct
Selection of transformed cells using a selectable marker
Regeneration of whole plants from transformed cells
What 4 things do you need to consider in a promoter?
Constitutive (on all the time throughout the plant)
Tissue-specific (e.g. only expressed in root hairs)
Developmentally regulated (e.g. activated during fruit ripening)
Inducible (only activated when a chemical treatment is applied)
Describe selectable markers
They are a way to identify which cells contain the gene of interest
Usually are antibiotic resistant genes to chemicals that are toxic to plants
What two ways can foreign DNA get into plant cells?
Naked DNA delivery systems
Natural delivery systems
How does Naked DNA get into the plant cells by particle bombardment?
Gold coats the DNA. These are used to fire at plant cells at a high velocity. Particles penetrate cell walls and membranes and the DNA is released and incorporated into the plant chromosomes
How does Naked DNA get into the plant cells by electroporation?
Use of a short high voltage electrical discharge to make the plasma membrane permeable to DNA
How do natural delivery systems work?
Use Agrobacterium tumefaciens
This is a plant pathogen that infects wound sites and produces tumours
It transfers a small segment of its DNA into the plant genome
The T DNA is on the TI plasmid
What can the genes do that the T DNA carry?
Induce uncontrolled cell division
Direct the synthesis of opines
Describe the structure of the Ti plasmid
Contains Vir region and the T DNA
T DNA has left and right border
Each border has 25bp repeat sequence after it
What are Vir genes needed for?
Transfer processes
Why may we remove the T DNA borders?
To replace them with genes we want to transfer into the plant using selectable markers
What is floral dipping?
Developing flowers are immersed in a suspension of Agrobacterium
What frequency does floral dipping occur at?
0.5%>
