Plant biotechnology Flashcards
Plat biotech
Breeding plants to improve quality, increase yields and reduce harmful characteristics in crops
Plant breeders able to introduce beneficial traits in plants more precisely
Plant tissue culture
Totipotency – a differentiated plant cell retains the genetic info required to generate a whole organism
Explant – sterile growth medium – callus – organ differentiation – root formation – plantlets generated – root and shoot formation – sterile culture of plants, micropropagation, mutants, GM plants
Growth medium:
Solid medium = agar
Carbon source = sucrose
Macronutrients = n, p etc
Micronutrients
Vitamins, co-factors
Hormones = auxin, kinetin
New plants and micropropagation
New plants (dip or hap) can be generated from single cells
Micropropagation by shoot meristem culture (mericloning) is very important in orchid propagation industry
Plant protoplasts
Plant protoplasts
Protoplasts formed after plant cells are treated with cell wall dissolving enzymes (cellulases)
Protoplasts can be fused to generate hybrid species with increased vigour
Cell suspension culture
Uniform suspension of cells in a liquid medium
Plant callus – liquid medium – agitate continuously – cells separate – sub culture cells
Arabidopsis
Small, weedy, annual member of brassicaeceae
Very small genome size (entire genome sequenced)
Easy to germinate, short period from seedling to fruiting – short life cycle (6 weeks), easy to grow
Self-fertile, lots of mutants
Genetic information of plants
T-DNA = transfer DNA Ti plasmid and bacteria
Viruses = small infection agent can only reproduce inside living cells
Electroporation = increases permeability of cell membrane
Microinjection = glass pipette injects a single cell
Gene gun = DNA on precious metals, blasted into plant cells
Crown gall tumour
Disease caused by bacterium – Agrobacterium tumefaciens - which enters the plant through wounds in roots or stems and stimulate the plant tissues to grow in a disorganised way, producing swollen galls
CGT and Ti plasmid
Tumour inducing plasmid is part of the genetic equipment the bacteria uses to transduce its genetic information to plants
Genetic transformation with T-DNA
Genetic transformation with T-DNA
a) T-DNA disarmed onc and O genes taken out = foreign gene inserted to give recombinant plasmid
b) Binary plasmid vector constructed and transferred into Agrobacterium
c) T-DNA integrated into plant genome = transgenic plant produced
d) Limited by species that can be infected
Electroporation
Increase permeability of plasma membrane cause by externally applied electric field
Method of introducing a substance into a cell (molecular probe, drug, piece of coding DNA)
Protoplasts in electric field take up DNA
Can be done w lots of different species but protoplast regeneration can be difficult
Direct introduction of DNA into plant cells
a) Gene gun = DNA on tiny golf or tungsten particles blasted into plant cells
b) Microinjection
c) Virus
Mutants
Very important in elucidating gene function in plant biochem, physiology and development
Mutagenesis brought about by chemical mutation, irradiation, insertional mutagenesis
GM plants and agriculture
Improved crop yield = e.g better use of fertiliser
Improved nutritional value = e.g more vitamins (golden rice w added vitamin A), fewer trans-fatty acids, more lysine
Herbicide resistance – controversial
Resistance to pests = insects, fungi, viruses
Growth under stressed conditions = high salt, drought
Better fruit ripening and shelf life
Control flowering and fruiting time
Other biotechnological aspects
Pharmaceuticals (pharming) e.g anti tumour drugs, insulin, edible vaccines/antigens
Bioplastic (biodegradable)
Oil, biofuel = source of energy in future (potential)
Phytoremediation = using plants to mitigate environmental problems
