Tissue Culture Types

Question 1

Adventitious Shoot Formation

Answer 1

• shoots that arise from places where buds do not normally form, such as roots, leaves, flowers, and stem internodes
• 2 types:

1. diploid plant regeneration
2. haploid and triploid regeneration

Question 2

Anther Culture

Answer 2

• also called haploid regeneration
• pollen grains that can develop into embryos
• a procedure for obtaining haploid plants from normally diploid plants
• want to produce haploid plants to allow crossing between species with different chromosome number
• used to create dihaploids (super easy way to get F1 hybrid inbred

Question 3

Axillary Shoot Formation

Answer 3

• axillary shoots form directly from existing meristems
• the initial explant is a shoot tip or stem piece (1, 2, or 3 nodes)
• the most stable form
• 2 types:

1. meristem culture
2. shoot culture

Question 4

Bioreactor

Answer 4

• are automated systems for production of callus
• can be used to produce: enzymes, medicines, natural flavors, colors
• but mainly done with fungal or bacterial cultures

Question 5

Callus Culture

Answer 5

• callus can be derived from any tissue explant
• callus = undifferenciated tissue
• uses: research, breeding, genetic transformation studies. callus cells can be used to produce enzymes, medicines, natural flavors, and colors
• 4 types:

1. stationary callus culture
2. suspension callus culture
3. bioreactors
4. protoplasts

Question 6

Cell Culture

Answer 6

• also called callus cultures (stationary)
• structures formed: callus
• explant source: any vegetative tissue
• uses: callus cultures are used for research, breeding, and genetic transformation studies. callus cells can be used to produce enzymes, medicines, natural flavors, and colors

Question 7

Direct Somatic Embryogenesis

Answer 7

• somatic embryos form right into tissues
• explant source: embryo, seedling or leaf. somatic embryos form directly from cells in the original explant
• uses:
  
  • can be used to regenerate copies of the original mother plant or recovery of plants that have been genetically transformed

Question 8

Embryo Culture

Answer 8

• type of seedling formation
• mature embryos germinate easily in tissue culture to form embryps
• almost any seed/embryo can be germinated in tissue culture
• used for:
  
  • research
  • to create understocks for micrografting
  • sometimes for propagation

Question 9

Embryo Rescue

Answer 9

• immature embryos are removed from the ovule before they abort
• primarily used in breeding to rescure embryos from interspecific crpsses
  
  • these crosses are initially successful and embryo forms but the endosperm does not
  • so this is replacing the missing endosperm with culture medium
• explant source: isolation of immature embryos
• uses:
  
  • primarily for breeding interspecific crosses. these crosses usually fail to set seed, but early embryo development can occur. embryos commplete their development in tissue culture

Question 10

Heterotrophic

Answer 10

• when an explant relies on a sugar source to produce new shoots

Question 11

Indirect Somatic Embryogenesis

Answer 11

• has to form a callus first
• the explant source: any plant part. somatic embryos form after explant is induced to form callus
• uses:
  
  • to regenerate clonal copies of the mother plant or genetically transformed plants
  • has the greatest potential for mass propagation through synthetic seeds

Question 12

Meristem Culture

Answer 12

• a procedure to eliminate diseases from plants
  
  • b/s meristem is usually disease free
• uses a very small piece of tissue from the shoot tip as the initial explant
  
  • including meristem dome and a few subtending leaf primordia
• regeneration method: type of axillary shoot formation
• structures formed: plantlet formation
• explant source: shoot tip less than 1 mm in size
• uses:
  
  • initially developed as a micropropagation system
  • but now mostly used for virus elimination

Question 13

Micrografting

Answer 13

• .an alternative to meristem culture
• small scion shoot tip usually grafted to a seedling understock
• for production of disease-free plants, studying grafting problems, propagation method, rejuvenation
• mainly used to send germplasm between countries

Question 14

Micropropagation

Answer 14

• is a form of tissue culture used to regenerate (propagate) new plants
• developmental stages:

1. Establishment: placing tissue into culture and having it initiate microshoots
2. Shoot multiplication: inducing multuple shoot production
3. Root formation: initiating roots on microcuttings
4. Acclimatization: gradually moving plants to open-air conditions

Question 15

Minitubers

Answer 15

• a speciality type of axillary shoot formation
• potato plants in culture can form minitubers at the end of small stolons
• minitubers can be produced in plants that naturally form tubers like potatoes and yam
• each minituber can be used as a propagule
• in tropics/subtropics, ave to speciality store the big tubers for a year till plant again, not economically feasiable so either do true seeds or minitubers
• these storage organs can be removed and used in the production of virus-free planting stock

Question 16

Nodal Cultures

Answer 16

• a type of axillary shoot formation
• long shoots are cut into single nodes and placed vertically in the medium
• axillary buds at each node elongate and grow in length. the pattern is repeated by again cutting into nodal segments at each subculture
• used with species with strong apical dominance - very species dependant

Question 17

Proembryo Masses

Answer 17

• .the mass of embryos that is formed during somatic embryogenesis

Question 18

Protoplast

Answer 18

• are isolated signle cells from which the cell wall has been removed by fungal enzymes
• take plant cell and remove cell walls
• used for:
  
  • basic research
  • breeding
• two protoplasts can fuse to form a single cell
  
  • the nuclei combine
  • form a single new genotype
  • this is a way to bypass natural sexual incompatibility
  • new cells form and shoots can be regenerated from the resultant cells

Question 19

Pseudocorms

Answer 19

• a type of speciality axillary shoot formation
• this is speciality for orchids
• the growing points of orchids in culture form pseudocorms
• pseudocorms can be subcultured topropagate orchids
• orchids in culture can continue to produce cluster of pseudocorms

Question 20

Somatic Embryogenesis

Answer 20

• embryos are induced to form vegetataive tissue
• form from a single cell in the explant
• lack endosperm or seed coats
• are often smaller and malformed cotyledons

Question 21

Stabilization

Answer 21

• cultures are considered stabilized when they begin to make new shoots that are ready to subculture

Question 22

Stages of Somatic Embryogenesis

Answer 22

1. induction
2. development
3. conversion
4. germination

• change media for each stage b/c requires different hormone levels

1. induction: trying to change cells ‘mission’ - reprogram cell to express embryonic DNA. usually initiate from a single cell. usually requires 2,4D
2. Development: enhanced by ABA, inhibited by 2,4D.
3. Conversion: prepares embryo for germination. can be aided by desiccation step.
4. Germination: usually proceeds normally but gibberellin can sometimes be used to enhance germination. after germination, plantlet is formed.

Question 23

Stool Shoot Culture

Answer 23

• a type of axillary shoot formation
• a shoot with several nodes is layered horizontally on the medium. lateral growing points form a thicket of small vertical growing shoots
• these “layers” may be subdivided at each subculture or the entire unit transferred to a new culture vessel when the medium is exhausted
• structures formed: plantlets
• often done because of apical dominance

Question 24

Suspension Culture

Answer 24

• called callus suspension culture
• structures formed: callus
• explant source: callus subcultured from stationary cultures
• suspension cultures are shaken constantly to perpetuate callus formation.
• uses: research, breeding, and genetic transformation studies. callus cells can be used to produce enzymes, medicines, natural flavors, and colors

Question 25

Synthetic Seed

Answer 25

• contains a somatic embryo or plantlet surrounded by an artifical polymer seed coat (a semi solid alganate solution)
• so lacks own seed coat or endosperm
• uses:
  
  • clonal propagation to replace traditional seeds
  • to replace hand ollinated hybrid seeds
  • carriers for beneficial microorganisms, pesticides, and growth regulatiors

Question 26

Tissue Culture

Answer 26

• the ability to establish and maintain plant organs (embryos, shoots, roots, and flowers) and plant tissues (cells, callus, and protoplasts) in aseptic (microbial free) culture
• types of tissue culture:

1. plantlet formation
2. seedlings formation
3. callus formation
4. somatic embryogenesis

Question 27

Shoot Culture

Answer 27

• the most common form of micropropagation
• uses a portion of the stem with one to several nodes
• 3 main types:

1. axillary branching
2. nodal cultures
3. stool shoots

• some speciality types:

1. pseudocorms
2. minitubers
3. micrografting

Question 28

Axillary Branching

Answer 28

• a type of axillary shoot formation
• the apical shoot tip os repressed and lateral shoots are stimulated to form a dense clump of shoots
• the clump is seperated into smaller clumps during subculture