Plant Biotechnology

Question 1

What is conventional breeding?

Answer 1

process of introducing a desired trait into a plant by cross-fertilization, then selection, then a process termed ‘backcrossing’ to yield a genetically ‘stable’ cultivar.

Question 2

What is the aim of conventional breeding?

Answer 2

Aim is to transfer the trait and then to remove unwanted characters by selection and backcrossing.

Question 3

What is conventional breeding an essential technique for?

What’s the problem?

Answer 3

essential technique to generate new crop varieties.

- takes many breeding cycles to achieve genetic stability – tedious and painstakingly long process.

Question 4

What is conventional breeding an essential technique for?

What’s the problem?

Answer 4

essential technique to generate new crop varieties.

- takes many breeding cycles to achieve genetic stability – tedious and painstakingly long process.

Question 5

How does conventional breeding work?

Answer 5

Genes moved from one species or ‘type’ to another by recurrent backcrossing of hybrid to a parent - isolating (separating out) certain characteristics

Question 6

What is backcrossing?

Answer 6

When F1 individuals are crossed with one of the two parents from which they were derived, then such a cross is called a back cross. In such back crosses, when F1 is back crossed with the parent having dominant characters (phenotype), no recessive individuals are obtained

Question 7

In conventional breeding, how can the number of backcrosses required be significantly reduced?

Answer 7

Marker Assisted Backcrossing
incorporate a major gene from an agronomically inferior source (the donor parent) into an elite cultivar or breeding line (the recurrent parent).

Question 8

What is the
a) donor
b) recurrent
parent

Answer 8

transfer a desired trait such as a transgene from one variety (donor parent, DP) into the favored genetic background of another (recurrent parent, RP)
Donor : parent with the desired trait, may not perform as well as an elite variety in other areas.
Recurrent : usually performs well in all other areas

Question 9

What is linkage drag and how do we minimise it?

Answer 9

One genetic feature though of backcross breeding - reduction in fitness in a cultivar due to deleterious genes introduced along with the beneficial gene during backcrossing.

Question 10

How can we minimise linkage drag?

Answer 10

Marker- assisted backcrossing - precise and an effective method to introgress a single locus controlling a trait of interest while retaining the essential characteristics

Question 11

What is marker-assisted backcrossing?

Answer 11

process of using markers to select for target loci, minimize the length of the donor segment containing a target locus and/or accelerate the recovery of the RP genome during backcrossing

Question 12

What is introgression?

Answer 12

is the movement of a gene (gene flow) from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species.

Question 13

What is Chemical or Radiation Mutation Breeding?

Answer 13

process of exposing seeds to chemicals or radiation in order to generate mutants with desirable traits to be bred with other cultivars

Question 14

Essentially, what occurs with Chemical or Radiation Mutation Breeding

Answer 14

Plant with desired trait (produced via mutation) x cultivar, transfer the trait and then to remove unwanted characters by selection and backcrossing.

Question 15

What is Genetic Modification Breeding (GM)?

Answer 15

GM is a molecular technology and a form of the genetic engineering process. It involves inserting DNA, responsible for a desirable trait, directly into the plant’s genome (Transformation)

Question 16

What is required in Genetic Modification Breeding to ensure that the new gene isn’t affecting other genes already present in the plant?

Answer 16

Selection - growth condition that allows for the selective propagation of genetically marked cells
Screening - growth condition where both mutant and wild type are able to grow but can be distinguished phenotypically

Question 17

Is selection and backcrossing necessary for Genetic Modification Breeding?

Answer 17

Selection and backcrossing not necessary as technique is highly specific, but in practice is relatively common.

Question 18

Give an example of genetic engineering in nature

Answer 18

Agrobacterium tumifaciens - causes crown gall disease in a wide range of dicotyledonous plants
Bacteria infect plant through site of injury
and transfer a Tumour Inducing (Ti) plasmid of DNA.
relatively small (12-24 kb) region of the Ti plasmid, called the transfer DNA (T-DNA), is integrated into a host plant chromosome during the infection process.
Ti plasmid induces a tumour in the host plant which then produces amino acids (opines)
Bacteria utilize these amino acids (nopaline and octopine) as a source of carbon and nitrogen.

Question 19

How can we use agrobacterium tumifaciens for genetic engineering?

Answer 19

• A. tumefaciens can be modified to allow foreign genes to be incorporated into the genome of plant cells
• insert DNA wish to transfer into plasmid T-DNA
• remove disease causing genes (hormones and opines) and disease will not occur

Question 20

What is the basis of agrobacterium tumefaciens genetic engineering?

Answer 20

A. tumefaciens can be modified to allow foreign genes to be incorporated into the genome of plant cells

Question 21

Transgenic Plant definition

Answer 21

Transgenic plants are plants that have been genetically engineered, a breeding approach that uses recombinant DNA techniques to create plants with new characteristics

Question 22

What is the gene gun method? (biolistic method)

Answer 22

• propelling DNA-coated colloidal gold microprojectiles toward the tissue surface.
• Gas-accelerated particles penetrate into deeper layers based on adjustment of the discharge pressure.
• particles penetrate into the cytosol and cell nucleus, the efficacy of DNA transduction is substantially higher than that of other approaches and therefore substantially reduced doses of DNA plasmid are required

Question 23

What type of plants does the agrobacterium tumefaciens genetic engineering target?

Answer 23

Dicots - infection

Question 24

What does the gene gun method allow for?

Answer 24

Gene gun allows genetic modification of monocots, as Agribacterium tumifaciens infection mostly limited to dicots.

Question 25

What is often the target of biolistic transformation (gene gun)?

Answer 25

Scutellum of seed (The cotyledon in monocots is represented by a structure called the “scutellum” and is an outgrowth of the embryo)
Callus cells also common

Question 26

Genetic Modification Breeding in a nutshell

Answer 26

plant with desired gene produced via gene vector (agrobacterium) -> cultivar B and gives plant with desired gene

Question 27

List the two major transformation methods in biotechnology

Answer 27

• gene gun method

- agrobacterium tumefaciens

Question 28

Give examples of crops that can use agrobacterium as their gene vector

Answer 28

Potato, Tomato, Soybean, Cotton

Question 29

List the minor transformation methods that can also be used

Answer 29

Protoplast mediated (introduce a single kind of foreign DNA fragment containing homologous DNA sequences to the host DNA)
Virus mediated transformation
Microinjection / silicon carbide fibres
Transposons (Transposable elements (TEs), also known as “jumping genes,” are DNA sequences that move from one location on the genome to another)

Question 30

What is genetic transformation?

Answer 30

genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane

Question 31

What is Genetic Editing Breeding (GM)

Answer 31

GE is a new biological technology that allows precise modification of the genome.
plant w/ desired trait prod via genetic editing -> cultivar

Question 32

What is the most common tool used for genome editing?

Answer 32

CRISPR–Cas9 (CRISPR) is the most common tool in genome editing. GE technology works when “molecular scissors” cut a location in the genome with precision.
Scientists can then insert (new genes), remove genes or edit the part of the genome to introduce a desirable trait.

Question 33

Gene editing vs Gene modification

Answer 33

• while new gene insertion is random with GM, GE technology allows precise insertion of the desired gene.
• no foreign DNA in the GE plant’s genome. As a result, plants that have been modified with GE technology are indistinguishable from the plants that are altered through conventional breeding or “naturally occurring” plants. Because of this, some even argue that GE plants aren’t even GMOs.(gen modified organisms)

Question 34

What does CRIPSR mean?

Answer 34

Clustered regularly interspaced short palindromic repeats

Question 35

What is the CRISPR/Cas system?

Answer 35

bacterial immune system that confers resistance to foreign genetic elements (plasmids and phages) that provides a form of acquired immunity.
Recognise and cut exogenous DNA

Question 36

How is this CRISPR/CAS system used to edit genomes?

Answer 36

Simple version of this system is modified - existing genes to be removed/and or new ones added

Question 37

Describe the process of growing regenerated plant with new gene using transformation

Answer 37

1) agrobacterium + gene gun method -> transformed plant cell
2) Profileration of transformed cells (Callus formation) - cell expansion and cell division of the cells of the explants. During the formation of callus tissue, the explants lose its original characteristic
3) Shoot regeneration
4) Regenerated plant with new trait

Question 38

What is plant tissue culture and why is it significant to genetic engineering

Answer 38

Cells or small pieces of living tissue (explants) are isolated from a plant and grown aseptically on a suitable nutrient medium.

• It makes genetic engineering possible.
• It allows material to be bulked up for plant breeding.
• It allows genotypes to be cloned for sale (clonal propagation).
• It is used for in vitro conservation.

Question 39

What is totipotency?

Answer 39

potential of individual plant cells to develop into complex multi-cellular plants – all plants cells are ‘stem cells.’

Question 40

What is regeneration?

Answer 40

Most plant species can be induced to form callus in culture and to differentiate into whole plants.

Question 41

Summary of tissue culture

Answer 41

cell or explant -> nutrient media/growth regulators, callus tissue (mass of cells) -> nutrient media growth regulators -> differentiated plant tissue

Question 42

How can tissue cultures be induced into producing roots and shoots? (inducing organogenesis)

Answer 42

adding growth regulators (auxins, gibberellins, cytokinins, abscisic acid (ABA) and ethylene)

Question 43

What does a high auxin to cytokinins ratio mean?

Answer 43

root formation

Question 44

What does a low auxin to cytokinins ratio mean?

Answer 44

shoot formation

Question 45

What does an intermediate ratio of auxins and cytokinins mean?

Answer 45

favours callus formation

if none then no growth

Question 46

What are the different types of breeding in genetic engineering?

Answer 46

1) Conventional Breeding
2) Chemical or Radiation Mutation Breeding
3) Genetic Modification Breeding
4) Genetic Editing Breeding