Food Biotechnology (new)

Question 1

What mechanism is utilized in Flavr Savor Tomatoes?

Answer 1

Antisense technology

Question 2

What happens when tomatoes are picked green for transportation?

Answer 2

• these fruits are able to with stand transportation without bruising.
• At their destination the green fruits are forced ripe by exposure to ethylene gas (cosmetic colour change but… no flavor development).

Question 3

What is antisense technology?

Answer 3

: Antisense DNA technology isa method to inhibit or downregulate the production of a target protein by using antisense DNA or RNA molecules. An antisense sequence is a DNA or RNA that is perfectly complementary to the target nucleotide sequence present in the cell

Question 4

What are the various changes that fruits (tomatoes) go through when ripening?

Answer 4

1. Loss of chlorophyll which gives it a less green appearance
2. Pigment accumulation - fruit colour development
3. Change in cell wall culture - leads to softening
4. Change in organic acids and increase production of volatile chemicals - Flavours changes

Question 5

Softening in ripe fruits is associated with what?

Answer 5

Degradation of pectin by polygalacturonase (PG)

Question 6

What are the two methods normally utilized to delay fruit ripening?

Answer 6

1. Reducing the amount of ethylene produced
2. Reducing the amount of PG

Question 7

Discuss how Flavr Savor tomato was/is engineered.

Answer 7

• Engineered using antisense technology
• An antisense gene was constructed by reversing the sequence of the gene.
  -Transcription of the antisense gene produces a RNA which is complementary to the mRNA and so can form dsRNA.
• This led to decreased translation of the mRNA

Question 8

Discuss the methodology behind the engineering of the Flavr Savr tomato.

Answer 8

• the cDNA of the polygalacturonase (PG) gene was created
• 730 bp fragment was excised (containing a non coding region)
• The fragment was cloned into a plasmid. It was cloned in the reverse orientation behind the CaMV 35S promoter into pBIN19 and subsequently into pJR16A with Kanamycin resistance (selectable marker)
• The PG gene was delivered into cell via tissue culture by Agrobacterium - mediated transfer.