The Flavr Savr Tomato

November 25, 2014Lu Tian

Flavr Savr Tomato

• The first FDA approved genetically modified food • Licensed in 1994• Ripening causes production of an enzyme Polygalacturonase

in a gradual increasing level, which is responsible for softening of the tomato and which becomes the cause of rottening

• Calgene introduced a gene in plant which synthesize a complementary mRNA to PG gene and inhibiting the synthesis of PG enzyme.

Antisense RNA

Antisense RNA (asRNA) is a single-stranded RNA that is complementary to a messenger RNA (mRNA) strand transcribed within a cell.

Put PG gene sequences in the reverse orientation into the vector

Transformation

Isolate the nuclei used for in vitro transcription

Isolate the RNA

Hybridize RNA

Measure PG activity

Lycopene determination

Result

PG gene suppression is the result of RNAi

Promoter antisense cDNA poly A addition signal

antisense oligonucleotidemRNA

-antisenseRNA complex

dsRNA

Binding of dsRNA-specific nuclease

cleavage

mRNA is cleaved!

Nuclease-ssRNA complexHybridizes to mRNA

sense

antisense

Southern blot Two linked T-DNAs

Left T-DNA, lanes 1 and 2 (primers 1 and 4);Right T-DNA, lanes 3 and 4 (primers 2 and 3); full insert, lanes 5 and 6 (primers 1 and 2); unique junction region, lanes 7 and 8 (primers 5 and 6).

Diagram of the sequenced 13,621-bp T-DNA insertion and flanking genomic regions. DNA probes (bars C and D) and primers (arrows 1–6) used for confirmation PCRs are indicated.

Northern blot

Result

• Flavr Savr locus contains two linked T-DNAs• siRNAs from transgenes accumulate in Flavr

Savr tomatoes.