Transcript Document

Lecture 11 &12
Virus resistant plants
Expression of dsRNase(RNaseIII)
• wheat engineered to express the E. coli gene for
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ribonuclease (RNase) III
most plant viruses have double-stranded RNA
a mutant of RNase III was used
the mutant enzyme able to bind to double-stranded
RNA
introduced into wheat, under the control of a corn
ubiquitin gene (Fig. 4), by micro- projectile
bombardment
transgenic plants resistance to infection by barley stripe
mosaic virus
Genetic construct used to transform wheat plants
with the gene for the mutant form of E. coli RNase
III. The construct includes the maize ubiquitin
promoter, first exon and intron in front of a mutant
form of E. coli RNase III and a transcription
terminator region from a nopaline synthase gene
Expression of antiviral proteins
• pokeweed (Phytolacca americana) -3 antiviral proteins in
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its cell wall
pokeweed antiviral protein PAPI-in spring leaves;
PAPII-in summer leaves; and PAP-S-in seeds
Both PAP and PAPII are ribosome-inactivating proteins
remove a specific adenine residue from the large
ribosomal RNA
pokeweed plants infected with viruses, either PAP or
PAPII is synthesized
PAP and PAP II are good candidates for developing
transgenic plants resistant to a broad spectrum of plant
viruses