Information related to RNAi and CRISPR

2. POST TRANCRIPTIONAL
GENE SILENCING IN
PLANTS
Menail Sajid, Department of Biotechnology, University of
Kotli

3. CONTENTS
• Introduction
• Types
• History
• RNAi and CRISPER
• PTGS in plants
• Why PTGS
• Applications
• Disadvantages, Conclusion and references

4. TRANSCRIPTION
• First step of gene expression
• DNA is copied into RNA
• Enzyme RNA polymerase

5. TRANSLATION
• Protein synthesis process.
• Genetic code carried by mRNA.
• Amino acid carrying tRNA.

6. Translation

7. POST TRANSCRIPTIONAL
• Modification or silencing during conversion of
immature mRNA into mature mRNA.

8. GENE SILENCING
• “Turning off” of a gene.
• Naturally occurring process.
• An important laboratory technique.
• Prevent expression of certain gene.

9. WHY THERE IS A NEED FOR ……..

10. TYPES OF GENE SILENCING
Post
transcrip
tional
Transcri
ptional

12. POST TRANSCRIPTIONAL GENE
SILENCING
• Also called RNA interference or RNAi.
• Results in down regulation of gene at RNA level.

13. METHODS USED FOR GENE
SILENCING
• Methods used for gene silencing are;
RNA
Interference
CRISPER

14. HISTORY
• In 1990, Jorgensen observed that introduction of transgenes homologous to
endogenous gene often resulted in plants with gene suppression/silencing.
• In 1995, Guo and Kemphues said that injection of either sense or anti-sense RNAs in
the germ line of C.elegans is equally effective at silencing homologues target genes.
• In 1998, Mello and Fire proved that combination of both sense and anti-sense RNA
is 10 times more effective than single stranded RNA.

15. RNA INTERFERENCE
• Biological process in which RNA molecule inhibit gene action.
• Also named co-suppression.
• Found in wide variety of organisms include mammals.

16. PROCEDURE
• Dicer, which cleaves long double-stranded RNA (dsRNA) molecules into short
double-stranded fragments of ~21 nucleotide siRNAs.

17. CONTINUE…
• Next RISC protein attach one copy of RNA piece cut by Dicer.
• It moves along the DNA molecule.
• If any matched sequence is found RISC act and cut that sequence out.

19. CRISPER

20. CONTINUE

21. IN PLANTS
• Gene silencing was first practiced on plants.
• Done by using RNAi method.
• Example of gene silencing is FLAVR SAVR tomato.
• It contain altered fruit ripening and enhanced fruit quality.
• It was obtained by silencing gene that codes for
polygalacturonase.

22. WHY??
• Reduce lignin in plant cell wall.
• Decrease browning in apple.
• Insect resistant crops.
• Quality enhanced crops.
• Alter or delay ripening of fruits.

23. APPLICATIONS
• Used in cell culture.
• Cancer treatment
• It has been used for applications in biotechnology particularly in engineering of food
plants that produce low level of natural plant toxins.
• Establishment of stable and heritable phenotype in plant stock like cotton seeds.
• It have applications in urology and andrology.
• It have clinical applications at molecular diagnostics.

24. DISADVANTAGES
• Damage to the integrity of normal tissues and organs.
• Can be toxic to the host.
• May cause severe immune responses.

25. GENE SILENCING AND
BIOTECHNOLOGY
• As biotechnology is to practices methods for benefit
of mankind, here in gene silencing we do practice the
Gene silencing method for human benefits.

26. CONCLUSION
• Besides all types of gene silencing RNA interference is the most important method
used for post transcriptional gene silencing. It is widely used in agriculture and now
in therapeutics for treatment of many diseases like cancer or hemophilia. Just cut out
the faulty gene instead of long term medication. Steps are being taken to make it
possible to treat diseases using this technology.

27. REFERENCES
• Redberry, Grace (2006). Gene silencing : new research. New York: Nova Science
Publishers. ISBN 9781594548321.
• ^ Jump up to:a b "Gene Silencing". National Center for Biotechnology Information. Retrieved 11
November 2013.
• ^ Jump up to:a b c d Hood E (March 2004). "RNAi: What's all the noise about gene
silencing?". Environmental Health Perspectives. 112 (4): A224–9. doi:10.1289/ehp.112-
a224. PMC 1241909. PMID 15033605.
• ^ Jump up to:a b c Mocellin S, Provenzano M (November 2004). "RNA interference: learning gene
knock-down from cell physiology". Journal of Translational Medicine. 2 (1): 39. doi:10.1186/1479-
5876-2-39. PMC 534783. PMID 15555080.
• ^ Jump up to:a b Kole R, Krainer AR, Altman S (February 2012). "RNA therapeutics: beyond RNA
interference and antisense oligonucleotides". Nature Reviews. Drug Discovery. 11(2): 125–
40. doi:10.1038/nrd3625. PMC 4743652. PMID 22262036.