Pest Resistance In Transgenic Plants | Flavr Sarv Transgenic Tomatoes | Golden Rice

👉 NEET Biology Concept Material

👉 NEET Biology Examination 

👉 NEET Biology Tips

👉 NEET Biology Study Material 

Pest Resistance In Transgenic Plants - Protection Against Nematodes 

• Many nematodes (Round worms) live in plants and animals including human beings.
• A nematode Meloidogyne incognitia infects the roots of tobacco plants and causes a great reduction in yield.
• A novel strategy was coined by Fire and Mello in 1998 to prevent this infestation that was based on the process of RNA interference (RNAi).
• RNAi takes place in all eukaryotic organisms as a method of cellular defense.
• This method involves silencing of a specific mRNA.

• Using Agrobacterium vectors, nematode specific genes are introduced into the host plant (tobacco plant).
• The introduction of DNA was such that it produced both sense and anti - sense RNA in the host cells.
• These two RNAs being complementary to each other formed a dsRNA (double stranded RNA) that initiated RNAi.
• Different steps involved in making tobacco plant resis tant to nematode are briefly described below

1. Double - stranded RNAs are processed into approxi mately 21-23 nucleotide RNAs with two nucleotides,An RNase enzyme called Dicer cuts. dsRNA moelcules (from a virus, transposon, or through transformation) into small interfering RNAs (siRNAs).
2. Each siRNA complexes with ribonucleases (dis tinct from Dicer) to form an RNA - induced silencing complex (RISC).
3. The siRNA unwinds and RISC is activated.
4. The activated RISC targets complementary mRNA molecules.
5. The siRNA strands act as guides where the RISCs cut the transcripts in an area where the siRNA binds to the mRNA. This destroys the mRNA.
6. When mRNA of the parasite is destroyed no pro tein was synthesized. It resulted the death of the parasite ( nematode ) in the transgenic host.Thus the transgenic plant got itself protected from the parasite.

Flavr Sarv ' transgenic tomato

• (Post - Harvest Losses / Delayed Fruit Ripening)
• In 'Flavr Sarv ' transgenic tomato, expression of a native tomato gene has been blocked.
• This gene produces enzyme polygalacturonase which promotes softening of fruit.
• The production of this enzyme was reduced in the Flavr Sarv transgenic tomato.
• The non - availability of this en zyme prevents over - ripening because the enzyme is essential for degradation of cell walls.
• Thus fruit remains fresh for a longer period than the fruit of normal tomato variety.
• It retains flavour, has superior taste and higher quantity of total soluble solids.

Golden Rice

• Golden rice is a transgenic variety of rice (Oryza sativa) which contains good quantities of ß - carotene (provitamin A - inactive state of vitamin A).
• ß - carotene is a principal source of vitamin A.
• Since the grains (seeds) of the rice are yellow in colour due to B - carotene, the rice is commonly called golden rice.
• ß - carotene (provitamin A) is converted into vitamin A.
• Thus golden rice is rich in vitamin A.

• It is required by all individuals as it is present in retina of eyes.
• Deficiency of vitamin A causes night blindness and skin disorder.
• Since the contents of vitamin A are very low in rice, vitamin A is synthesised from B carotene which is precursor of vitamin A.
• Prof. Ingo Potrykus and Peter Beyer produced genetically engineered rice by introducing three genes associated with synthesis of carotene.
• The grains (seeds) of transgenic rice are rich in provitamin.

========================================

Mail- indiabiologymanishmevada@gmail.com

Subscribe and Follow For more knowledge of Biology

It is also helpful for MCAT ( Medical College Admission Test) united States, Australia, Canada and caribbean islands.

For Join With Me Mail Me 

Manish Mevada

M.Sc, M.Phil, B.Ed

THANK YOU.