The process of RNA interference (RNAi) was used in Tobacco plant to develop resistance against:
(c) Nematodes
Understanding RNA Interference (RNAi)
RNA interference (RNAi) is a natural biological process that occurs in eukaryotic cells. It is a mechanism of post-transcriptional gene silencing. Essentially, RNAi helps regulate gene expression by interfering with messenger RNA (mRNA) molecules.
- The process involves small RNA molecules, such as small interfering RNAs (siRNAs) and microRNAs (miRNAs).
- These small RNAs guide a protein complex called the RNA-induced silencing complex (RISC) to target specific mRNA molecules.
- RISC then cleaves or prevents the translation of the target mRNA, effectively silencing the gene from which the mRNA was transcribed.
RNAi plays roles in various cellular processes, including defense against viruses and regulation of gene expression.
RNAi for Plant Resistance
Biotechnology has leveraged the RNAi mechanism to develop resistance in plants against pests and pathogens. The principle involves introducing genes into the plant that produce double-stranded RNA (dsRNA) or precursor RNA molecules. These RNAs are designed to be complementary to essential genes in the pest or pathogen.
When the pest feeds on the genetically modified plant, it ingests these RNA molecules. Inside the pest's cells, the ingested RNA triggers the RNAi pathway, leading to the silencing of the pest's essential genes. This gene silencing disrupts vital processes in the pest, which can lead to reduced feeding, inhibited development, or even death, thereby conferring resistance to the plant.
RNAi in Tobacco Against Nematodes
One successful application of RNAi in developing plant resistance was demonstrated in tobacco plants against nematodes. Specifically, this technique was used to confer resistance against the root-knot nematode, Meloidogyne incognita. Root-knot nematodes are significant agricultural pests that damage plant roots, leading to reduced yield and plant health.
The strategy involved creating transgenic tobacco plants that expressed dsRNA complementary to specific genes essential for the survival or development of the root-knot nematode. When these nematodes fed on the roots of these transgenic tobacco plants, they ingested the dsRNA.
- The ingested dsRNA triggered the RNAi pathway within the nematode.
- This led to the silencing of the target nematode genes.
- Silencing these essential genes severely affected the nematode's ability to feed, develop, and reproduce.
As a result, the population of nematodes in the soil around the roots was significantly reduced, and the transgenic tobacco plants showed considerable resistance to nematode infestation and damage compared to non-transgenic plants.
Analyzing the Options
The question asks about the organism against which RNAi was used in Tobacco plants to develop resistance. Based on the well-known application of this technology in agriculture:
| Option | Organism | Relevance to Tobacco & RNAi |
|---|---|---|
| (a) Viruses | Viruses | RNAi is a natural defense mechanism in plants against viruses, and engineering plants for enhanced viral resistance using RNAi is possible, but the classical tobacco example for this specific application often refers to a different pest. |
| (b) Fungi | Fungi | RNAi can potentially be used against fungal pathogens, but it's not the most prominent or classical example associated with early RNAi application in tobacco for pest resistance in textbooks. |
| (c) Nematodes | Nematodes (specifically Root-knot nematodes) | This is a well-documented and classic example of using RNAi in tobacco plants (and other plants) to develop resistance against significant agricultural pests like Meloidogyne incognita. The mechanism involves targeting essential nematode genes via ingested dsRNA. |
| (d) Insects | Insects | RNAi technology is being researched and developed for insect pest control in plants, but the early, widely cited example in tobacco using RNAi for pest resistance specifically targeted nematodes. |
Therefore, the process of RNA interference was famously used in tobacco plants to develop resistance against Nematodes, specifically the root-knot nematode.
Conclusion
The application of RNA interference (RNAi) in tobacco plants was a significant development in agricultural biotechnology, particularly for creating resistance against parasitic nematodes like Meloidogyne incognita. This method proved effective in protecting the plant's roots from damage caused by these pests by silencing essential genes within the nematode.
Revision Table: Key RNAi Concepts
| Concept | Description | Role |
|---|---|---|
| RNA Interference (RNAi) | Biological process of gene silencing via RNA molecules. | Regulates gene expression, defense against viruses. |
| dsRNA | Double-stranded RNA. | Initiates the RNAi pathway; target for engineering resistance. |
| siRNA / miRNA | Small interfering RNA / microRNA. | Processed from dsRNA; guide RISC to target mRNA. |
| RISC complex | RNA-induced silencing complex. | Protein complex that binds siRNA/miRNA and cleaves/inhibits target mRNA. |
| Gene Silencing | Reduction or complete suppression of gene expression. | Desired outcome in RNAi-mediated pest control. |
Additional Information: Biotechnology in Plant Protection
Beyond RNAi for nematode resistance, biotechnology offers various strategies for protecting crops from pests and diseases:
- Bt crops: Plants genetically modified to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). These proteins are toxic to specific insect pests that feed on the plant.
- Herbicide tolerance: Developing plants that can withstand the application of specific herbicides, allowing farmers to control weeds without harming the crop.
- Viral resistance: Engineering plants to express parts of a virus genome, which can trigger plant defense mechanisms (including RNAi) and make the plant resistant to infection by that virus.
- Disease resistance genes: Introducing specific genes from resistant plant varieties or other organisms that confer resistance to bacterial or fungal diseases.
These biotechnological approaches aim to reduce the need for chemical pesticides, improve crop yields, and enhance food security.
Important Questions from Biotechnology and its Applications
Match List-I with List-II:
List-I List-II (A) Produces crystals of toxic insecticidal proteins (I) Meloidogyne incognita (B) Nematode which infects the roots of tobacco plant (II) Agrobacterium tumefaciens (C) Vector used to transfer the nematode-specific gene into the host plant (III) Bacillus thuringiensis (D) Plasmids used to produce insulin chains (IV) Escherichia coli Choose the correct answer from the options given below:
Identify the statements which hold true for transgenic animals.
(A) Transgenic animals can be used to study vaccine safety.
(B) Over 95% of transgenic animals are mice
(C) Transgenic animals cannot be used to study human diseases
(D) Transgenic animal possesses and express foreign gene
Choose the correct answer from the options given below:
Human protein α-1 antitrypsin is used to treat:
Match List-I with List-II:
List-I List-II (A) Dodo (I) Russia (B) Quagga (II) Australia (C) Thylacine (III) Mauritius (D) Stellar’s Sea cow (IV) Africa Choose the correct answer from the options given below:
Bacillus thuringiensis produces Bt toxin crystals, it does not kill the bacterium itself as the toxin is in the ______ in bacteria.
