Select the CORRECT combination of genetic components that are essential for the transfer of TDNA segment from Agrobacterium tumefaciens to plant cells.a)Border repeat sequences and oncogenesb)Border repeat sequences and vir genesc)Opine biosynthetic genes and vir genesd)Opine biosynthetic genes and oncogenesCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

Border repeat sequences and vir genes are the correct combination of genetic components that are essential for the transfer of T-DNA segment from Agrobacterium tumefaciens to plant cells.

Explanation:

1. Border repeat sequences:
- The border repeat sequences are short DNA sequences found at the ends of the T-DNA segment in the Ti (tumor-inducing) plasmid of Agrobacterium tumefaciens.
- These sequences are recognized by the Agrobacterium's VirD2 endonuclease, which cleaves the T-DNA at these sites.
- The border repeat sequences play a crucial role in the transfer of the T-DNA from Agrobacterium to the plant cell.

2. Vir genes:
- The vir genes are a set of genes found in the Ti plasmid of Agrobacterium tumefaciens.
- These genes are responsible for the transfer and integration of the T-DNA into the plant genome.
- The vir genes encode proteins that form a type IV secretion system, which is used by Agrobacterium to inject the T-DNA into the plant cell.
- These proteins also help in the formation of a T-DNA transfer complex that transports the T-DNA from the bacterium to the plant cell.

3. Opine biosynthetic genes and oncogenes:
- Opine biosynthetic genes and oncogenes are not essential for the transfer of the T-DNA from Agrobacterium to plant cells.
- Opine biosynthetic genes are responsible for the synthesis of opines, which are unique amino acid derivatives that are produced by transformed plant cells and can be used as a nutrient source by Agrobacterium.
- Oncogenes, on the other hand, are genes that can induce tumor formation in plant cells when transferred by Agrobacterium.
- While these genes are important for the pathogenicity of Agrobacterium, they are not directly involved in the transfer of the T-DNA from the bacterium to the plant cell.

In conclusion, the correct combination of genetic components that are essential for the transfer of the T-DNA segment from Agrobacterium tumefaciens to plant cells is the border repeat sequences and vir genes. These components play crucial roles in the recognition, cleavage, transfer, and integration of the T-DNA into the plant genome.

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