Potato blight causes potato plants to shrivel and rot. The disease is caused by the pathogen Phytophthora infestans, infamous for its role in Ireland's Great Potato Famine in the mid-1840s. The disease can devastate crops during wet weather, sometimes leading to total crop loss. Researchers aim to use recombinant DNA methods to transfer blight resistance genes from resistant varieties into susceptible varieties of potato. Explain how restriction endonucleases and DNA ligase could be used to insert a potato blight resistance gene into a plasmid.

Verified step by step guidance

1. Identify and isolate the gene responsible for blight resistance in a potato variety that is naturally resistant to Phytophthora infestans. This gene will be the segment of DNA that needs to be inserted into the susceptible potato variety.
2. Use restriction endonucleases to cut the DNA at specific recognition sites. These enzymes act as molecular scissors to cut both the DNA containing the blight resistance gene and the plasmid DNA at specific sequences, creating sticky ends or blunt ends.
3. Ensure that the restriction endonuclease used on the plasmid DNA is the same or compatible with the one used on the blight resistance gene. This compatibility is crucial for the next step, as it allows the ends of the DNA fragments to match up, facilitating the insertion of the blight resistance gene into the plasmid.
4. Mix the cut plasmid with the isolated blight resistance gene. The sticky or blunt ends of the plasmid DNA will pair with the complementary ends of the blight resistance gene, allowing them to align and attach to each other.
5. Use DNA ligase to seal the nicks in the sugar-phosphate backbone of the DNA, effectively 'gluing' the blight resistance gene into the plasmid. This recombination results in a recombinant plasmid that now carries the blight resistance gene.