Question

Ti-plasmid naturally occurs in
A. Agrobacterium
B. Corynebacterium
C. Staphylococcus
D. Vibrio

Answer 1

Hint: It belongs to a genus of Gram-negative bacteria given by H. J. Conn which uses horizontal gene transfer in order to tumors in plants. It is most commonly known for its ability to transfer DNA between plants and it plays a major role in genetic engineering.

Complete answer:
A tumor-inducing plasmid or T which is in the shape of a circular plasmid present in the cells of the bacteria Agrobacterium tumefaciens and Agrobacterium rhizogenes. Those bacteria use the genes of the plasmid to transduce their genetic material and the desired genes in plants.

Additional Information: Plasmids are generally circular DNA molecules, although sometimes there are plasmids that are linear or made up of RNA. They can be found in single or multiple copies and can carry anywhere from half a dozen to several hundred genes. Plasmids can only multiply within a host cell. Most plasmids inhabit bacteria, and in fact, about 50% of bacteria found in nature contain one or more plasmids. These are also found in organisms such as fungi and yeast. The 2-micron yeast circle (discussed below) is a well-known example that has been modified for use as a cloning vector. Most plasmids are circular, made up of DNA, and much smaller than chromosomes. They are often responsible for resistance to several antibiotics, including penicillins.
So, the Correct answer is ‘Agrobacterium’.

Note: The range of host plasmids varies considerably. Some plasmids are limited to a few closely related bacteria; for example, plasmid F inhabits only E. coli and related enteric bacteria such as Shigella and Salmonella. Others have a wide range of guests; for example, the P family plasmids can live in hundreds of different species of bacteria. Although "P" is now often taken to mean "promiscuous," due to their unusually wide host range, these plasmids were originally named after Pseudomonas, the bacteria in which they were discovered.