Question

Crown gall disease in plants is caused by:

• A. Ti-plasmid
• B. Pi-plasmid
• C. mycoplasma
• D. virus

Answer 1

The Correct Option is A

Crown gall is caused by Agrobacterium radiobacter Pv tumefaciens. Tumor inducing factor is contained in its plasmid (Ti-plasmid). The plasmids in non-gall forming strains lack the tumor inducing factor. Plasmids of A. radiobacter carry genes for production of a bacteriocin. This bacieriocin is highly effective against many pathogenic strains of the pathovar tumefaciens. The bacteriocin producing strains have been used for control of crown gall. Mycoplasma are prokaryotic cell wall less organisms. They causes Witches broom's of legumes. Viruses are obligate parasites made up of nucleoprotein. They cause many diseases like AIDS Tobacco mosaic disease of tobacco etc.