Practice question

Laboratory plant transformation uses disarmed Ti plasmids retaining only essential transfer functions. Vir genes of Ti plasmid sense acetosyringone and produce nickase, chaperones, and secretion apparatus. Type IV secretion system encoded by virB operon plus coupling factor VirD4 forms trans-kingdom channel for nucleoprotein export. Host plant genes encoding attachment receptors, karyopherins, histones, and DNA repair enzymes mediate nuclear targeting and integration. Opine catabolism genes encode transporters and dehydrogenases allowing bacteria to utilize opines as nitrogen and carbon source in crown gall niche. This nutritional advantage is irrelevant on synthetic culture media, making it dispensable.