Complex sentence: Crown gall disease and hairy root disease are closely related in terms of pTi and T-DNA insertion; however, the difference between the two is related to the amount and type of phytohormones that their respective T-DNA genes produce.
Split into simpler sentences: Crown gall disease and hairy root disease are closely related in terms of pTi and T-DNA insertion. The difference between the two is related to the amount and type of phytohormones that their respective T-DNA genes produce.