The reason why auxin can promote the development of fruits and the rooting of cuttings is that auxin can change the distribution of nutrients in plants, get more nutrients in the parts where auxin is rich, and form distribution centers. Auxin can induce the formation of seedless tomato because the ovary of tomato bud becomes the distribution center of nutrients after auxin treatment, and the nutrients produced by leaf photosynthesis are continuously transported to the ovary, and the ovary develops.