B, plant tissue culture refers to under aseptic conditions, the plant stem tips, stem segments or leaves are cut into small pieces, and cultured in a special culture medium, so that it gradually develops into a complete plant through cell proliferation and differentiation. Tissue culture belongs to the category of asexual reproduction.

C, potatoes are propagated by tubers, and the reproduction of new individuals directly produced by the mother belongs to asexual reproduction, and C is wrong.

D. The main part of the embryo of a seed is developed from a fertilized egg, which is formed by combining sperm and eggs. Under suitable conditions, embryos can develop into complete plants. As you sow, you reap. D is correct.

So choose: D.