ONTOGENIC ORIGIN OF ROOTS, AND BUDS NEWLY FORMED ON THEM, IN CHIMERAS OF PEAR AND APPLE

Thirteen pear varieties and two apple varieties, which happen to be periclinal chimeras for chlorophyll deficiency or anthocyanin pigmentation, were rooted under mist, together with their parent variety as control. Most were able to differentiate shoots from these roots so that their phenotype for chlorophyll or anthocyanin pigmentation could be established. None of these neoformed shoots showed a chimeral structure. Most of them appeared to carry the phenotype of the internal layer L III. In a few exceptional cases, the origin of the shoots was the L II layer. One root produced only one type of shoot (L III or L II type), so it can be assumed that dechimerisation happens at the root initiation step. This provides a method other than irradiation to ascertain possible chimeral structure and obtain homogeneous shoots.