REGENERATION OF TRANSGENIC PAPAYA PLANTS VIA SOMATIC EMBRYOGENESIS INDUCED BY AGROBACTERIUM-RHIZOGENES

An Agrobacterium rhizogenes-mediated procedure for transformation of p apaya (Carica papaya) was developed. Transgenic plants were obtained f rom somatic embryos that spontaneously formed at the base of transform ed roots, induced from leaf discs infected with A. rhizogenes. Transfo rmation was monitored by autonomous growth of roots and somatic embryo s, resistance to kanamycin, beta-glucuronidase activity (GUS), and Sou thern hybridization analysis. Over one-third of the infected leaf expl ants produced transformed roots with GUS activity, from which 10% spon taneously produced somatic embryos. Histological analysis of A. rhizog enes-transformed embryos showed that they have an altered symmetry bet ween the shoot apex and the root meristem when compared to somatic emb ryos induced with hormone treatment from control explants. Transgenic papaya plants containing A. rhizogenes rol genes were more sensitive t o auxins, developed wrinkled leaves, and grew slower than nontransform ed plants.