Morphogenetic Genes in the T-DNA of Ri Plasmids
Agrobacterium rhizogenes is responsible for the hairy root syndrome of dicotyledonous plants which consists in an abundant proliferation of roots at the wounded site of bacterial infection (Elliot, 1951). Hairy roots contain a portion (T-DNA) of a large bacterial plasmid (Ri plasmid), which directs growth and differentiation of the transformed plant cells (Chilton et al., 1982; Spanò et al-, 1982b; White et al., 1982; Willmitzer et al.,1982). Hairy roots grow very actively in vitro in the absence of hormones with a characteristic highly branched and plagiotropic pattern (David et al., 1984); they synthesize specific opines of which three major types have been so far identified, agropine, mannopine and cucumopine (Petit and Tempe., 1985), corresponding to different families of Ri plasmids (Costantino et al., 1981). Whole, fertile plants of different species have been regenerated from hairy root tissues in several laboratories (Chilton et al., 1982; Spanò et al., 1982a; Tepfer, 1984; Spanò et al., 1987).
KeywordsHairy Root Hairy Root Induction Transform Plant Cell Wounded Site Carrot Disc
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