Effects of agrobacterial oncogenes in kidney vetch (Anthyllis vulneraria L.)

Kidney vetch seedlings were induced to form hairy roots by inoculating their mesocotyls with the wild-type strain 15834 of Agrobacterium rhizogenes or with the A. tumefaciens strain C58C1 containing a binary vector system (the pRiA4b as a helper and the vector pCB1346 bearing a pTiC58-derived isopentenyl transferase gene (ipt, cytokinin biosynthetic gene) under control of its native regulatory sequences). Transgenic lines of three distinct phenotypes were selected: (i) Typically, the pRi15834-transformed tissues were stabilized in vitro and maintained for long periods as aseptic, fast-growing, hormone-independent, plagiotropic hairy root cultures which never regenerated shoots and lost the ability to synthesize opines. Their genomic DNA contained both the TL- and the TR-DNA. (ii) One of the HR-lines transgenic for the T-DNA of pRi15834 (named 52AV34) started to regenerate spontaneously into teratomous shoots. The shoots were found to produce opines and both the TL and TR parts of T-DNA were found to be partly deleted and/or rearranged. They contained phytohormones in similar levels as those found in seed-born shoots. (iii) A practically identical morphogenic response as in the line 52AV34 was observed in the clone 27AV46. However, its shooty, dark-green, slow-growing teratomas were proven to be kanamycin-resistant, opine-producing, and double-transformed by the pRiA4b sequences and the ipt gene. They over-produced auxins as well as cytokinins (mainly indoleacetylaspartic acid and ribosides of zeatin and isopentenyladenine).