Figure 1.

Comparison of A. tumefaciens-induced crown galls on wild-type tomato (a and c) and Nr mutant (b and d) stems. a, Front view of a 3-week-old tumor developed on a wild-type plant showing the typical unorganized callus shape of a young crown gall and the epinastic response of the leaves both above and below the tumor. b, Front view of a 3-week-old tumor developed on the Nr mutant, characterized by a smooth surface and leaves in the normal orientation. Note that the lower half of the gall is protected by epidermis. c, Side view of a 2-month-old tumor on a wild-type stem with numerous adventitious roots (white spots) developed both above and below the crown gall (indicated with arrowheads). d, Side view of a 2-month-old tumor on the Nr mutant showing a fibrous hard gall and a stem almost free of adventitious roots. All photographs are at the same magnification (bars = 10 mm).