Figure 1. Embryoids formed from callus derived from a self-compatible plant in the first backcross generation between cultivated tomatoes and L. peruvianum.
We have developed the first backcross generation between the cultivated tomatoes of L. esculentum and a wild species, L. peruvianum (PI128644), by means of in vitro ovule culture. Some self-compativle B1F1 plants were found in the backcross generation (Imanishi, 1989). One of them, EP20, was used for the experiment of embryoid formation.. In tehe first stem, callus formation was conducted using young shoots from the top of the plant that was sub- cultured in a 200 ml flask with MS agar medium without phytohormone at 25-27 C under 16 hr. light illumination (2,500-3,000 lux). Callus was formed at 25 days on MS agar medium supplemented with 1 mg/l of NAA and BAP at the same condition of temperature and light. In the second step, callus cells, after being put through 850 um mesh, were cultured in suspension in 8E medium (Zapata et al., 1989) supplemented with 0.1 mg/l NAA at 25 C under a low light intensity for one week. In the last step, small masses of cells in size of 350-500 um were cultured in dark on MS agar medium supplemented with 2 mg/l ZR for about one month. As the result, although the number were few, embyoids were formed as shown if Fig. 1.
Figure 1. Embryoids formed from callus derived from a self-compatible plant
in the first backcross generation between cultivated tomatoes and L.
peruvianum.
Literature cited:
Imanishi, S. 1989 J. Breed. 39:L217-227.
Zapata, F.J., K.C. Sink and E.C. Cocking 1981 Plant Sci. Lett. 23:41-46.