Callus from Lycopersicon esculentum x L. peruvianum interespecific hybrids cultured in vitro lost their morphogenetic abilities after two years. An attempt has been made to recover the organogenesis of those callus, using 5 x 5 and 3 x 3 diallelic combinations between indolacetic acid (IAA) and 6-benzyl-adenin (6-BA). Mineral salts and vitamins of the MS medium (Murashige & Skoog), were used, added with sucrose (3%) and agar (0.8%). Culture medium pH was kept at 5.5. The 5 x 5 diallelic treatments were incubated under the following conditions: day temperature = 25 ± 3°C; day length = 16 hours; light intensity = 600 lux. The 3 x 3 diallelic treatments were kept at the same conditions of daylight and temperature but at 2000 lux light intensity. Callus development and shoot formation were graded from 1 to 5, 30 days after inoculation, Shoot number and height were also evaluated. In the 5 x 5 diallelic experiment, it was observed a low number of differentiated plants. The best combinations for callus development have been 0.5, 2.5 and 5.0µM of IAA with 2.5µM of 6-BA, respectively. However in the 3 x 3 diallelic experiment, it was recorded a high frequency of shoot formation s and the most efficient treatments were the 25.0 and 50.0µM concentrations of 6-BA, without any auxin. It was also observed the influence of environmental condi-tions (mainly light intensity) on the process.
tissue culture; tomato; organogenesis; interspecific hybrid