Abstract

Genetic tumors are neoplastic growths that arise spontaneously in particular genotypes in plants. In the present study, we observed the occurrence of tumors in interspecific hybrids between Solanum lycopersicum L. and Solanum habrochaites S. Knapp and D. M. Spooner. The hybridity of these plants was confirmed based on morphological characteristics, flow cytometry and random amplified polymorphic DNA analysis. Hybrids formed tumors when the plants were grown in a growth chamber. These tumors were formed most frequently on leaves, but also on cotyledons, stems and petioles. When hybrid plants bearing tumors were transferred to a greenhouse, the tumors disappeared and necrotic brown spots were visible in the positions where tumors existed previously. Further analyses indicated that tumors were never formed in the greenhouse. These results suggest that environmental conditions influenced tumorigenesis in hybrids raised from S. lycopersicum × S. habrochaites crosses. In addition, when stem segments of hybrids were cultured in vitro on plant growth regulator-free medium, tumors and shoot formation were induced. Thus, hybrids between S. lycopersicum × S. habrochaites provide an excellent experimental system to study plant tumorigenesis and to understand cell division and differentiation.

Key words: Environmental condition, growth abnormality, interspecific cross, tomato, tissue culture, tumor.

Abbreviation

Frs, Frosty spot; RAPD, random amplified polymorphic DNA.