References
Gamborg, O. L., R. A. Miller and K. Ojima. 1968. Exptl. Cell Res. 50:151-158.
Gresshorff, P. M. and C. H. Doy. 1972. Planta (Berlin) 107:161-170.
Nitsch, J. P. and C. Nitsch. 1969. Science 163:85-87.
Murashige, T. and F. Skoog. 1962. Physiol. Plantarum 15:473-479.
Sree Ramulu, K., M. Devreux, G. Ancora and U. Laneri. 1976. Z. Pflanzenzuchtg. 76:299-319.
Sree Ramulu, K., and M. Devreux Cyto-genetics of differentiation in tissue cultures of tomato.
The in vitro culture has been shown to be mutagenic when plant regeneration occurs via callus-phase, and
especially from prolonged cultures. From the results obtained with in vitro cultures of different organs of tomato
(Table 1), it appears that several factors condition the differentiation processes.
Age of the cultures
Stem explants: In diploid of L. peruvianum (S1S5) the calli in prolonged culture (about 1 year) exhibited a
greater number of polyploid plants (50%), half of them being tetraploids and the other half octoploids. In triploid
(S1S2,S4) the young calli (six months old) gave regeneration only to triploids, not to hexaploids. On the contrary, the
old calli (about 1 year old) and the very old calli (1-2 year old) gave regeneration respectively to 25% and 59%
hexaploids. Similarly, in the diploid hybrid of L. esculentum x L. peruvianum old calli (1-2 year old) gave
regeneration to a high frequency of tetraploids.
Anther culture: In diploid of L. peruvianum (S12S13), the prolonged culture of calli on GD1 medium resulted in
an increase in the level of ploidy of the cells and gave regeneration to 67% tetraploids.
Genotype
The S-genotypes of L. peruvianum responded differently with respect to callus induction and to organ
regeneration: 2 out of 6 genotypes from anther culture, and 3 out of 7 from stem explants gave regeneration. In
other genotypes only some callus was formed. Differences in callus growth were noted among the genotypes in
which regeneration was obtained. For instance,
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