Articles
CLONAL PROPAGATION, FLOWERING AND FRUITING OF TOMATO IN VITRO
No off-type plants were observed among greenhouse-grown plants arised from micropropagated plantlets A full route from the initiation of flower raceme to the formation of mature fruits has been reproduced in vitro. Tomato micropropagation was communicated to be initiated from seedlings or young plants (Kartha, et al, 1977; Polevaya, et al, 1988) The possibility of micropropagation initiating from adult fruiting tomato plants was studied in our work.
Tomato (Lycopersicon esculentum Mill., indeterminate F1- hybrid Alena) plants grown in a plastic greenhouse were used as a source of initial explants when more than 70% of the yield was harvested.
Lateral shoots (10–15 cm) were excised and treated for 5 sec with 70% ethanol and for 10 min with 0,1 % HgCl2 + 0,1 % saponine and washed 4 times with sterile water Explants with one node each were planted in test tubes (20 x 200 mm) on agar medium with mineral salts (MS or B5), sucrose, thiamine and IAA and cultured with 16 h of light per day and 23/18° C At the end of subculture (35–40 days) the plantlets were dissected into explants with apical and lateral meristems and used for the following subcultures.
The number of plantlets increased very slowly during the first 3 subcultures but then it increased 2 – 2.5-fold after each subculture (Table 1) Tomato plantlets grew much better in Phytacon vessels (5–6 explants in each vessel) than in test tubes As a result, the rate of micropropagation increased and subculture duration shortened to 3 weeks (Table 2). The addition of chlorocholine chloride (100 mg/dm-3) into the medium induced the retardation of stem elongation and allowed the subculture duration to be extended to 3 months which can be suitable for prolonged maintenance of micropropagated clones.
Most of the clones are being maintained now from August 1994. Transplants for greenhouse cultivation obtained one month after the transfer of plantlets to peat soil with fertilizers.
No off-type plants were observed during greenhouse cultivation.
Primordia of flower racemes appeared in 20–22% of plantlets The racemes were further developed when stem sections with the primordia were planted on fresh medium Flower buds were excised from the racemes and planted on basal medium with 4% sucrose, casein hydrolysate and gibberellic acid for flower development.
Treatment of the flowers with a drop of NAA 100 mg/dm -3 resulted in the growth of seedless fruitlets maturing 6–8 weeks after the treatment.
Thus, a full route from the initiation of flower raceme to fruit maturation was reproduced in vitro.